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Chikungunya, a viral infection caused by an alphavirus that is spread to people through the bite of an infected female Aedes mosquito, significantly impacted the Americas and the European region in 2025.
According to the World Health Organization (WHO) latest report, a total of 445,271 suspected and confirmed Chikungunya cases and 155 related fatalities worldwide. The distribution of cases across regions has been uneven, with some countries reporting a resurgence in numbers during 2025.
The French Overseas Departments in the Indian Ocean, such as La Réunion, are Europe's unfortunate leader in Chikungunya outbreaks in 2025.
The WHO wrote that the potential for further geographical spread is highlighted by the fact that 27 countries and territories have established competent vector populations (Aedes aegypti and Aedes albopictus mosquitoes) but have not yet documented local Chikungunya transmission.
In the United States, as of November 11, 2025, 88 travel-related Chikungunya cases have been confirmed by the U.S. CDC.
The state of Florida, which is geographically located near endemic areas such as Cuba, has reported 42 travel-related Chikungunya cases confirmed this year in Broward, Collier, Lake, Miami-Dade, Palm Beach, and Seminole Counties.
And recently, the New York State Department of Health confirmed a locally acquired case of Chikungunya in Nassau County.
The CDC does recommend Chikungunya vaccination for specific international travelers in 2025.
Japanese encephalitis virus (JEV) is the leading cause of epidemic encephalitis worldwide and is prevalent across Asia and the Pacific.
A recent study published in the journal Nature highlights significant public health concerns stemming from changes in the dominant genotype, the emergence of epidemics in new regions, and the re-emergence of previously dormant genotypes.
The re-emergence of specific genotypes in Indonesia after 37 years, coupled with JEV-related fatalities in Australia, Nepal, and Taiwan, highlights the need for critical control measures.
Nepal's Department of Health Services has confirmed 164 cases of Japanese encephalitis in 2025, compared to 86 last year.
In 2024, 23 people died in Nepal infected with the JEV.
Similarly, the resurgence of genotype in China after 57 years and its circulation in Korea underscore the need for continuous surveillance and proactive vaccinations.
According to the U.S. CDC, a Japanese encephalitis vaccine (IXIARO) is available in the United States, approved for use in children aged 2 months and older and adults.
The CDC says this approved vaccine should be considered for some travelers before visiting high-risk areas in 2025.
In the United States, IXIARO is commercailly offered at travel clinics and pharmacies.
According to the Global Polio Eradication Initiative (GPEI), 2 billion doses of the novel oral polio vaccine type 2 (nOPV2) have now been administered to children around the world, primarily in Africa.
Since the WHO approved its use in 2020, the nOPV2 vaccine has been an essential part of intensified efforts to curb outbreaks of circulating type 2 variant poliovirus (cVDPV2) in 35 countries. It has been 'triple-locked' through genetic engineering to prevent it from becoming harmful or producing mutations, says the GPEI.
The U.S. CDC Advisory Committee on Immunization Practices presentations on February 28, 2024, included an Introduction and Considerations for the Potential Use of nOPV2 as an Outbreak Control Measure in the U.S.
The CDC currently publishes a Level 2 Travel Health Notice regarding the risk of polio in 39 countries.
As of November 10, 2025, the IPV polio vaccine is offered in the United States, and booster doses are recommended for specific international travelers.
Currently, no vaccines or therapeutics are licensed against Lassa fever, an acute viral hemorrhagic illness caused by Lassa virus (LASV) that is responsible for thousands of deaths each year across West Africa, where the disease is endemic.
The findings from a first-in-human, Phase 1 clinical trial of IAVI's LASV vaccine candidate, published in the New England Journal of Medicine on November 6, 2025, demonstrate that one dose of the vaccine elicits robust and long-lasting immune responses and has an acceptable safety profile.
"Lassa fever is a cruel disease which has plagued West Africa for decades, including a deadly outbreak in Nigeria this year," said Dr. Kent Kester, Executive Director of Vaccine R&D at CEPI, in a press release.
"The promising Phase 1 data for IAVI's vaccine candidate takes us one step closer towards a much-needed Lassa fever vaccine, which, if successful, could save thousands of lives and avert millions of dollars of societal costs in the West African countries that bear the burden of this disease."
The Pan American Health Organization (PAHO) today announced Canada has lost its measles elimination status, which was attained in 1998.
According to the PAHO press release on November 10, 2025, Canada can re-establish its measles status once transmission of the measles virus has been interrupted for at least 12 months.
During 2025, over 80% of Canada's 5,162 measles cases were reported in Ontario and Alberta.
Currently, the U.S. CDC advises all people traveling to Canada to ensure they are fully vaccinated against measles.
The Israeli Ministry of Health recently reported the ninth measles-related fatality in a child since an outbreak began earlier in 2025.
On November 9, 2025, a child from Jerusalem with an underlying health condition, who had received one dose of the measles vaccine, passed away at an emergency department due to complications from the disease.
As of today, 16 patients are hospitalized after contracting measles.
Until now, all previous measles cases involved healthy infants with no underlying conditions who were unvaccinated.
The Ministry of Health reiterated in a press release that measles is preventable with a safe and effective vaccine. It emphasizes the importance of seeking medical care promptly if symptoms appear or if exposure to measles is suspected.
Since May 2025, the U.S. CDC has included Israel in its Global Measles travel advisory.
The CDC says all international travelers should be fully vaccinated against measles before departing abroad. Measles vaccination services are offered at travel clinics and pharmacies in 2025.
