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The H5N1 strain of highly pathogenic avian influenza (HPAI) has been present in wild birds worldwide and caused outbreaks in U.S. domestic birds and dairy cattle in 2024-2025.
While there were 70 humans infected with HPAI, and one related fatality, there was no human-to-human transmission of this serious virus.
However, since February 25, 2024, only six human cases have been reported.
As the number of infections has recently decreased, the U.S. Centers for Disease Control and Prevention (CDC) announced that it has streamlined H5N1 bird flu updates with routine influenza data and reporting cadences to reflect the current public health situation.
As of July 7, 2025, the following changes were made to this CDC webpage:
Data on the number of people monitored and tested for bird flu are reported on a monthly basis.
Data on highly pathogenic avian influenza (HPAI) detections in animals will no longer be reported on the CDC website. These HPAI data can be found on the U.S. Department of Agriculture's website.
Furthermore, the CDC will report any additional human cases of H5 bird flu here and in FluView.
While there are 'bird-flu' vaccines approved by the U.S. FDA, none were deployed in the USA during this outbreak.
During the first half of 2025, Canada's measles outbreak occurred primarily in rural areas of Ontario.
Recently, however, there has been a rising number of measles cases reported in Western Canada.
As of the end of June 2025, specifically during week #26, the province of Alberta reported 104 new measles cases. This brings the total number of people infected with the measles virus this year to 1,169.
To facilitate patient care in Alberta, the Ministry of Primary and Preventive Health Services was established on May 16, 2025.
Additionally, the Alberta Immunization Policy contains a comprehensive listing of publicly funded vaccines and biologicals, along with indications for their use, including the measles-mumps-rubella (MMR) vaccine.
As of July 8, 2025, Canada recommends MMR vaccination for most people.
To alert international travelers, the U.S. CDC updated its Global Measles Outbreak Travel Health Advisory on May 28, 2025. This Level I advisory includes Canada.
The CDC wrote, 'All international travelers should be fully vaccinated against measles with the MMR vaccine, according to CDC's measles vaccination recommendations for international travel.'
Over the past decade, numerious herpes zoster cases were prevented with two doses of a U.S. FDA-approved vaccine that contains an adjuvant. According to new research, there may be an additional, measurable benefit from vaccination.
A Brief Communication published by NPJ Vaccines on June 25, 2025, reported a lower risk of dementia associated with AS01-adjuvanted vaccination against shingles.
In propensity-score matched cohort studies involving 436,788 individuals, both the AS01-adjuvanted shingles and respiratory syncytial virus vaccines, administered individually or in combination, were associated with a reduced risk of dementia at 18 months.
AS01 may protect against dementia through specific immunological pathways.
In particular, stimulation of toll-like receptor 4 with monophosphoryl lipid A (MPL; one of the components of the AS01 system) has been shown to improve Alzheimer’s disease pathology in mice.
In addition, the two main ingredients of AS01, MPL and QS-21 (a purified plant extract derived from Quillaja saponaria), act synergistically to activate macrophages and dendritic cells, triggering an age-independent cytokine cascade that culminates in the production of interferon gamma (IFN-γ).
IFN-γ might attenuate amyloid plaque deposition (as seen in mice) and is negatively correlated with cognitive decline in cognitively unimpaired older adults.
These neuroprotective mechanisms may reach their full potential at or below the dose of AS01 administered within a single vaccine, so that administering both the AS01 shingles and RSV vaccines does not provide any additional benefits.
This saturation effect could also explain why the level of protection against dementia appears similar between the AS01 shingles vaccine (which is given in two doses) and the AS01 RSV vaccine (administered as a single dose).
No difference was observed between the two AS01-adjuvanted vaccines, suggesting that the AS01 adjuvant itself plays a direct role in reducing the risk of dementia.
A previous study found similar cross-protection benefits.
In July 2024, a University of Oxford-led study concluded that receiving the recombinant Shingrix® vaccine was associated with a 17% increase in diagnosis-free time, translating into 164 additional days lived without a diagnosis of dementia in those subsequently affected.
As of July 7, 2025, shingles vaccination services are offered at most pharmacies in the United States.
According to the health departments of various countries, a cluster of vaccine-derived poliovirus type 2 (cVDPV2) has been detected in wastewater samples collected in Europe.
As of July 7, 2025, the European Centre for Disease Prevention and Control (ECDC) says these countries include, but are not limited to, the United Kingdom, Finland, Germany, Spain, and Poland.
Specifically, Germany has reported detections of cVDPV2 in multiple environmental samples throughout 2024 and the first half of 2025.
In 2024, a strain of variant poliovirus originating from Nigeria was repeatedly detected in wastewater samples from Hamburg, Berlin, Munich, Frankfurt, Stuttgart, Dresden, Cologne, Düsseldorf, and Bonn.
In 2025, detections have been from Dresden during weeks 17, 19, 21, and 23, Mainz during weeks 15 and 19, Munich during weeks 21, 22, and 23, and Stuttgart during week 21.
The cluster exhibits a degree of genomic diversity that more strongly supports the hypothesis of multiple introductions than a single introduction with local transmission within the EU.
However, the large geographical spread in the EU/EEA, the fact that detections occurred over several months, and the identification of specific genetic sub-clusters suggest at least some degree of local transmission.
Fortunately, no cases of poliomyelitis have been reported in Europe.
The last indigenous case of polio in Germany was in 1990.
Given the presence of non-vaccinated or under-vaccinated population groups in European countries, and the fact that poliomyelitis has not been eradicated globally, the risk of the virus being reintroduced into Europe remains, affirms the ECDC.
To alert international travelers visiting Europe during the summer of 2020, the U.S. CDC's Level 2 - Practice Enhanced Precautions, Travel Health Advisory identifies 41 countries at risk for poliovirus detections.
According to the CDC, travelers to Germany are at increased risk of exposure to poliovirus.
The CDC recommends that adults who have previously completed the routine polio vaccine series and are traveling to any destination listed may receive a single, lifetime booster dose of polio vaccine. Polio vaccination services are offered at most health clinics and travel pharmacies in the United States.
In Taiwan (Republic of China), Japanese Encephalitis (JE) has been a notifiable, mosquito-transmitted infectious disease since 1955.
As of July 2025, the Taiwan Centers for Disease Control (TCDC) confirmed six cases of JE in 2025.
Last year, Taiwan reported 25 JE cases.
Most JE cases are associated with activities in paddy fields, pig farms, pigeon farms, poultry farms, and ponds.
A recent study confirmed that JE remains a prevalent infectious disease in Taiwan. Between 2008 and 2020, 309 confirmed domestic JE patients and four imported cases.
This study confirmed that JE remains a prevalent infectious disease in Taiwan, with its epidemic gradually increasing in severity.
As of July 7, 2025, JE is a vaccine-preventable disease. In the United States, an FDA-approved JE vaccine is commercailly available at travel clinics and pharmacies. It is recommended for international travelers when visiting JE outbreak areas.
The Hawai‘i Department of Health (DOH) recently confirmed its ninth travel-related case of dengue in 2025.
As of the end of June 2025, the DOH reported eight dengue cases on Oʻahu and one case on Maui.
Several countries in the Pacific Region are reporting an increase in mosquito-transmitted dengue virus cases, including Fiji, French Polynesia, Tonga, and the Republic of the Philippines.
According to the World Health Organization, dengue is a grade 3 emergency, with an estimated 4 billion people at risk globally.
The U.S. Centers for Disease Control and Prevention (CDC) reissued a Global Travel Health Notice on June 18, 2025, regarding dengue outbreaks in the Asia/Pacific region, including India, Singapore, Thailand, the Philippines, Malaysia, and Myanmar.
CDC reported on July 3, 2025, that 2,248 travel-related Dengue cases and two local cases in Miami, Florida, were reported in 41 jurisdictions this year.
While the CDC currently authorizes the first-generation dengue vaccine for use in Puerto Rico, where dengue has become endemic, numerous countries enable access to a second-generation vaccine in 2025. Additionally, innovative dengue vaccine candidates are making progress in late-stage clinical trials.
The Republic of Peru frequently declares regional states of emergency, particularly near border areas.
To highlight these high-risk zones, the Canadian government updated its travel advisory for Peru on July 4, 2025, informing travelers to exercise a high degree of caution in Peru due to civial unrest that may occur across the country.
These areas include:
Huallaga and Tocache provinces in the department of San Martín,
the Upper Huallaga and Ene river valleys in the departments of Huánuco and San Martín,
Padre Abad province in the department of Ucayali,
Huacaybamba, Humalíes, Leoncio Prado, and Marañón provinces in the department of Huánuco,
Concepción and Satipo provinces in the department of Junín,
Tayacaja province in the department of Huancavelica,
the districts of Abancay, Andahuaylas, and Chincheros in the department of Apurímac,
Huanta and La Mar provinces, in the department of Ayacucho,
Valley of Apurimac, Ene, and Mantaro rivers (VRAEM).
Previously, the U.S. Department of State reissued its Level 2: Exercise Increased Caution Travel Advisory for this South American country on May 16, 2025.
From a health risk perspective, the U.S. CDC includes Peru in Travel Health Advisories for measles, Oropouche, and yellow fever.
The CDC recommends that visitors to Peru consider several routine and travel vaccines, such as typhoid and chikungunya, before traveling abroad in 2025.
These advisories are essential, as over 3 million international visitors traveled to Peru in 2024, representing a significant increase in activity compared to 2023. Many travelers visited Machu Picchu, located high up in the Andes Mountains.
The French Health Ministry has been reporting a significant number of locally acquired chikungunya cases in its Department in 2025. ARS Corsica states that the presence of the virus-carrying tiger mosquito is now well established in southern Corsica and throughout Europe.
As of July 2, 2025, a third locally acquired case of chikungunya has been detected in southern Corsica, in Porticcio (municipality of Grosseto-Prugna).
In late June 2025, ARS Corsica reported two cases of chikungunya from the same family, residing in Grossetto-Prugna.
On France's mainland, the Occitanie Regional Health Agency detected a locally transmitted case of Chikungunya in the Hérault Department on June 16, 2025. Another case was reported in La Crau (Var) on June 11, 2025.
Additionally, the Departments of Reunion and Mayotte in the southern India Ocean have been confronting chikungunya outbreaks over the last few months.
From a health protection perspective, chikungunya vaccines are now commercially available in France and the United States.
The U.S. CDC recommends that international travelers visiting areas with chikungunya outbreaks speak with a travel vaccine expert about immunization options.
