BlueDot

What can we learn from Measles in the US?

Chantal Castro — Wed, 04 Mar 2026 16:28:00 +0000

The largest US measles outbreak in over 25 years is unfolding, exposing a complex dynamic between risk, hesitancy and vaccination. Organizations everywhere can learn much from it.

Nestled between the bigger cities of Charlotte and Greenville, Spartanburg County is home to 400,000 South Carolinians. Here, BMW operates its largest production facility, employing 11,000 people amidst a multi-billion-dollar upgrade. Over the past 20 years, household incomes and educational outcomes have risen steadily. But Spartanburg has also mirrored a quieter national trend: declining vaccination rates that have reopened the door to diseases once considered eliminated.

In early October, the first measles cases appeared. In December, the county experienced a holiday surge, where church and school exposures drove the cases upward. By January, there was explosive growth: 185 cases reported on January 2nd. Over 500 cases by mid-January. By the end of the month, it exceeded 800 — making it the largest measles outbreak in the United States since the disease was declared eliminated in 2000. The outbreak spread across county lines and into neighbouring states. At the end of January, at least 15 states had reported measles cases, many of which were linked to the South Carolina cluster.

Spartanburg’s vaccination rate is below what is needed for herd immunity. But what made Spartanburg vulnerable is shared widely. Thirty-nine of America’s 50 states are below the herd immunity threshold. Countries around the globe are losing their measles vaccination status. But a growing body of recent research is clarifying not just where the risks are concentrated, but where the greatest opportunities for effective response lie.

The Coverage Picture

US measles vaccination has been quietly eroding for over a decade. Coverage sat near 95% through the 2010s. It spent the decade hovering just above the WHO recommendation for herd immunity. The pandemic accelerated the decline sharply, and it has not reversed. By 2024–25, national kindergarten MMR coverage had dropped to 92.5%. Non-medical exemptions have nearly tripled since 2011. CDC surveillance data underscores the link between vaccination and outbreaks: 93–95% of new measles cases in 2025 occurred in completely unvaccinated individuals. Roughly one quarter of cases are in children under 5 years old, some of whom are too young to receive a vaccine.

There is also a persistent gap between first and second doses. MMR Dose 1 rates run 5–10% higher than Dose 2, which is scheduled at age four to six (recommended before starting school). The drop-off is typically attributed to scheduling difficulty — parents who vaccinated once but did not return for the follow-up — rather than refusal. But the sharper danger is the growing number of children in the US with no protection at all. An analysis of over 320,000 electronic health records, published in JAMA Network Open in January 2026, found that between 2020 to 2024, the share of children reaching age two with zero MMR doses has climbed from 5.3% to 7.7%.

"It's not that bad"

One recurring theme in the literature on vaccine hesitancy is the belief that measles is a minor illness — a “forgotten disease” that does not justify the perceived risks of vaccination. The clinical data says otherwise. In 2025, about one in eight US measles patients required hospitalization — rising to nearly a quarter for children under five. Measles in infancy and childhood often leads to immune amnesia, or the depletion of immune memory to other pathogens, which can last up to 5 years. And infections can be fatal in about 1 in 1,000 cases in high-income settings. The seriousness of this disease in infants is one of the reasons why herd immunity is so important, in that it protects those among us who are the most vulnerable.

On a per-case basis, measles puts a huge burden on the operational resiliency of an organization. Patient absenteeism runs 10–14 days. Caregiver absenteeism — parents staying home with sick children — averages 9–15 lost workdays per case. These are exceptionally prolonged absences compared to most common diseases. A 2025 Johns Hopkins systematic review of US measles outbreaks found the average total cost per case was $43,203, nearly half driven by productivity loss. School and work absences during outbreaks run roughly ten times higher than actual case counts — a product of 21-day quarantine protocols for unvaccinated contacts.

On our radar (spotlight on Measles)

While much attention has been paid to the growing situation in the United States, our reporting shows there are several concerning outbreaks across the globe.

Measles in South and Central America

A sustained increase in measles cases has been reported in the Region of the Americas in 2025 compared to recent years; a trend that has continued into 2026. Several countries entered 2026 with active outbreaks: As of mid-Feb 2026, eight countries had reported a case within the previous 42 days, indicating ongoing outbreak activity (Costa Rica, Argentina, Guatemala, Chile, Peru, Uruguay, Honduras, El Salvador). Low vaccination coverage, paired with population mobility, may contribute to rapid outbreak amplification, as demonstrated in Guatemala following a mass gathering that was held between 10-14 December 2025 that has since resulted in sustained local transmission and travel-associated cases in nearby regions.

We recently conducted a deep dive Intelligence Report on the situation in South and Central America. Outbreak Insider readers may contact us to read the report.

Other Measles Outbreaks in Early 2026

In January and February of this year, we have reported on concerning outbreaks in multiple areas of the globe.

In the MENA region, Yemen and Israel both reported significant outbreaks. In Yemen, a sharp spike of cases comes paired with the concerning likelihood of significant underreporting. Israel experienced clusters of cases across the country, with most cases being reported in Jerusalem. Somalia and Sudan have also been experiencing large outbreaks. In Sub-Saharan Africa, the DRC and Angola reported continued significant activity of measles. In both instances, these events were carried over the prior year.

While Europe has not yet had an outbreak that rose to our notable event criteria, it is worth noting that 2025 saw notable outbreaks in France, Spain, Italy, the Netherlands and the United Kingdom. In early February, 3 European countries were among the 6 that lost measles elimination status, a foreboding sign for 2026. The BlueDot team continues to monitor activity on the continent carefully.

Lastly, Mexico is reporting its worst outbreak in over 20 years. Cases have been reported in every state in the country. The outbreak originated from a cluster in Texas, and Chihuahua, a state bordering Texas and New Mexico, is reporting the highest burden of cases in the country.

In the past 12 months alone, BlueDot has issued 106 alerts for notable measles outbreaks. When paired with our personalization engine and information on travel connectivity, clients are offered prioritized, timely updates on all disease threats relevant to their operations and communities.

The US Risk Map

National and state-level vaccination statistics create a misleading picture of measles vulnerability. At the state level, the gap is already stark: Idaho’s kindergarten coverage is below 79%; Connecticut’s is above 98%. But the real risk is concentrated in pockets that even state-level data obscure.

A January 2026 study in Nature Health surveyed 22,062 parents of children under five to generate county-level MMR coverage estimates across the United States. The results were sharply different from official figures. The median county-level coverage was just 71% — and ranged from as low as 36% to a high of 87%, well short of the 95% threshold. The gap partly reflects who the study captures: official data relies on school-entry records, which miss homeschooled and uninsured children — populations that participatory surveillance is designed to reach.

The study identified clusters of low coverage — hot spots — in West Texas, southern New Mexico, parts of Mississippi, and across the rural Southeast. Low-coverage areas clustered together geographically, creating contiguous zones of vulnerability. Where clustering was present, measles cases were more than twice as likely.

South Carolina’s county-level data broadly supports this picture. Not a single county in the state reached 80% coverage in the study’s estimates. Twenty-six of the state’s 46 counties were classified as low-coverage clusters — low-coverage counties surrounded by other low-coverage counties. The data was collected before the outbreak began.

But Spartanburg County — where the outbreak ignited — was not one of them. At just under 75%, it was among the state’s better-covered counties — and not flagged as a cluster. The outbreak started there anyway. Coverage 20 points below herd immunity is dangerous whether or not the county next door is worse. Clustering indicates areas of risk, but any community with insufficient vaccine coverage is susceptible to outbreaks.

Why Coverage is Falling

Vaccine coverage and vaccine hesitancy is a well-studied topic, but the COVID-19 pandemic has, in some cases, worsened sharp societal shifts on the topic. Recent research offers clues into what has, and hasn’t changed. It also offers some important guidance on ways to combat the trend of downward vaccine adoption.

Who refuses — and why

Active refusal — parents who deliberately opt out of vaccination — represents 2–3.6% of the population nationally. But this group clusters geographically, creating localized pockets where herd immunity collapses.

A July 2025 study in JAMA Network Open surveyed 174 pregnant individuals and 1,765 parents of children aged zero to five. Among parents with existing children, more than one in five intended to refuse all vaccines — a dramatic jump from under 2% among first-time expectant parents. The most common reasons: a preference for natural immunity, concerns about vaccine ingredients, and discomfort with multiple shots at a single visit.

The strongest predictor of refusal was a negative prior experience — a perceived side effect that the parent felt was not adequately explained by their paediatrician. Refusal was higher among parents who felt their concerns had been dismissed.

A window that closes

The same study revealed a striking pattern. Among first-time pregnant women, nearly half described themselves as uncertain about their child’s future vaccinations. Their concerns closely mirrored those of active refusers — long-term safety, multiple shots at one visit, contradictory information online — but their positions had not yet hardened.

But among parents who already had children, uncertainty dropped to 3.5% from nearly 50%. Parents move from undecided to decided, and the decision increasingly skews toward refusal. First-time parents are reachable — their concerns are specific and addressable. But the window is narrow, and once it closes, opinions become much stronger.

The clinical record supports this. The JAMA Network Open analysis of children’s health records found that those with regular healthcare access who missed their two-month or four-month routine appointments were significantly more likely to never receive the MMR at all. Early disengagement from the healthcare system — whether from hesitancy or logistics — compounds over time.

The practical gap

Not all under vaccination is ideological. A 2022 analysis of National Immunization Survey data found that parental hesitancy accounts for about 25% of undervaccination in children. The remaining 75% is driven largely by structural barriers: lack of insurance, transportation, inability to take time off work, and clinic logistics. Parents also overestimate their child’s vaccination status by about 10–15% — the missing shots are typically not the result of a deliberate decision, but of a schedule that fell behind. Children without a consistent primary care provider are 15% more likely to be behind on their MMR series, regardless of their parents’ beliefs about vaccines.

Who is trusted

Public support for school vaccination requirements has dropped from 82% in 2019 to 69% in late 2025. Trust in the CDC and pharmaceutical companies has eroded across the political spectrum. But the data also reveals where effective engagement is still possible — and who is best positioned to deliver it.

Personal healthcare providers remain the most trusted source of vaccine information — even among hesitant and refusing parents. On a five-point scale, parents rated trust in their personal provider at 3.8 — nearly double the CDC and more than double pharmaceutical companies. This gap appeared consistently across the data, including among parents who intend to refuse vaccination entirely.

Research supports what makes provider communication effective. A 2024 study in the Journal of Health Communication found that storytelling and personal anecdotes were significantly more persuasive than statistical posts or expert-driven data for vaccine-hesitant parents. Personal narratives outweigh institutional data for the undecided group. The format matters as much as the messenger.

But the clinicians need support. A December 2025 Leger study found that only 40% of frontline healthcare workers feel confident addressing vaccine hesitancy with patients. The pathway is clear: trusted providers, narrative communication, targeted engagement with first-time parents. Actively equipping clinical teams with timely, accurate, and compelling information is the single highest-leverage investment in vaccination uptake.

BlueDot enables in-depth support to clinicians.

BlueDot works closely with Public Health of all types, including those who are tasked with supporting clinical networks with accurate, digestible and timely updates on infectious disease risk.

Key Takeaways

Measles is more severe than the popular imagination suggests: Measles has a 13% hospitalization rate (and nearly 25% for those under five), illnesses that require weeks of absenteeism on average, and quarantine protocols that produce ten times more absences than actual infections. The perception that measles is a minor childhood illness persists — and it undermines urgency at every level.
Know the hot spots in your area — but know that outbreaks don’t only start there: County-level data reveals sharp geographic variation in coverage, with clustering that doubles the likelihood of outbreaks. But Spartanburg was among South Carolina’s higher-coverage counties and still became the epicentre of the largest US outbreak in over 25 years. Risk exists well beyond the identified hot spots.
First-time parents are the key engagement window: Nearly half of first-time expectant parents are uncertain about vaccination. After the first child, positions harden — and the share intending to refuse jumps from under 2% to over 22%. The window for effective engagement is narrow and early.
Clinicians are the most trusted messengers — and they need support: Provider trust scores nearly double the CDC’s, even among hesitant parents. Narrative communication outperforms data-driven messaging. But only 40% of frontline healthcare workers feel confident addressing vaccine hesitancy, citing misinformation fatigue. Supporting clinical networks with timely, accurate, and compelling information is the most direct path to reaching the populations that matter most.

BlueDot works with leading organizations in public health, life science, along with enterprise risk management and occupational health and safety teams across the private sector. We detect, triage and advise on infectious disease threats worldwide, empowering our clients to take effective action in the face of infectious disease. If you would like to learn more about our intelligence and services, please get in touch.

To get monthly data-driven expert analyses on infectious diseases, sign up here to receive every edition of Outbreak Insider.

The post What can we learn from Measles in the US? appeared first on BlueDot.

Beware the “Superflu” hype: How infectious disease surveillance goes beyond the headlines

Chantal Castro — Mon, 26 Jan 2026 16:17:57 +0000

When it comes to outbreaks, media reporting is a critical resource—but its trade-offs cannot be ignored

In 2025, country after country reported a significant rise in influenza infections, often a full month earlier than the typical start to the flu season. In the United States, Canada, Europe and Japan, cases grew rapidly, and severe infections and hospitalizations were beginning to strain healthcare systems. In December, the media dubbed it a “superflu,” a term that has since dominated headlines and fueled public concern of a catastrophic flu season.

For BlueDot’s infectious disease surveillance team, the “superflu” moniker isn’t supported by the data. The team tracks influenza-like illnesses globally, year-round, using a diversity of sources in complement to media reporting. The ability to track media reporting provides an undeniable advantage, as BlueDot’s team has access to rapid, local reporting at global scale. But the “superflu” is an illustration of the complexity that comes with media reporting. Media signals often travel faster, and more loudly, than the science to support them. This can create added challenge in assessing the true risk of a disease, not to mention an additional dynamic of public perception that can complicate response efforts.

BlueDot’s head of surveillance Dr. Mariana Torres Portillo sat down to discuss the “superflu” phenomenon, and how robust surveillance systems can separate signal from noise.

The term “superflu” seems to have made its way into just about every news report about this year’s flu season. For weeks the headlines claimed it was, but more recently some say it’s not. So, which is it?

I would say “no,” but it’s a hard question to answer, because there’s no real definition of a “superflu.” The available evidence shows that this season has been dominated by a variant of influenza A H3N2, a known strain that hasn’t been the dominant influenza strain in several years. There are mutations in this strain that made it particularly good at evading existing immunity.

What likely happened is that natural immunity against H3N2 had waned over time, and the early epidemic waves in several countries meant that regularly scheduled vaccine programs were lagging, leaving populations with more limited defense systems before infection struck. We saw large outbreaks in schools, as an example, but the overall peak activity has not surpassed last year in many locations. It raised alarm bells because of its mutations and rapid spread. With that came many questions about whether it was more severe than other strains, and to what degree available vaccines would be effective against it. That’s how the term “superflu” emerged in the media, but it’s not founded in the available data or research.

What does the term “superflu” actually mean? Is it a scientific term?

Nope! But I can understand why the term arose. We monitor ILIs year-round, so we’re more accustomed to the uncertainty that’s inherent to infectious disease surveillance. It’s our business not to jump to conclusions. But it’s common for reporting around flu season to use more alarmist language. Often, the headlines say we are experiencing the “worst season yet.” Because this season started so early in some places, comparisons to the same week last year made things appear substantially worse, and the media ran with that.

When would we know if we are experiencing a “super flu” or dealing with the “worst flu season”?

We don’t know the answer to this with certainty when we are in the thick of ILI season. Terminology like the “superflu” suggests clear, obvious evidence: we don’t often see that in the middle of the season, and absolutely didn’t this season.

When the data aren’t clear, we work to stay ahead of the curve. The key is to assess several data points and sources, including peak activity, the number of severe cases requiring medical care, and cumulative data as the season progresses. We look at CDC data, media reporting, wastewater data, and other sources throughout the season.

Because the timing of flu epidemics can shift year-to-year, it is very difficult to assess whether we are seeing the early stages of a severe season, or just an early start to a somewhat more normal season. Early starts can have major consequences, but many people will look at a year-to-year comparison and assume some kind of catastrophic future.

We saw big regional differences, too. We can’t assume that a trend in one place is the trend everywhere. Frankly, this season showed significant variability in timing, size and geography. Often, definitive answers only come after the season, so assessing risk in real-time requires hard work and a degree of humility.

We’re accustomed to the fact that the media’s incentives are different than ours. Our job is to assess risk: that means covering events that don’t get widespread coverage, maintaining our focus on an event after the coverage has waned, or managing situations where risk has been overstated. Especially when there is novelty or new threats, media coverage can significantly exceed the true threat to the public. It’s not that different from our COVID experience of constantly hearing about “supervariants.” The media can create real urgency over uncertain data. Over time, this can desensitize audiences or distort risk perception.

There’s a lot of noise about this year’s flu and ILI activity.
Let’s cut through it. 

Curious to learn more about what’s really happening with ILIs this season? Join BlueDot on January 29 for Tracking Infectious Threats: Key Outbreaks of 2025 and Risks of 2026, a webinar where our experts break down the current ILI season in the Northern Hemisphere, highlight key shifts from the past year, and share what they’re watching for in the months ahead. 

Save your spot here and stay ahead of the curve with evidence-based, actionable insights you can trust. Can’t make it the date? Register anyway to receive the recording.

When you see a novel threat being reported in the media, what questions are you asking to assess the true risk?

The complete list of questions would extend this interview by about two days! But here are three questions we ask every time.

First, “what’s missing from the facts we have?” Initial reports are sometimes missing critical pieces of information. In the summer of 2022, we observed an “unknown illness” event in Argentina that had some concerning elements, but the diagnostic information wasn’t sufficient to really sound the alarm. Throughout our reporting, we were clear with our clients: the risk profile is concerning, but it’s early. It turned out to be Legionella, which can be serious, but not the novel threat it appeared to be. Over the years we’ve learned to recognize which locations regularly report unknown illnesses that fit this profile — the cause is usually resource constraints — and to anticipate and identify likely false positives. We keep a close eye on them, but we exercise judgement before reporting on them.

Second, “how might this report be wrong?” We are often more skeptical of media reports than even our most discerning clients. Last summer, reports from Cambodia suggested human-to-human transmission of H5N1. If that were true, it would be a likely driver of global disruption. It’s something we are constantly on the lookout for. In this case, the reports of the transmission pathway were due to a translation error, not the event itself. We uncovered this very early, but watched the media circulate the error for weeks after we had informed our clients of the truth.

Third, “What would drive its spread?” What, if anything, would create a major disruption, whether for nearby communities, countries or the world at large? It’s actually a series of multifaceted questions that we run through. At the end of the day, we know there can be false signals, but we obviously have also seen these events turn into major disruptions.

Wasn’t it through media reports that BlueDot caught early signals of COVID-19?

That’s correct. Our digital early warning system detected signals of a pneumonia-like outbreak in Wuhan through a Chinese trade publication, which is a pretty obscure source to be honest.

I remember seeing it for the first time. I had only been at BlueDot a short time. The publication said that over the past few days people were presenting severe pneumonia of unknown origin—a relatively small number of cases. But we were not seeing information on what tests were being performed. As a clinician, I found this highly unusual, because you know you can test for Streptococcus or influenza and get results right away. When I connected that clue with the proximity to a wet market, I knew this was a major priority for our team to investigate.

So, we followed through with further research, because we still need our team of experts to identify the significance of the signals. But the media reporting is what allowed us to sound the alarm even before the World Health Organization and the US CDC did. 

The ILI season is a whirlwind — but it doesn’t have to be. Sign up here for BlueDot’s biweekly ILI reports to gain valuable insight into the latest flu trends and what the data mean to inform your prevention strategies.

With that in mind, have you seen any major changes in the way the media discusses infectious disease?

Before COVID-19, people weren’t really conscious that serious, truly global pandemics were even possible. It was very difficult for non-experts, whether in the media or the public at large, to imagine that this could affect nearly every person in the world.

Now, we’re almost in a state of hyperawareness. We are seeing many false positives and are in a position where our own clients are being asked to answer questions about events that never would have entered the public eye before 2020. And this is just in reference to real, credible medical reports. We are also seeing this hyperawareness drive misinformation and conspiracy theories.

This awareness isn’t necessarily misplaced. There are many drivers that are increasing the likelihood of another major pandemic. With that in mind, we would rather have too much information than too little. But, you need to have the skill and clarity to sort through the false alarms.

So the fact that the media, and the public, are now actively looking for the next global emergency, is a good thing in your view?

Absolutely. It puts pressure on us to do our job well. While it’s true we’re focused on “early warning,” we are also the antidote to the issue of “crying wolf.” I had a very validating call with a client just last week. A relatively small local health unit, basically a suburb of a larger city, was describing to us how they now can effectively track and deliver important information about events all over the world—without being buried in noise. It’s a level of visibility that would be impossible before. Honestly, it’s hearing things like that that reminds me why I love doing this so much.

3 Top Takeaways

This flu season was far more complex than the word “superflu” would imply. The dominant strain this season was the re-emergence of influenza A H3N2: a known influenza strain that hadn’t been dominant for some time. Meanwhile, multiple locations had early and rapid starts to otherwise normal seasons. Some areas are experiencing very severe seasons. Especially for regional or multinational organizations, the defining trait of the season was its variability and complexity.
Novel language like the superflu can complicate objective risk assessments. Attention-grabbing words can obscure the true facts, drum up unfounded public concern and can jeopardize trust for years to come. Managing risks when the facts are far more mixed than the dominant narrative is a challenge that is only getting more demanding in our current media environment.
For early reporting, context is key: False alarms are common in today’s media environment. The concern around the next major outbreak is well-founded: BlueDot’s surveillance team views false alarms as a good problem to have. But such an environment underscores the need to have sustained, expert analysis that uses every clue available to clearly assess risks.

On our radar

Mpox Clade Ib in Europe and the Americas: From Brazil to Germany and Spain, mpox Clade Ib has been detected outside of usual endemic zones, with a growing number of cases lacking clear travel links to endemic regions. Germany confirmed its first-ever case of locally acquired mpox Clade Ib on January 10. Two days later, Brazil confirmed its second case of mpox Clade I in a traveler from Portugal — where no cases have been reported. The emergence of Clade Ib in these non-endemic areas, a trend initially detected early last year, suggests a degree of community transmission and highlights the importance of enhanced surveillance and targeted vaccination programs.
Nipah in India and Bangladesh: As of January 18, 5 confirmed and suspected cases of Nipah virus have been reported in West Bengal, India. The state’s first confirmed outbreak since 2007, this zoonotic disease has been linked to healthcare-associated transmission. The affected area lies near the Bangladesh–India border, where recurrent Nipah virus spillover has been documented. These cases follow nearby Bangladesh’s 4 cases last year, all of which were fatal. Nipah virus often causes severe complications, such as encephalitis, and has a high fatality rate (40-75%), leading health authorities to increase surveillance and containment protocols. BlueDot is closely monitoring the situation for further transmission and cross-border spread.
Measles in the Americas: On January 12, Guatemala confirmed a measles outbreak in Santiago Atitlán following a mass gathering event last month, which appears to have triggered rapid transmission. Case counts have since risen sharply, with nearly 40 cases now reported, marking Guatemala’s first measles outbreak in almost 30 years after decades of elimination. Cross-border spread has been detected, including imported cases in El Salvador and Chile linked to air travel. Neighbouring countries are also reporting rapid escalation, notably Honduras, where cases increased from four imported infections to 42 in less than a week. These developments, alongside ongoing measles activity in Mexico and the United States, highlight the virus’s extreme transmissibility and the continued importance of vaccination and mass-gathering risk assessment.

To get monthly data-driven expert analyses on infectious diseases, sign up here to receive every edition of Outbreak Insider.

Lastly, don’t forget to sign up for our webinar. Join BlueDot on January 29 for Tracking Infectious Threats: Key Outbreaks of 2025 and Risks of 2026, a webinar where our experts break down the current ILI season in the Northern Hemisphere, highlight key shifts from the past year, and share what they’re watching for in the months ahead. 

Save your spot here. Can’t make it the date? Register anyway to receive the recording.

The post Beware the “Superflu” hype: How infectious disease surveillance goes beyond the headlines appeared first on BlueDot.

Tracking Infectious Threats: Key Outbreaks of 2025 and Risks for 2026

Chantal Castro — Wed, 07 Jan 2026 19:32:56 +0000

The global infectious disease landscape is shifting faster than ever. In 2025, outbreaks and influenza-like illnesses (ILI) spread unpredictably, testing public health systems and organizational preparedness. As we head into 2026, knowing which signals truly matter—and understanding their potential impact on your community or operations—has never been more critical.

In this webinar we explored how recent trends can inform proactive planning, and what emerging signals suggest for the year ahead.

Dr. Andrea Thomas, Head of Epidemiology, hosted Anindita Marwah, MPH, Senior Epidemiologist and Kathleen Williams, MSc, Senior Epidemiologist Analyst for an in-depth look at the top infectious disease threats of 2025, updates on the ILI season in the Northern Hemisphere, and early signals shaping 2026.

Key topics covered included:

The major events and trends that defined 2025’s infectious disease and ILI landscape
Early warning signals we’re monitoring for 2026 to anticipate potential risks
How data-driven intelligence can guide proactive, informed decisions

This webinar will equip you with actionable insights to stay ahead of fast-moving threats!

Fill out the form to access the recording!

Interested in learning more about our technology? Get in touch with us and we’ll be happy to connect you with one of our experts!

The post Tracking Infectious Threats: Key Outbreaks of 2025 and Risks for 2026 appeared first on BlueDot.

The most notable infectious disease events of 2025

Chantal Castro — Thu, 18 Dec 2025 19:24:32 +0000

Three battles we fought — and another we won — against emerging threats and resurgent foes over the past year

From unexpected outbreaks that challenged global health systems to groundbreaking advancements in disease surveillance and prevention, this past year has been a whirlwind of activity in the world of infectious diseases and disease prevention.

Widespread cases of chikungunya, avian influenza, and cholera emerged in the midst of a warming climate and ongoing regional conflicts. Vaccine-preventable diseases such as measles and pertussis resurfaced — the long tail of the fallout from both COVID-19-related disruptions to vaccine programs and vaccine hesitancy. At the same time, enhanced public health measures saw severe diseases like Ebola rapidly contained before mass devastation occurred.

“Not everything we saw came as a surprise,” says Andrea Thomas, BlueDot’s head of epidemiology. “Reflecting on this year reminds us that the battle against infectious diseases is never truly over.”

This edition of Outbreak Insider covers strides made, setbacks faced, and barriers overcome in 2025, and what to look out for in 2026.

Evading an Ebola emergency

On September 3, a reported unknown hemorrhagic illness resulted in the deaths of eight people in the Democratic Republic of the Congo (DRC). The next day, the outbreak was confirmed as Ebola, a rare but often fatal illness first detected in 1976. It marked the DRC’s 16th recorded outbreak since Ebola’s discovery, but genomic sequencing identified that the strain more closely resembled the 1976 strain, indicating a new zoonotic spillover event between animals and humans.

The risk of uncontained community spread was high. But by the end of September, thanks to immediate community outreach, rapid deployment of medical teams and countermeasures including vaccines and personal protective equipment (PPE), cases had waned. On December 1, the outbreak was declared over following 42 consecutive days without a new case.

“Controlling an Ebola outbreak in three months is an inspiring example of the power of collaborative, multi-sectoral response,” says Dr. Mariana Torres Portillo, BlueDot’s head of surveillance. In total, 64 cases and 45 deaths were reported. While these outcomes are tragic, the decisive actions taken were crucial in preventing the disease from spreading further, saving countless lives.

Wins such as this do not always occur because of longstanding inequities in access to available countermeasures. Countries such as the DRC often rely on global support to bolster country-level systems and expertise, especially in resource-limited locations. But when these challenges are overcome, they are beacons for what public health agencies and workers can accomplish.

Setbacks on the frontlines

Where gaps exist and ability to respond is impaired, infectious diseases can thrive. This year, cholera, an acute diarrheal illness, was the old adversary that resurged in Africa and the Middle East. Severely damaged infrastructure and poorly resourced health systems in humanitarian crisis zones created an inaccessibility to safe water, sanitation, and hygiene, as well as delayed access to treatment, producing ideal conditions for the bacteria to thrive.

A total of 565,404 cases and 7,074 deaths have been reported across 32 countries this year, largely in Africa, but also across parts of the Middle East and South Asia. Africa is in the midst of its worst outbreak in 25 years as cases and deaths exceed 311,000 and 7,000, respectively. The hardest hit nations are South Sudan (78,034 cases), Sudan (72,000), the DRC (63,521), and Angola (35,163), which together account for approximately 85% of deaths, according to the latest Africa Centres for Disease Control and Prevention (CDC) weekly report.

Cholera and AWD cases per 100,000, Jan. 1-Oct. 26, 2025

Source: World Health Organization, Multi-country Outbreak of Cholera External Situation Report n. 32, published November 26, 2025.

Afghanistan and Yemen combined have seen more than 233,000 cases of cholera and acute watery diarrhea (AWD) in 2025. For nations in all these regions, conflict and natural disasters have caused destruction, mass displacement, and overcrowding. Combined with limited oral cholera vaccine (OCV) supply and challenges to timely delivery, 1 billion people are at risk of infection. Efforts to combat this long-time foe, such as the Global Roadmap to End Cholera by 2030, offer guidance and hope in achieving victory.

Another old foe of public health also made a resurgence in 2025 — despite having the tools necessary to fight it. Measles, the highly contagious, vaccine-preventable respiratory virus resurged in regions that typically do not see uncontrolled spread. Approximately 492,000 cases have been reported so far this year, compared to 475,000 cases last year. Since 2021, the number of countries experiencing large measles outbreaks has tripled. And while measles deaths have fallen since 2000, an estimated 95,000 deaths in 2024, mostly among children under 5, underscore a painful truth: children are still dying from a disease we can prevent.

The spread of measles is driven by immunization gaps, which have been exacerbated by pandemic-related disruptions and increased vaccine hesitancy. Access to and distribution of the highly effective vaccine remains an issue for some areas. For others, a decline in immunization — often the result of misinformation or lack of trust — was the culprit. In the Americas, where measles vaccines are widely available, first- and second-dose vaccination rates were 88% and 77%, respectively, dropping below the recommended threshold of 95%. Communities with lower immunization proved particularly vulnerable to importation and circulation.

Measles Incidence in 2025 and Vaccination Coverage with a Second Dose of Measles-Containing Vaccine for 2024, January 1 to December 15, 2025

Data from BlueDot Human Disease Case and Death Counts API and WHO Immunization Data Portal, accessed December 15, 2025. Source: BlueDot 2025 Measles Report

Last month, Canada lost its nearly 30-year measles-free status as cases surpassed 5,200. The US and Mexico are at risk of losing their elimination statuses early in the new year. “Barriers to widespread vaccination, whether it be for cholera in conflict zones or measles in vaccine-hesitant communities, have far-reaching implications for diseases we’ve been waging war with for a very long time,” says Torres Portillo.

If there is a silver lining to measles’ resurgence, it’s to be found in Africa. The continent made substantial headway in measles immunization: first-dose rates hit 71% in 2024, up 50% from 2000; second-dose rates hit 55% in 2024, a 1000% increase from just 5% in 2000. In the same timeframe, there has been a 40% decrease in cases and 50% reduction in deaths.

This year also saw a less anticipated but dominant infectious disease opponent: arboviruses. Mosquito-borne diseases like chikungunya soared, evidenced by the 44 alerts sent out by BlueDot since January. This once regional disease is now a global one, with more than 445,000 chikungunya cases and 155 deaths reported across 40 countries as of the end of September. Cases not only spiked in endemic countries including Sri Lanka and Brazil, but the disease also reemerged on the islands of Réunion, Mayotte, and Mauritius and began circulating locally for the first time in China, France, and the US.

Global chikungunya outbreak status and total reported cases, Jan. 1, 2024-Dec. 10, 2025

Note: Grey = no data/no status available. “Reemergence” indicates cases that are not currently endemic but are capable of periodic reemergence due to local vector presence and population susceptibility.

Data Source: BlueDot Human Cases and Death API and PAHO Chikungunya analysis by country, accessed 10-Dec-2025. Note: Population size of countries is from 2021–2022.

The widespread surge in mosquito-borne diseases is influenced by climate change, which has been shown to aggravate nearly 60% of infectious diseases. For example, warmer weather and altered rainfall in Europe are creating the perfect environment for chikungunya-carrying mosquitoes to flourish. The Aedes albopictus mosquito is now established in 16 European countries, meaning outbreaks of mosquito-borne diseases are becoming the norm. By the end of August, the continent had recorded 27 chikungunya outbreaks. It also recorded the highest number of West Nile virus cases in three years. The expansion of suitable habitats and longer seasons for infectious disease-carrying vectors is likely to lead to more outbreaks around the globe.

The emergence of chikungunya in new areas is not just an artefact of climate change; it is linked to increased human movement and connectivity, as travelers can introduce diseases and vectors can hitch rides to new land. Travel-associated cases, along with vector presence and environmental suitability, can ultimately lead to local transmission. This series of events is what led to this year’s outbreak in Guangdong, China, which resulted in over 16,000 cases. Importation also catalyzed the outbreaks in France, Italy, and the US.

3 Top Takeaways from 2025

Ebola is proof that preparedness pays off. Detection of the highly fatal and difficult-to-contain hemorrhagic disease in the DRC in early September sent warnings of a potentially devastating outbreak. But rapid, multi-sectoral action ushered in the end of the outbreak on December 1.
Infectious disease battles engaged combatants old and new. Cholera, measles, and chikungunya dominated, exposing gaps in basic sanitation, immunization, and surveillance. Conflict, climate change, human movement, and reduced immunizations were catalysts for disease transmission.
New year, new battleground. Environmental and socio-political pressures mean diseases like avian influenza, polio, and tick-borne diseases are threats to watch in 2026. But with advancements in artificial intelligence and machine learning, timelier surveillance provides hope for improved time to action.

Global outbreaks exposed inadequate surveillance and reporting of mosquito-borne diseases. Outbreaks are often reported retrospectively, resulting in significant delays in outbreak communications and initiation of important prevention measures. In a recent BlueDot analysis, there was a median 79-day lag between outbreak detection and official outbreak declarations or advisories in 2025 — vastly longer than BlueDot’s median 3-day lag. And only 56% of chikungunya outbreaks were declared by major health agencies, while nearly 30% went completely undeclared.

These delays in official reporting, combined with the propensity for travel-related importation, have led many sub-national public health agencies to follow their own lead, seeking out alternate intelligence sources such as BlueDot and taking steps to mitigate travel-related spread before official announcements are made.

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Forecasting infectious diseases in 2026

In the year ahead, BlueDot will be closely monitoring several infectious diseases — including some that made headlines and worried experts, and others that flew beneath the radar. Among the questions looming for 2025:

Will avian influenza continue to spread widely in many species, increasing the likelihood that a human-adapted strain could emerge?
Can catch-up initiatives restore immunization rates for measles and other vaccine-preventable illnesses like polio and pertussis?
How will climate change and other factors impact the burden of vector-borne diseases, whether spread by ticks, mosquitoes, or other insects?

As artificial intelligence and machine learning rapidly advance, so too will disease detection, diagnosis, and risk assessments. Knowledge is power and knowing when and where outbreaks are circulating is going to be key in navigating the challenge of tracking infectious diseases in an increasingly fragmented but highly connected world.

Stay ahead of what’s next

Infectious disease risks will continue to evolve in 2026, making timely and trusted intelligence critical for preparedness and response. BlueDot delivers near real-time disease data and expert-reviewed insights in an easy-to-use platform to help you understand where outbreaks are emerging, how risks are changing, and what to watch in the year ahead.

Learn how BlueDot supports early detection and informed decision-making.

Barriers to infectious diseases may not be disappearing anytime soon, but the tools to quickly identify and initiate prevention measures provide hope in reducing infectious disease burden in 2026.

In our interconnected and rapidly changing world, the threats posed by global infectious diseases are only increasing,” says BlueDot founder and CEO Kamran Khan. “But the technologies and solutions needed to quickly identify, assess, and respond to them are also advancing quickly. Leveraging these innovations is mission critical to strengthening organizational readiness and resilience in 2026 and beyond.”

On our radar

Novel mammarenavirus-like infection in Chad: On November 13, a new mammarenavirus was reported in a 37-year-old male with recent travel to Chad. Lab testing confirmed the pathogen was not Lassa virus, and the mode of transmission is unknown. Symptoms are severe, yet distinct, and the emergence of this new pathogen in an under-surveilled region is fueling investigation to mitigate broad exposure and identify potential viral hosts.
Marburg in Ethiopia: As of November 26, 13 cases and 8 deaths from Marburg have been reported in Ethiopia. The nation’s first historical outbreak of the disease, which was confirmed on November 14 in Jinka, has now spread to Hawassa — over 500km away. The source is not yet known, raising concerns about the risk of further spread within and across borders. Public health measures are rapidly gaining strength to track and limit infection, including a clinical trial with 640 doses of an investigational Marburg vaccine developed by the Sabin Vaccine Institute.
H5N2 in Mexico: A case of avian influenza(H5) reported on October 2 in Mexico City was confirmed a novel highly pathogenic reassortant strain of H5N2. A combination of clade 2.3.4.4b A(H5N1) and low pathogenic avian influenza (LPAI) A(H5N2), the strain shows mutations that may have resulted from mammalian adaptation during the human infection. This case marks the third human infection of influenza A(H5) in Mexico, amounting to 75 human cases reported across the Americas since 2022.

As Outbreak Insider winds down for the holiday season, BlueDot’s work will not. To keep up-to-date on outbreaks and expert insights, sign up here. We’ll see you in the new year for the latest in infectious disease news. Wishing you a healthy and happy holiday!

The post The most notable infectious disease events of 2025 appeared first on BlueDot.

How data blackouts and blind spots put organizations at risk

Chantal Castro — Thu, 20 Nov 2025 16:30:20 +0000

The U.S. government shutdown demonstrates how infectious disease data sources can dry up — and how third-party surveillance sees in the dark

The recent US government shutdown, lasting 43 days and furloughing around 670,000 federal employees, disrupted a multitude of programs and services. Not least among these were health research, disease surveillance, and expert public health guidance, all of which were halted just as seasonal respiratory illnesses returned.

As federal operations resume, state and local health departments — who are accustomed to depending upon federal data and guidance for their own planning and decision-making — are trying to fill the gaps. With government funding only secured through January, another data blackout is possible.

Shutdowns are just one example of how gaps in official surveillance data can emerge, with potentially damaging consequences for those who rely upon it. In conflict zones, which are afflicted by mass displacement and health infrastructure damage, tracking and testing for infectious diseases is especially difficult. And returning travelers can often point to outbreaks in places where local authorities have yet to fully ascertain them. Infectious diseases can capitalize on all these situations, spreading quickly and putting response efforts at a major disadvantage.

“Infectious disease surveillance is a complex web of official and unofficial sources that need to be analyzed and contextualized,” says Andrea Thomas, BlueDot’s Head of Epidemiology. “Data gaps pose immeasurable risks for human lives and healthcare systems around the world, emphasizing the importance of reliable and timely reporting.”

With the increasing frequency and scale of emerging infectious diseases, prompt, accurate, and multi-source monitoring systems are an ever-growing public health and enterprise need. This edition of Outbreak Insider investigates how these situations impact surveillance data, and how BlueDot’s techniques are used to fill in the gaps.

A synopsis of disease surveillance history and challenges

Disease surveillance is the bedrock of public health. Its origins date back to the 1300s in the Venetian Republic, when a system to detect and isolate ships with infected passengers was established. Over the following centuries, surveillance morphed from detecting disease to complex systems of data collection, analysis, interpretation, and dissemination to guide action. Today surveillance is vital for risk factor monitoring, epidemic detection, disease burden estimation and resource allocation, and informing vaccine and medication research and development.

But surveillance is also continuously beset by limited monitoring capabilities and resources, fragmented systems and coordination, non-standardized data collection and sharing, and political and economic pressures. When blind spots occur, morbidity and mortality increase, interventions are rendered less effective, and substantial economic damage can ensue.

When the dashboard goes dark

On October 1, the US federal government shutdown caused non-essential functions to cease. Caught up in the mix was the U.S. Centers for Disease Control and Infection (CDC), the country’s nationwide beacon of infectious disease intel. As dashboards dimmed and analysis abated, North America was entering its influenza-like illness (ILI) season. In the absence of updated disease trends, weekly reports, and expert analysis, state and municipal governments were left with a limited, patchwork perspective on nationwide disease activity and external threats.

What resulted was “DIY surveillance.” States are mandated to conduct infectious disease surveillance, such as wastewater monitoring, but capacity is variable. And their lines of communication with the CDC, which provided a nationwide perspective that kept them abreast of developments in surrounding regions, are not as robust as they have been in the past. With the data blackout, early outbreak warnings for influenza, COVID-19, and respiratory syncytial virus (RSV) were limited, leaving local health departments more susceptible to delayed responses.

Even with the shutdown now over, CDC job cuts and unstable funding create ongoing risks for data availability. The flu alone resulted in 47 million illnesses, 610,000 hospitalizations, 27,000 deaths across the US during last year’s season (October 2024 to May 2025), demonstrating the immense cost to human lives and the healthcare system.

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When official reporting slows or stops, BlueDot’s intelligence platform continues to track and verify emerging threats around the world. Stay informed with continuous, expert-reviewed updates tailored to your organization’s needs. Contact BlueDot to learn more.

War obscures warning signs

In a very different manner, ongoing violence in Sudan has also disrupted surveillance systems, contributing to a massive cholera outbreak. More than 50,000 cases and 1,350 deaths have been confirmed since the start of the year as millions of people were forced into camps that were overcrowded, unsanitary, and lacked clean water. Underreporting and delays in infection detection meant the outbreak rapidly grew out of control. And cholera was just one of several concurrent outbreaks, along with measles and malaria, that were reported in Sudan.

Instability due to conflicts, such as the one in Sudan, is another common barrier to disease surveillance. Mass population displacements and damage to health infrastructure, strain tracking, testing, and response systems. Before long, the absence of proper surveillance lets pathogens silently circulate among vulnerable populations.

Beyond missing early indicators of outbreaks, limited surveillance creates gaps in data that are used to confirm disease strains and inform preventive measures like vaccination and vector control. In the Gaza Strip, strained healthcare and lab systems led to insufficient information about an unknown respiratory illness, raising questions about the possibility of a new influenza strain. Last year, the detection of acute flaccid paralysis (AFP) amid Gaza’s limited surveillance capabilities fueled concerns about polio transmission.

Over 100 armed conflicts are ongoing worldwide. The inability to track real-time trends and the risk associated with unknown strains or symptomatology without proper lab capacity pose acute and downstream impacts. Conflict-affected regions, humanitarian agencies, and global public health bodies grapple with uncoordinated data collection, analysis, and response — before widespread outbreaks put them in damage control mode.

3 Top Takeaways

Data blackouts come in many shapes and sizes. Political instability, lack of resources and infrastructure, and inhibited data collection and sharing, such as during government shutdowns and conflicts, are factors underlying infectious disease surveillance gaps.
The implications of impaired disease monitoring can be immense. When outbreak detection is delayed or missed, diseases can spread quickly as containment measures lag, leading to lost productivity, lost lives, and strained health systems.
Diversified data sources provide effective surveillance. Tracking infectious diseases is an increasingly complex challenge in a more globalized world. Integrating more inputs into a surveillance framework allows for a timelier and more accurate picture of disease dynamics.

Blurred Borders

Earlier this summer, Taiwan, Macau, and the US issued health alerts for chikungunya in Guangdong, China as cases linked to travel emerged. While China had reported an outbreak, it was the travel-related cases that helped establish just how extensive it was. Similarly, in September, a Level 2 health alert for chikungunya in Cuba was issued by the US after returning travelers were diagnosed. Media reports pointed to widespread symptoms among the island nations’ residents, yet official case counts were unavailable.

These outbreaks demonstrate how travel-related cases can unveil surveillance gaps. Variability in local surveillance, underreporting from travelers and countries, and unstandardized and uncoordinated monitoring and reporting processes mean pathogens can reach new countries before outbreaks are even noticed. In some instances, such as Guangdong, international health alerts for imported cases can be a sign of the magnitude of an outbreak — or even a signal that an undiscovered outbreak is occurring.

Whether due to political and economic concerns or suboptimal monitoring, traditional surveillance methods are often insufficient in providing real-time and reliable travel data before diseases get transmitted.

Closing the surveillance gap

From BlueDot’s perspective, given the frequency and unpredictability of all these data delays and interruptions, any organization that relies on infectious disease surveillance cannot rely on official sources alone. BlueDot combines AI with human intelligence to scan, filter and analyze official and unofficial sources across languages around the globe, allowing us to identify and report on important events for over 190 diseases.

Indicator-based surveillance, such as case counts, hospitalizations, and deaths, and event-based surveillance, such as media reports and digital platforms (like internet search trends on symptoms), offer enormous pools of data from diverse sources. Unusual signals can prompt early-warning signs of outbreaks of both well-understood and emerging diseases. They can also provide valuable information to predict risk for nearby regions and travelers.

“Our methodology detected a cluster of ‘unusual pneumonia’ cases in Wuhan, China on December 31, 2019 — a week before the US CDC and the WHO issued statements,” says Thomas. “We sent out an alert as soon as we knew and notified clients about highly connected areas at risk.”

BlueDot’s Global Disease Surveillance Engine

Triangulating near real-time data from multiple sources overcomes inconsistent official data to support faster detection and response, which is critical in fast-moving outbreaks with limited formal reporting. Incorporating expert analysis is essential to see the forest for the trees. Validation of signals, putting them into context, and determining actionable insights help separate notable events from noise.

Advancements in technology have transformed the landscape of disease surveillance, overcoming long-standing challenges such as delayed reporting, fragmented systems, and barriers to data sharing. By harnessing the capabilities of BlueDot, organizations can enhance their ability to detect, analyze, and respond to outbreaks swiftly and effectively. Staying ahead of emerging threats is more achievable than ever — empowering public health professionals and decision-makers to protect communities with timely, reliable information.

On our radar

Poliomyelitis in Germany: On November 12, Germany’s national public health authority detected wild poliovirus type 1 (WPV1) — the rare, naturally occurring polio endemic only in Afghanistan and Pakistan — in a wastewater sample in Hamburg. Marking the country’s first environmental detection of WPV1 since 2021, the sample appears to be linked to a strain circulating in Afghanistan. Challenges in global polio eradication pose risks for importation around the globe.
Pertussis in Argentina and the US: Sharp rises in pertussis (or whooping cough), a vaccine-preventable disease, have been reported in Argentina and the US. The former saw a health alert issued in the Buenos Aires province after 5 infant fatalities, with cases exceeding 3,700 nationally. Similarly, a health alert was issued in Texas as cases surpassed 3,500 across the state. Infants, who are too young to be vaccinated, are at increased risk, highlighting the importance of up-to-date immunization status — especially among those in close contact.
Marburg in Ethiopia: The East African country is facing its first-ever outbreak of Marburg virus, which can cause severe hemorrhagic fever, in the country’s southern region. A total of 9 cases and 3 deaths have been confirmed to date, and 17 suspected cases have been identified in the Jinka city region. The virus is the same strain that has been reported in previous outbreaks in East Africa. There is no vaccine for Marburg, whose average case fatality rate is 50%.

Leveraging technology and subject matter expertise, BlueDot tracks infectious disease outbreaks around the globe as they are happening. To keep updated, sign up here to receive every edition of BlueDot Outbreak Insider.

The post How data blackouts and blind spots put organizations at risk appeared first on BlueDot.

Local Matches, Global Risks: Infectious Disease Surveillance, Connectivity and the 2026 World Cup

Chantal Castro — Mon, 03 Nov 2025 21:10:06 +0000

We have entered a new era of global mobility — one where mass gatherings and interconnected travel networks can rapidly amplify infectious disease risks. As the 2026 World Cup approaches, how can local public health teams prepare for the challenges that large-scale international events bring?

In this webinar, we explored the intersection of disease surveillance, global connectivity, and event preparedness, highlighting what health authorities need to know to anticipate and mitigate emerging threats.

Dr. Andrea Thomas, Head of Epidemiology, hosted Dr. Mariana Torres, Head of Global Surveillance and Josephine De Leon, MMASc, Manager of Applied Epidemiology, for an in-depth discussion on how data-driven intelligence can support readiness at the local level before, during, and after major mass gathering events.

Key topics covered included:

The “local-global loop”: how local outbreaks can escalate through international connectivity.
Lessons from previous global events and their implications for local surveillance systems.
Key trends our team is keeping an eye on ahead of the world’s largest sporting event.
Building event-based surveillance capacity at local levels to strengthen early warning, situational awareness, and response coordination.

Equip yourself with the insights needed to safeguard your community during high-impact global events.

Fill out the form to access the recording!

Interested in learning more about our technology? Get in touch with us and we’ll be happy to connect you with one of our experts!

The post Local Matches, Global Risks: Infectious Disease Surveillance, Connectivity and the 2026 World Cup appeared first on BlueDot.

The measles stress test: What 2025 taught us about global readiness

Chantal Castro — Thu, 23 Oct 2025 17:31:21 +0000

North America teeters on the edge of losing measles-free status, proving that disease elimination is not a finish line but a maintenance task

Next Monday, October 27, Canada will lose its measles elimination status, a designation it has held for almost 30 years, due to a sustained series of measles outbreaks in the past year. For similar reasons, both the United States and Mexico are also at risk of losing their measles-free status in the months ahead.

North America’s outbreaks are part of a measles resurgence that has erupted around the globe. More than 425,000 cases and 1,800 deaths have been reported to date in 2025, with an upward trend on track to surpass last year’s 475,000 total cases. In the Americas, measles cases are 25-fold higher than the same period last year, as of October 21.

“This wouldn’t be the first time a country has lost, or nearly lost, its measles-free status,” said Dr. Mariana Torres Portillo, BlueDot’s head of surveillance. At the same time, several countries have managed to regain control after significant outbreaks, and some have successfully restored their measles-free status. “Hope is not lost. What we want to avoid now is seeing measles become endemic again in the Americas, and the key is to increase vaccine coverage.”

This edition of Outbreak Insider takes a closer look at North America’s continued disease transmission, how other countries have regained control of outbreaks, and how BlueDot’s connectivity analyses offer key insights to mitigate risk.

From elimination to escalation: North America’s measles revival

Measles is a human-only viral infection that is transmitted by respiratory droplets. It is considered one of the world’s most contagious infectious diseases: one contagious person can infect 12-18 others. Approximately 40% of those with measles are hospitalized, and for some the disease can be fatal, notably for children who are as yet unvaccinated. Before the vaccine was available, epidemics were frequent, and 2.6 million lives were lost each year.

In Canada, measles was considered eliminated in 1998 following mass immunization. From 1998 to 2024 Canada averaged a mere 91 measles cases per year, with any outbreaks swiftly brought under control. But in October 2024, a single imported case from a returning traveler set off a chain reaction: the country has since recorded more than 5,000 cases and two deaths, more than in the previous 27 years combined, making Canada among the top countries reporting measles worldwide. In the United States, a total of 44 outbreaks and 1,596 cases have been reported to date in 2025, significantly fewer than Canada, but still a five-fold increase over the 285 cases the U.S. reported last year.

While each country’s original outbreaks (in Texas for the U.S., in New Brunswick and Ontario for Canada) has been declared over, others states and provinces are still working to either stabilize previous outbreaks or manage recent flare-ups.

Outbreaks are largely due to declining vaccine coverage — both countries’ vaccination rates have fallen below the 95% threshold needed to prevent outbreaks — and fueled by local transmission. Approximately 95% of Canada’s cases are among people who are unvaccinated, under-vaccinated, or with unknown vaccination status. The country’s first- and second-dose vaccination rates were 92% and 79%, respectively, in 2024 — substantially below the 95% threshold needed to prevent outbreaks.

Where coverage falters, measles flares

On a global scale, incidence of measles largely coincides with low vaccination coverage. Countries with high vaccination coverage, such as China, Norway, Sri Lanka, and Türkiye, have low incidence of measles. Likewise, countries with low vaccine coverage, including Cambodia, Mexico, Nigeria, and Romania, have high incidence.

Measles Incidence in 2025 and Vaccination Coverage with a Second Dose of Measles-Containing Vaccine for 2024, January 1 to October 21, 2025

Source: Data from BlueDot Human Disease Case and Death Counts API and WHO Immunization Data Portal, accessed Oct. 21, 2025.

There are also countries with low vaccination coverage (46-75%) and low incidence of disease, such as Brazil and Greece, as well as countries that have not reported any measles cases so far this year, including the Bahamas and Fiji — all of which are at risk of a measles resurgence given the disease’s increased global activity. Yet some countries, like Morocco, Mongolia, and Vietnam, have — like Canada — reported many new cases despite relatively high vaccination coverage. These cases exemplify the challenge of a disease as contagious as measles, which can spread quickly in any pockets of the population with suboptimal immunity.

Despite the challenge of controlling measles, there have been success stories. Since late 2023, Morocco has been battling an intense measles outbreak that has infected more than 25,000 people. In response, public health authorities initiated a mass vaccination campaign in March 2024 to fill immunization gaps. By April this year, focusing on the country’s 10.8 million people under age 18, Morocco had brought the national immunization rate above 98%. The benefits of this public health feat were immediate, with the country reporting an 80% reduction in measles incidence by May 2025.

Other countries have regained measles elimination status owing to enormous efforts to strengthen surveillance and preventive measures. Last November, Brazil was re-verified as measles-free after losing this status in early 2019 when an outbreak infected 21,700 people. Further, some countries have achieved or maintained measles-free status. Earlier this year, the WHO announced that all 21 Pacific Island countries had eliminated both measles and rubella. In 2016, Hong Kong was declared measles-free and has remained so amid a decade of concurrent outbreaks that threatened immunization programs. The key factor in the country’s success has been its consistently high two-dose coverage.

“There are no two ways about it, high immunization rates are the gold standard to prevent measles outbreaks,” says Dr. Torres Portillo. Since it was introduced, the measles vaccine has prevented tens of millions of deaths. It has been proven safe and effective, warding off almost 100% of illnesses and offering lifelong immunity.

3 Top Takeaways

Canada is on the cusp of forfeiting its measles-free status. Following a year of continuous transmission, Canada is close to losing a designation it’s held since 1998. The country has reported more than 5,000 cases and two deaths in 2025 to date.
Increased immunization brings outbreaks under control. Nearly 425,000 measles cases and 1,800 deaths have been reported around the globe so far this year. To contain disease resurgence, closing the immunization gap is crucial — and possible with a nearly 100% effective vaccine.
Endeavouring to achieve measles elimination. Low vaccination rates in communities around the world raise the risk for local, national, and international disease spread. Effective surveillance helps identify where outbreaks are occurring to initiate rapid response, minimize disease impact, and move the needle toward measles eradication.

Calculating connectivity

In the effort to eliminate measles, strong surveillance is the second-most important factor. With it, outbreaks can be quickly detected and contained. And with such high global connectivity, the risk of imported cases is significant — and heightened by the sustained outbreaks in the Americas, which have high connectivity with many other parts of the world. Depending on the timeliness and effectiveness of the response, introducing measles into a population of unimmunized people could have devastating effects.

For instance, Brazil’s population exceeds 210 million, and the country welcomed nearly 5 million visitors between January and May this year alone. Yet Brazil’s second-dose vaccine coverage in 2024 was only 68%, creating a substantial risk for outbreaks and the loss of their newly acquired measles-free status. Though much smaller in population (approximately 400,000), the Bahamas — a travel hotspot — saw a record-breaking 11 million visitors last year and only had 60% second-dose coverage.

Quantifying importation risk would help countries like Brazil and the Bahamas take the steps necessary to minimize outbreaks. By combining event-based and indicator-based surveillance with travel connectivity, BlueDot can map air and ground travel, allowing for prioritization and triage of locations most at risk of importation. This method accurately predicted measles transmission from the United States to the U.S.-Mexico border.

What does your region’s risk map look like?

BlueDot’s analysis of air and ground connectivity shows the travel linkages for any region, demonstrating where and when travelers arrive from different parts of the world — and the infectious diseases they’re most likely to bring with them. Contact us to learn more.

“One travel-related case in Canada opened the flood gates to a cascade of outbreaks that public health practitioners are still trying to control,” says Dr. Torres Portillo. Peak travel season is coming up in the United States, with thanksgiving get-togethers sending millions of travelers onto the road and into the skies for the holidays. Bookings in the US are already up 2% compared to last year, when an estimated 80 million travelers broke the nation’s record for air travel. Knowing where outbreaks are happening and how connected to them travelers are can protect at-risk populations — and help eliminate measles around the world.

On our radar

Heartland Virus in the USA: Heartland virus, an underreported but emerging tick-borne disease, was reported on October 15 in Missouri — the state’s first case this year. The disease is primarily transmitted by the Lone Star tick, which hitches rides on wild mammals across the southeastern and midwestern US. Heartland virus causes non-specific flu-like symptoms but can lead to hospitalization in some cases. Like most tick-borne diseases, Heartland virus likely goes undetected and undocumented in cases that are not severe, impairing an understanding of its severity and true activity.
Lyme disease in Slovakia: Another more well-known tick-borne disease has shown a substantial increase in the central European country. As of September 17, 3,127 cases of Lyme disease have been reported so far this year. Nearly three times higher than previous years’ averages, climate-related changes and limited prevention options are providing the ideal environment for disease transmission, with broader regional risk.
Chikungunya in New York: On October 14, 2025, New York State confirmed its first locally acquired case of chikungunya, a mosquito-borne virus, in a woman from Long Island with no travel history outside the state. This marks a significant milestone because it suggests that local mosquitoes—particularly Aedes albopictus, a species now established in parts of New York—may be capable of transmitting the virus for the first time in this northerly location. While health officials classify the risk as low and believe this to be an isolated case, it highlights how climate change, urbanization, and global travel are creating conditions for tropical diseases to appear in new regions.

Estimating risk of infectious disease transmission using BlueDot’s novel technique that integrates surveillance data and location connectivity by air and ground travel provides public health practitioners and healthcare professionals with the information necessary to prioritize their efforts to minimize disease impact.

To receive outbreak intelligence and expert insights, sign up here to receive every edition of BlueDot’s newsletter, Outbreak Insider.

The post The measles stress test: What 2025 taught us about global readiness appeared first on BlueDot.

Navigating the coming wave of influenza-like illnesses

Chantal Castro — Thu, 25 Sep 2025 15:31:48 +0000

The Northern Hemisphere’s flu season lurks around the corner. Better tracking, surveillance and analysis can help public health officials predict, plan and prevent.

Every fall and winter, influenza-like illnesses (ILIs) — including seasonal flu, respiratory syncytial virus (RSV) and the less predictable COVID-19 — sweep the globe, driving widespread epidemics. Despite their anticipated occurrence, these illnesses are often underestimated as significant public health threats: they are the single largest source of infectious disease hospitalizations annually, applying significant pressures on health care costs and delivery.

The reality is staggering: annually, one billion cases of seasonal influenza alone are estimated worldwide. For up to five million people, influenza infection becomes severe, and tragically, up to 650,000 lives are lost each year. And reported cases are just the tip of the iceberg. Because ILIs are so common and most people show only mild symptoms, many do not access care — which is where cases are tracked. Whether cases are recorded or not, the total economic impact of ILIs is extensive, whether it be productivity loss from calling in sick or hospitalization with severe illness.

“ILIs are one of the biggest problems in infectious diseases globally,” says Dr. Mariana Torres Portillo, Head of Surveillance at BlueDot. “The ability to determine when they may emerge and predicting how big outbreaks might be is fundamental to fortifying our public health response.”

This edition of Outbreak Insider explores global trends in ILIs, including what to expect for the upcoming ILI season in the Northern Hemisphere, and how BlueDot’s cutting-edge tracking methodology and expertise can help.

How the COVID-19 pandemic makes ILI season less predictable

Influenza-like illnesses are a set of respiratory illnesses with overlapping symptoms including fever, cough, and sore throat, with influenza, respiratory syncytial virus (RSV), and COVID-19 being the most impactful in terms of severity and hospitalizations. Transmitted through air and direct or indirect exposure to an infected person or environment, these infections can vary in symptom onset, when and for how long an infected individual may be contagious, severity, and the most appropriate treatment.

Typically, ILIs have a seasonality, with the “flu season” occurring in the fall and winter. In the Northern Hemisphere, this is from October to May, while the Southern Hemisphere’s runs from April to September. Low temperature and humidity, along with movement indoors and reduced immunity, create the ideal environment for respiratory infections to circulate.

The typical seasonality of ILIs shifted in the wake of the COVID-19 pandemic, adding an element of unpredictability that has lasted for years. The US and Australia saw their 2022-23 flu season begin upwards of two months earlier compared with the 2017-2018 season. More recent data, however, suggests that ILI trends appear to be normalizing.

Using real-time event-based surveillance (EBS) and indicator-based surveillance (IBS), BlueDot’s proprietary tracking system is showing that the Southern Hemisphere is beginning to come out of their ILI season, with influenza cases decreasing. Several countries, including Chile, Argentina, and Uruguay, are still experiencing high RSV activity. The flu and RSV tend to circulate together and peak around a similar time. Compared to last year, this year’s peaks did not substantially differ in timing.

Southern Hemisphere influenza and RSV activity, 2024-2025

Source: BlueDot, September 14, 2025.

The total volume of cases varied from country to country. Compared to last year, Paraguay reported a 31.8% higher volume of influenza cases nationally, while Chile reported a 31.5% higher volume of RSV cases indicating a more intense season. Uruguay and Argentina, however, had lower RSV case magnitudes than previous years, while New Zealand is still seeing widespread respiratory virus activity, highlighting the still somewhat unpredictable nature of the flu and RSV.

COVID-19 is behaving differently. It tends to hover year-round and does not follow a highly predictable seasonality like other respiratory infections that have been around for much longer in the human population. The spread of new variants of SARS-CoV-2 (the virus that causes COVID-19) through populations with different levels of immunity to past variants still makes it harder to predict year-round, creating challenges for planning, monitoring, and updating vaccines.

Globally, COVID-19 cases have steadily increased, coinciding with ILI season peaks in the Southern Hemisphere. Among countries with available data, almost two-thirds reported an increase in COVID-19 activity in August compared to July, most of which are in the Americas (North and South), Europe, and Japan, indicating a new wave.

Growth rate ratio of COVID-19 case rate, July 28-Aug 24 vs. June 30-July 27, 2025

Source: BlueDot, August 24, 2025.

With new COVID-19 waves, new variants emerged. In Asia and Oceania, variant NB.1.8.1 spread quickly, while variant XFG began increasing in Europe and North America. Both have shown signs of evading immune system detection and elimination, while XFG is more dominant globally and increasing in prevalence. With the new school year underway in the northern hemisphere, the risk of further disease spread is expected to increase.

Impact of ILIs

Influenza-like illnesses result in a significant number of hospitalizations and deaths. Young children, older adults, individuals with weakened immune systems or disabilities, and people who are pregnant are at increased risk for more severe illness. Beyond the humanistic burden, seasonal ILIs result in immense healthcare resource use and associated costs. A 2024 US-based study showed that the median length of stay for influenza-related hospitalizations was 3-4 days, and the average cost per influenza-related hospitalization ranged from $11,384 to $14,494.

And when COVID-19 is thrown into the mix, the burden can stress the system beyond normal capacity. Tripledemic pressure, caused by the co-circulation of influenza, RSV, and COVID-19, strained healthcare systems in Latin America. In Chile, for example, pediatric and adult intensive-care unit occupancy rose sharply amid increased respiratory illnesses in late April.

The economic impact is high even among those who do not become severely ill. Indirect costs, such as those resulting from productivity loss, comprise nearly 90% of the flu’s economic burden. Up to 5 days of work are lost due to ILIs, and up to three-quarters of employees miss work for their own or a household member’s illness (called “absenteeism”). Many others continue working while sick (called “presenteeism”), contributing to spread in the workplace. Productivity loss is greater among those who are unvaccinated.

3 Top Takeaways

Trends in ILIs are starting to normalize. As the Southern Hemisphere comes out of its regular ILI season, influenza and RSV appear to be returning to pre-pandemic levels. Peaks are occurring at similar times, and national cases are generally of similar or lower volume.
COVID-19 is the ILI wild card. Unlike the flu and RSV, COVID circulates year-round. And its emergence when the flu and RSV are peaking can overwhelm healthcare systems. Variant dynamics are critical in tracking transmission, updating vaccines, and mounting a coordinated public health response.
ILIs create an enormous economic burden. From missing work (absenteeism) to more severe illness requiring hospitalization, ILIs cause substantial morbidity and subsequent economic impact every year. Public health measures are key in mitigating the effects of these infections on the healthcare system.

Given the immense burden of ILIs on health and the economy, strengthening public health and healthcare system preparation is paramount. Unsurprisingly, vaccination is the gold standard tool for reducing infection and its associated burden. In a recently published modeling study, a universal COVID-19 vaccination recommendation for 2025-2026 was predicted to prevent over 100,000 hospitalizations and 9,000 deaths across the US if there was similar vaccine uptake as observed in 2023-2024. A recommendation limited to only those over 65 years or immunocompromised, in comparison, would be expected to avert 28,000 fewer hospitalizations and 2,000 fewer deaths. (All scenarios assume 2023-24 vaccine uptake levels.) But ongoing vaccine hesitancy, confusion about the benefits of updated vaccination, and varying policies and access to preventatives present a challenge to preparedness, meaning it’s going to be important to know when and how big the inevitable waves may be.

Keeping an eye on ILIs

What do the recent Southern Hemisphere trends mean for the Northern Hemisphere’s upcoming flu season? Often, public health and healthcare professionals can look at trends from the most recent season in the opposite hemisphere in anticipation of what may emerge. Were there new variants of SARS-CoV-2, and what impact did they have? Was this year’s flu season particularly severe? Though these trends may not be the same across hemispheres due to factors such as population immunity and demographics, vaccine policies and uptake, and the ongoing evolution of the pathogens, it does help as a starting point in getting prepared.

Knowing when and how ILIs are circulating impacts crucial decisions that entail millions of dollars, including development and distribution of vaccines and antiviral medications, as well as hospital resource allocation. Closely monitoring ILIs may even detect impending pandemics. In fact, it was BlueDot’s tracking system that first identified and raised the alarms about COVID-19 — even before the WHO and the US Centers for Disease Control and Prevention (CDC).

See ILI Trends in Near Real Time

BlueDot offers a unified view of ILI activity to its clients, offering immediate access to ILI data. BlueDot captures and analyzes official sources, media reports, and wastewater data — all offered to clients on an always-on basis. Our endpoints automatically calculate key insights like incidence, trends, comparison to previous time periods, and other key transformations. Such insights can be easily pulled into internal systems, models and reports. Contact BlueDot to stay on top of what’s happening and what’s relevant to your organization.

“Many of BlueDot’s clients receive global ILI reports, which can be tailored to their geography,” says Torres Portillo. “Receiving both local and global trends every other week based on our surveillance data, or even real-time data feeds, gives them a head start in initiating action.” With infectious diseases, time is of the essence. And with a little more of it, the substantial toll on human health and economic consequences can be improved.

On our radar

Hand, foot, and mouth disease in Thailand: More than 48,000 cases of HFMD have been reported since the start of the year, marking a nearly 66% increase in cases compared to the same period last year. Cases have been linked to heavy rainfall and high humidity, which create an ideal environment for disease transmission. Despite being endemic, the surge of HFMD exceeds historical averages in magnitude, and the potential for complications highlights the importance of surveillance.
Leptospirosis in the US: On September 10, an alert was issued following the emergence of an unusual cluster of six cases in northwest Chicago. Up from the historical median of two cases yearly, the increase in this zoonotic bacterial disease has been linked to rodent exposure, highlighting the importance of rodent control in urban settings. Public health efforts are underway, especially for at-risk groups.
Plague in Mongolia: On September 3, one case of the plague was confirmed in Khövsgöl Province, where the disease is endemic. Six days later, a total of three cases and one death had been reported — exceeding the yearly average. This zoonotic bacterial disease can present in the form of the bubonic, pneumonic, or septicemic plague, and it spreads via contact with infected fleas or rodents. Authorities have strengthened surveillance and enforced temporary lockdowns and closures.

Need to keep up to date on emerging infectious disease outbreaks? BlueDot’s Event Alerts provide the lowdown on outbreaks around the world, delivered to your inbox and tailored to your location and your preferences. Contact BlueDot to stay on top of what’s happening and what’s relevant to your organization.

As ILIs wane in the Southern Hemisphere and pick up speed in the Northern Hemisphere, tracking cases, identifying trends, and anticipating risk is paramount to ensure public health and healthcare systems are equipped to handle outbreaks. BlueDot’s indicator- and event-based surveillance combines data from multiple sources — including wastewater data from across the United States — and can provide details at the regional level, offering a measure of customization for its clients’ priority locations. Combined with ILI Pulse reports offering expert insights, public health practitioners and healthcare professionals can access a tailored view of worldwide infectious disease activity trends.

To stay updated on all the latest infectious disease news, sign up here to receive every edition of BlueDot’s newsletter, Outbreak Insider.

The post Navigating the coming wave of influenza-like illnesses appeared first on BlueDot.

Chikungunya goes global

Chantal Castro — Thu, 11 Sep 2025 15:33:34 +0000

Once largely confined to Africa, the disease has taken hold in all parts of the world — with consequences for travelers and public health alike

The spread of chikungunya, the mosquito-borne disease that causes debilitating joint pain, has resulted in more than 270,000 cases and 110 deaths to date in 2025 across southeast Asia, Europe and the Americas. As cases continue to rise, the World Health Organization has issued an alert for a potential global chikungunya epidemic — a surprising turn of events for a disease usually considered regional in nature.

As of mid-August, about 120 countries are affected and more than five billion people are at risk. Cases have been both imported and locally-acquired in new locations, highlighting the risk of global travel and the growing concern of increased vector suitability and expanded habitats as the climate changes. For public health officials, that can mean increasing their surveillance for imported cases, educating local medical professionals on the likelihood of local cases, and even implementing vector control measures.

“Chikungunya is a major public health risk that is expected to keep spreading to new locations,” says Andrea Thomas, PhD, BlueDot’s Head of Epidemiology. “The key to prevention is knowing where it’s most likely to emerge next.”

This edition of Outbreak Insider dives into where chikungunya outbreaks are occurring, where risk of infection is heightened, and what public health officials can do to assess the risk level in their region.

Chikungunya: the lowdown on an alarming arbovirus

First discovered in Africa in the early 1950s, chikungunya is a vector-borne disease caused by a virus of the Togaviridae family. The illness is transmitted by the Aedes mosquito, an aggressive species most active during the day. These mosquitoes tend to live in close proximity to humans and thrive in warm and wet conditions across tropical, subtropical, and temperate climates.

The name “chikungunya” is based on the Kimakonde words for “to become contorted,” a reference to its most tell-tale symptom: severe joint pain. For up to 40% of those infected, joint pain is chronic. However, the disease’s often-mild initial presentation, and its overlapping symptoms with other arboviruses like dengue and Zika — fever, headache, rash, fatigue — make it challenging to identify. There are an estimated 35.3 million infections around the world annually, of which barely half (17.7 million) are symptomatic. Chikungunya is estimated to cause 848,000 chronic sequalae, 3,700 deaths, and 121,000 disability-adjusted life years (DALYs) lost every year.

Climate change, increased global travel, urbanization and land use changes, and decline in global surveillance investment are among the key factors responsible for the recent explosion of chikungunya and other mosquito-borne diseases. Climate change is a notable driver of disease as rising temperatures, longer summers, milder winters, and changes in rainfall patterns increase the geographic range in which mosquitoes can thrive.

And where Aedes mosquitoes are present, there’s a high correlation that chikungunya is as well. The virus has now made landfall on most continents. Unlike dengue, which has predicable seasonal patterns, chikungunya is cyclical, rising and falling over multi-year intervals — and when outbreaks occur, they can be sporadic and explosive. Well over half of the world’s countries, largely in Africa, Asia, and the Americas, are reporting cases. And today, the virus is establishing a foothold in Europe.

Source: BlueDot, September 2025.

Chikungunya in 2025: a disease spreads its wings

In the first half of 2025, BlueDot issued alerts for outbreaks in Réunion, Mayotte, and Mauritius, where more than 50,000 cases have been reported since August of last year. India, where the virus is endemic, was the center of an atypical spike in cases last fall with a historical 180,000 laboratory-confirmed cases. And nearby Sri Lanka is also battling widespread cases with unique genetic findings that help the virus spread more easily and evade immune system detection.

Outbreaks in the Indian Ocean region have spread to Africa and Europe, including in France, Russia, and Germany. Travel-related cases have prompted the United Kingdom Health Security Agency and the US Centers for Disease Control and Prevention (CDC) to issue travel warnings and precautions. BlueDot’s air connectivity analysis — which clients use to model the risk of imported cases between travel hubs for any part of the world — found that outbreaks in India had a high risk of spread to the United Arab Emirates, and moderate risk of spread to the UK, US, and Singapore, among others.

3 regions with major chikungunya outbreaks in 2024-25 and their connectivity to North American and European travel hubs

Source: BlueDot, September 2025.

The virus’ introduction to areas with large, immunologically naïve populations means the disease can be transmitted quickly, and fiercely.

China — which experienced a combined total of 519 chikungunya cases from 2010 to 2019 —has reported more than 10,000 cases of chikungunya since July of this year, marking the country’s largest recorded outbreak. At its peak, over 600 new infections were being reported daily. The epicenter is Guangdong, the southeast Chinese province that also happens to be the nation’s most populous.

Despite China’s efforts to clear mosquito breeding grounds, spray insecticide, and establish mosquito-proofing efforts, imported cases have been detected in Taiwan, Macau, and Hong Kong. This has prompted travel advisories to be issued for southern China. BlueDot’s air connectivity also indicates high connectivity risk to Malaysia and Thailand, and moderate connectivity risk to Japan, South Korea, and Cambodia. For some of these countries, an outbreak would strain an already resource-limited healthcare system.

Europe, whose populations are also naïve to chikungunya, has seen a record-breaking 27 outbreaks this year as of August 20, a combination of both local and travel-related transmission. The Alsace region in northeastern France recorded its first-ever locally acquired case this year, meaning transmission risk is expanding northward. The presence of Aedes albopictus, one of the two types of mosquitoes that carry the virus, has now been established in 16 European countries and 369 regions — an increase from 114 regions just ten years ago.

Get real-time coverage of fast-moving diseases

Over the past 18 months, BlueDot has sent over a dozen alerts to our clients on the global spread of vector borne diseases including dengue, chikungunya, zika and malaria. We’ve tracked cases from recently affected areas like Russia, Spain and the United States. Our alerting complements our ongoing, up-to-date case data on these diseases, which syncs official sources and media reports in a single experience.

In the Americas, a suspected 212,029 cases and 110 deaths were reported between January and mid-August. Since the disease arrived on the shores of the Americas in 2013, Brazil has consistently experienced the highest case counts in the world, reporting more than one million cases since 2019. From 2020 to 2024, there has been a 41.5% average year-on-year increase in chikungunya cases.

A 2024 analysis conducted by BlueDot found that global travel advisories for chikungunya in Brazil decreased over time despite an increase in yearly cases. Since travel advisories are typically issued for new outbreaks — not ongoing endemic activity — a gap emerged in travel advisory issuance and actual disease activity. Given Brazil’s high connectivity to North America, public health officials need up-to-date intelligence to reassess their local and regional needs for extra precautions in preventing illness and monitoring imported cases.

3 Top Takeaways

Global chikungunya cases have become a game of Whack-A-Mole. From Asia to the Americas, record-breaking outbreaks have been reported. This sporadic, unpredictable, and explosive mosquito-borne disease has popped up in expected and unexpected places largely due to global travel and climate change.
Connection to chikungunya is too close for comfort. Imported and locally acquired cases are emerging in endemic and non-endemic areas, leaving more than 5 billion people at risk of infection. BlueDot’s air and ground connectivity analysis shows the most connected locations in Europe and North America to global outbreaks.
Mobilizing preventive tools can mitigate mosquito-borne diseases. Predicting risk and establishing connectivity to hotspots can lead to decreased chikungunya infections, thereby reducing the associated disease burden.

Arboviral awareness

Chikungunya presents both public health officials and workplace health and safety directors with a potentially immense patient and economic burden. Between 2011 and 2020, chikungunya’s 18.7 million global cases and resultant 1.95 million DALYs amounted to an estimated $50 billion USD in total economic burden. Of this, $2.8 billion was attributed to direct costs, and $47.1 billion in indirect costs, most notably absenteeism. And a global epidemic of chikungunya in the months ahead would not be its first.

All of which underlines the importance of regional risk assessment for chikungunya. Some interventions, such as physician education and increased vigilance for imported cases, can be implemented through existing local practices. Funding for vector control programs, on the other hand, tends to be cyclical and reactive — meaning that regions newly at risk of local chikungunya transmission could be facing significant budget pressures, increased costs, and response delays.

“BlueDot’s clients in the public health sector are leveraging our surveillance data and predictive tools with other official sources to better serve their populations,” says Thomas. “The intelligence they get as a result is timelier and more comprehensive than traditional approaches.” With the best infectious disease intelligence, public health authorities and healthcare professionals can keep their finger on the pulse and protect countless people from illness.

On our radar

Ebola in the DRC: In early September, 28 suspected cases and 16 deaths were reported, confirming a new outbreak of Ebola in the Democratic Republic of the Congo. Response teams have been deployed, along with two tonnes of supplies and 2000 doses of the Ervebo vaccine. The genomic evidence, swiftly provided by DRC officials within 24 hours of the outbreak declaration, indicates a new zoonotic spillover event from an unknown reservoir host, underscoring the continuous threat of outbreaks in this region.
Eastern Equine Encephalitis in Canada: Canada saw its first human case of EEE in Hamilton, Ontario, among a man with no recent travel history, meaning the case was likely locally acquired. Two horses in the area were also confirmed to have the mosquito-borne virus, further indicating local exposure and risk. Although rare, cases in 2024 and 2025 suggest vector habitats have expanded, and exposure to the disease may increase with climate change and lengthened mosquito seasons.

Need to keep up to date on emerging infectious disease outbreaks? BlueDot offers daily reporting, tailored to your location and your preferences, that can be delivered to your inbox or synced to your internal reporting tools. Contact BlueDot to get real-time data on what’s happening and what’s relevant to your organization.

BlueDot’s indicator- and event-based surveillance, regional connectivity analyses, and expert insights into hotspots and areas of increasing risk complement travel advisories and local responses, giving public health experts and healthcare professionals a more holistic view of infectious disease activity.

To stay updated, sign up here to receive every edition of BlueDot’s biweekly newsletter, Outbreak Insider.

Curious to learn how BlueDot saves clients hours per day tracking infectious disease? Click here to connect with us.

The post Chikungunya goes global appeared first on BlueDot.

Cholera crisis hits a tipping point

Chantal Castro — Thu, 31 Jul 2025 15:46:04 +0000

Climate, conflict, and crumbling infrastructure are fueling the rapid global spread of the deadly bacterial disease

Cholera, the waterborne bacterial disease that spurred the construction of urban sanitary sewers and waterworks in the 19th century, is once again becoming a scourge to global health.

Last month, 62,330 new cases of cholera and/or acute watery diarrhea (known as AWD, of which cholera is the most frequent cause), and 527 cholera-related deaths were reported across 20 countries and territories around the world. Global cases since January have already surpassed 300,000 and led to 3,500 deaths. And for the first time in half a year, the cholera vaccine stockpile fell below the necessary emergency reserve, threatening global capacity to respond as outbreaks intensify.

Following years of declining cholera cases, the bacterial infection made a resurgence in 2021. Since then, yearly outbreaks have only worsened. Twenty-eight countries have reported outbreaks so far this year, with the majority of cases in the Eastern Mediterranean and African regions. And those outbreaks are becoming increasingly deadly. Despite lower case counts compared with June 2024, deaths this year are up 38%, pointing to gaps in timely access to care.

Humanitarian crises caused by events such as floods and armed conflict are major drivers of increased cholera risk, as they impair healthcare infrastructure and limit access to urgently needed care. Up to 4 million cases and 143,000 deaths are estimated every year, and more than 1 billion people are at risk for infection. Both the WHO and the Africa Centres for Disease Control and Prevention (CDC) have sounded the alarms. And recent evidence points to circulation of antimicrobial resistance in cholera, further compounding widespread outbreaks and containment challenges.

“Antimicrobial-resistant cholera is likely circulating in countries with the largest outbreaks, where diagnostic capabilities are limited,” says Dr. Mariana Portillo Torres, BlueDot’s head of surveillance. “Without appropriate diagnosis, ineffective antibiotics may be prescribed, meaning people are not only receiving suboptimal treatment but antibiotic resistance is exacerbated.”

Given the sharp and sustained rise in cases, and the emergence of antimicrobial-resistant strains, cholera outbreaks are expected to worsen — and it will take sustained effort to contain them.

Global cholera cases are spreading faster and becoming deadlier

Cholera is a bacterial disease caused by Vibrio cholerae transmitted through the ingestion of contaminated water or food, one with a remarkable history as both a health menace and a catalyst of human ingenuity. The disease originated in South Asia and spread widely in the 19th century, the result of ships transporting contaminated bilge water from the Bay of Bengal. Cholera was the main driver of the mid-19th century sanitation movement in Europe and its colonies, leading to the establishment of sewage systems and clean water provisions in many parts of the world.

Today, those most at risk live in locations still without access to safe drinking water, sanitation, or hygiene. Not everyone who gets cholera becomes ill. But for ten percent of people, cholera can lead to life-threatening watery diarrhea and vomiting, quickly causing dehydration and shock. If untreated, it can kill people within hours.

Between January and June 2025, 305,903 cases and 3,522 deaths have been reported across 28 countries. The hardest hit regions are the Eastern Mediterranean (159,414 cases, a region which encompasses the Arabian peninsula and its surroundings), Africa (143,762 cases), and South-East Asia (2,727 cases). Of these, cases are most widespread in Africa, with 19 countries reporting cases. Actual case counts are likely higher as reports are delayed or the disease goes underreported.

Cholera and AWD cases per 100,000 cases, Jan. 1-June 29, 2025

Source: World Health Organization, Multi-country Outbreak of Cholera External Situation Report n. 28, published July 24, 2025.

The fight against cholera led to declining cases for several years. But in 2021, cases began rising as the COVID-19 pandemic, along with climate-related disasters and conflicts, disrupted health systems. In 2022, more than 30 countries reported outbreaks — twice the usual amount — prompting the WHO and Global Task Force on Cholera Control (GTFCC) to officially recognize a multi-country resurgence.

In January 2023, the WHO labelled cholera a Grade 3 Emergency, its highest level, as countries such as Malawi, Mozambique, and Syria faced their worst outbreaks in decades amid depleted vaccine stockpiles. Climate events and conflict worsened outbreaks across Africa, Asia, and parts of the Americas in 2024, which saw a 50% increase in cases over the year prior. Outbreaks have also become deadlier, leading to the decade-high case fatality rates.

Cholera Cases and Deaths, 2021- 2024

Source: BlueDot, July 2025. Data source: WHO, created with Datawrapper.

Particularly hard hit this year are Angola (27,033 cases), Democratic Republic of the Congo (DRC; 34,192 cases), South Sudan (62,903 cases) and Sudan (32,359 cases) in Africa and Afghanistan (68,031 cases) and Yemen (42,162 cases) in the Eastern Mediterranean. Several of these have contributed to the 29 new emergency requests seeking vaccine doses between January and June, up from nine last year. The Africa CDC has identified cholera as a top challenge, and cholera outbreaks are rapidly moving toward a health emergency of regional concern.

Often, several concurrent diseases simultaneously overwhelm available health services. In Yemen, for example, an 87% increase in cholera cases was reported last month compared with May as the nation also combatted co-circulation of both measles and dengue. Similarly, South Sudan is navigating its worst and longest cholera outbreak while also confronting regional outbreaks of mpox, hepatitis, and measles. Outbreaks are further complicated by low vaccination rates, such as in Sudan, where cholera vaccine coverage is only 5.6%.

Europe’s risk for cholera is low as it does not confront the same sanitation and hygiene challenges. Yet, the region has seen a few cases linked to travel or exposure tied to at-risk regions. For example, four domestic cases in Germany and the UK emerged in February 2025 following the ingestion of holy water imported from Ethiopia.

Complex factors combine to increase cholera risk

Ongoing outbreaks are a complex interplay of several factors. At the forefront is unsafe water, poor sanitation, and inadequate hygiene practices. These intersect with socioeconomic factors such as rapid urbanization and lack of public health education, as well as health system capacity factors such as limited surveillance and prevention and treatment measures. These disproportionately affect poorer nations and underscore health inequities.

Political instability and conflict make matters worse as they lead to population displacement, further poverty, and devastated infrastructure and health systems. Countries such as the DRC, Sudan, and Yemen are seeing cases spike as conflict forces people into areas without access to clean water or sanitation, and renders the health system largely nonfunctional.

And though not a direct cause of increased cholera risk, climate change has a similar effect, driving people out of their homes into overcrowded shelters with makeshift sanitation and poor hygiene, all while limiting access to care. Both South Sudan and the DRC have been experiencing flooding, affecting availability of clean water, sanitary environments, and basic health services. Both conflict and climate disasters make diagnosis and treatment become difficult, which can lead to serious illness and death.

Factors Driving Increased Cholera Risk

Source: Global Task Force on Cholera Control [site].

A recent report also confirmed the appearance of a cholera strain resistant to 10 antibiotics, including common treatments such as azithromycin and ciprofloxacin, in East Africa. Antimicrobial-resistant strains have contributed to recent years’ rampant outbreaks, and experts fear that additional resistance would compromise all available oral antibiotics. With diagnostic limitations in some of the most afflicted nations, patients may be treated with ineffective antibiotics, contributing to greater potential for antimicrobial resistance. With no new cholera treatments in the pipeline, this poses a massive risk in the efforts to control cholera outbreaks.

3 Top Takeaways

Cholera cases and deaths continue to climb. June saw 62,330 cholera and/or acute watery diarrhea (AWD) cases and 527 deaths. Since the start of the year, there have been 305,903 cumulative cases and more than 3,500 deaths across 28 countries. The hardest hit regions are the Eastern Mediterranean, Africa, and South-East Asia.
Conflict and climate change fuel increasing cholera cases. Resurging outbreaks of this vaccine-preventable disease are driven by conflict and climate change events such as floods and droughts, which limit access to clean water, sanitation, and healthcare access. One billion people are at risk of infection as outbreaks exceed the response capacity, including a drop in the emergency vaccine stockpile.
Antimicrobial cholera strains compound challenges with disease control. Drug-resistant strains of cholera have been identified and are believed to be contributing to surging cholera cases. However, impaired diagnostic capacity in many affected countries means circulating strains are unknown and inappropriate treatments are being given — further worsening the issue of antimicrobial resistance.

Containing cholera calls for collaborative response

Cholera is a preventable disease. Of utmost importance in curbing spread is improved water, sanitation, and hygiene (WASH) infrastructure. But funding gaps, both regionally and internationally, and lack of prioritization outside of emergency situations have allowed the bacterial disease to circulate beyond cholera-endemic regions. For example, only 16% of African countries have fully funded National Cholera Plans and 31% have implemented water quality interventions as country-level commitment remains variable.

Vaccine supply shortages, caused by increased demand and manufacturing constraints, are increasing vulnerability as populations go undervaccinated in both preventive and reactive settings. Between January 2023 and July 2024, 102 million doses of the Oral Cholera Vaccine were requested despite only 51 million doses produced amid complete depletion of the global stockpile. With last month’s stockpile at 2.9 million — far below the emergency stockpile threshold of 5 million doses — the global capacity to respond is stretched thin.

“There are just so many forces acting against cholera prevention,” says Andrea Thomas, PhD, BlueDot’s head of epidemiology. “But cholera is a solvable problem — it’s not out of our hands.” Despite confronting many ongoing outbreaks and limited resources, the Africa CDC has spearheaded the response to cholera, coordinating efforts from local and international bodies to work toward cholera elimination by 2030.

From calls for robust investment into WASH and timely access to prevention, diagnostic, and treatment measures, efforts are already beginning to materialize. Facilitated by the WHO, more than 50 institutions have formed the GTFCC to provide real-time data, centralize technical guidance and training resources, and offer country-specific support. With commitment to the 2030 cholera elimination roadmap, the prospect of a global cholera pandemic may be prevented.

On our radar

Chikungunya in China: During a one-week window in late July, 2,940 new cases of chikungunya were reported in Guangdong province, bringing Guangdong’s total case count for the year to 4,824 as of July 26. The surge indicates ongoing mosquito-to-human transmission amid reports of strained public health infrastructure. Chikungunya’s regional spread has been confirmed in bordering Macau, where at least two exported cases have been reported, while the Hong Kong Centre for Health Protection enhances control point inspections. The presence of the Aedes albopictus vector underscores the risk of a wider outbreak.
Acute Flaccid Myelitis in Gaza: Between May and July, 45 cases of acute flaccid paralysis (AFP) were reported in Gaza. A syndrome marked by sudden limb weakness progressing to paralysis, AFP may signal undetected polio — a serious viral infection that affects the nervous system. The ongoing conflict and humanitarian crisis increase the risk for infectious disease spread and further health system collapse, which affects disease prevention, diagnosis, and treatment.
Malaria in Romania: A case of malaria was confirmed in Bucharest, Romania, on July 10 among a patient with no recent international travel history — potentially an indigenous case of the mosquito-borne illness. If found to be indigenous, this would be the first such case in over 60 years. By July 10, 21 travel-reported cases had been reported, increasing the risk of reintroduction in the nation. The source of infection is under investigation, as is the risk of broader transmission.

A final note

BlueDot’s biweekly newsletter, Outbreak Insider, is on summer holiday for the month of August. We know infectious diseases don’t stop circulating, so we’ll be back to get you caught up to speed in September. In the meantime, sign up here — we’ll see you in a few weeks refreshed and ready to bring the most important infectious disease news!

The post Cholera crisis hits a tipping point appeared first on BlueDot.

BlueDot

What can we learn from Measles in the US?

The largest US measles outbreak in over 25 years is unfolding, exposing a complex dynamic between risk, hesitancy and vaccination. Organizations everywhere can learn much from it.

The Coverage Picture

"It's not that bad"

On our radar (spotlight on Measles)

Measles in South and Central America

Other Measles Outbreaks in Early 2026

The US Risk Map

Why Coverage is Falling

Who refuses — and why

A window that closes

The practical gap

Who is trusted

Key Takeaways

Beware the “Superflu” hype: How infectious disease surveillance goes beyond the headlines

When it comes to outbreaks, media reporting is a critical resource—but its trade-offs cannot be ignored

There’s a lot of noise about this year’s flu and ILI activity. Let’s cut through it.

3 Top Takeaways

On our radar

Tracking Infectious Threats: Key Outbreaks of 2025 and Risks for 2026

The most notable infectious disease events of 2025

Three battles we fought — and another we won — against emerging threats and resurgent foes over the past year

Evading an Ebola emergency

Setbacks on the frontlines

Cholera and AWD cases per 100,000, Jan. 1-Oct. 26, 2025

Measles Incidence in 2025 and Vaccination Coverage with a Second Dose of Measles-Containing Vaccine for 2024, January 1 to December 15, 2025

Global chikungunya outbreak status and total reported cases, Jan. 1, 2024-Dec. 10, 2025

3 Top Takeaways from 2025

Start the new year by getting ahead of emerging threats

Forecasting infectious diseases in 2026

Stay ahead of what’s next

On our radar

How data blackouts and blind spots put organizations at risk

The U.S. government shutdown demonstrates how infectious disease data sources can dry up — and how third-party surveillance sees in the dark

A synopsis of disease surveillance history and challenges

When the dashboard goes dark

Get trusted, near real-time visibility to fill in the data gaps

War obscures warning signs

3 Top Takeaways

Blurred Borders

Closing the surveillance gap

BlueDot’s Global Disease Surveillance Engine

On our radar

Local Matches, Global Risks: Infectious Disease Surveillance, Connectivity and the 2026 World Cup

The measles stress test: What 2025 taught us about global readiness

North America teeters on the edge of losing measles-free status, proving that disease elimination is not a finish line but a maintenance task

From elimination to escalation: North America’s measles revival

Where coverage falters, measles flares

Measles Incidence in 2025 and Vaccination Coverage with a Second Dose of Measles-Containing Vaccine for 2024, January 1 to October 21, 2025

3 Top Takeaways

Calculating connectivity

What does your region’s risk map look like?

On our radar

Navigating the coming wave of influenza-like illnesses

The Northern Hemisphere’s flu season lurks around the corner. Better tracking, surveillance and analysis can help public health officials predict, plan and prevent.

How the COVID-19 pandemic makes ILI season less predictable

Southern Hemisphere influenza and RSV activity, 2024-2025

Growth rate ratio of COVID-19 case rate, July 28-Aug 24 vs. June 30-July 27, 2025

Impact of ILIs

3 Top Takeaways

Keeping an eye on ILIs

See ILI Trends in Near Real Time

On our radar

Chikungunya goes global

Once largely confined to Africa, the disease has taken hold in all parts of the world — with consequences for travelers and public health alike

Chikungunya: the lowdown on an alarming arbovirus

Chikungunya in 2025: a disease spreads its wings

3 regions with major chikungunya outbreaks in 2024-25 and their connectivity to North American and European travel hubs

Get real-time coverage of fast-moving diseases

3 Top Takeaways

Arboviral awareness

On our radar

Cholera crisis hits a tipping point

Climate, conflict, and crumbling infrastructure are fueling the rapid global spread of the deadly bacterial disease

Global cholera cases are spreading faster and becoming deadlier

Cholera and AWD cases per 100,000 cases, Jan. 1-June 29, 2025

Cholera Cases and Deaths, 2021- 2024

Complex factors combine to increase cholera risk

Factors Driving Increased Cholera Risk

There’s a lot of noise about this year’s flu and ILI activity.
Let’s cut through it. 