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The WHO today published its Multi-country outbreak of mpox External situation report #57.
The World Health Organization (WHO) stated on August 28, 2025, that all monkeypox virus (MPXV) clades continue to circulate in several countries. When mpox outbreaks are not rapidly contained and human-to-human transmission is not interrupted, they continue to pose a risk of sustained community transmission.
In July 2025, 47 countries in five (out of six) WHO regions reported a total of 3,924 confirmed cases, including 30 deaths (case fatality ratio 0.8%).
The South-East Asian and Western Pacific regions reported an increase in cases in July 2025, while the African Region, European Region, and the Region of the Americas reported a decrease.
To alert international travelers to this serious health risk, the WHO Director-General has extended the standing recommendations for mpox issued to States Parties until August 20, 2026, to prevent further spread or reduce the international spread of mpox, as well as its impact on health.
The WHO and the U.S. CDC recommend mpox vaccination for those with the highest risk profile.
In June, the Institut Pasteur confirmed an unprecedented situation this summer, with locally acquired, mosquito-transmitted disease accelerating in France.
As of August 26, 2025, Public Health France reported 37 episodes of indigenous vector transmission have been identified in mainland France:
There have been 30 episodes of chikungunya, resulting in a total of 228 cases.
And seven separate episodes of dengue fever, totaling 15 cases.
They are located in the Provence-Alpes-Côte d'Azur, Corsica, Occitanie, Auvergne-Rhône-Alpes regions, already affected in previous years, and for the first time in Grand Est, Nouvelle-Aquitaine, and Bourgogne-Franche-Comté.
Furthermore, 15 human cases of vector-borne West Nile virus infection have been identified in five departments of mainland France. The affected regions are PACA, Occitanie, and, for the first time, Île-de-France.
Additionally, travel-related cases continue to be confirmed in 2025.
France has reported 946 imported cases of chikungunya, 825 imported cases of dengue fever, and seven imported cases of Zika.
When visiting France this year, the U.S. CDC offers various travel vaccine recommendations for anyone visiting disease outbreak areas. Currently, there are no vaccines available for West Nile or Zika viruses.
However, chikungunya vaccination services are offered in both France and the USA.
In light of the resurgence of pertussis across several countries in the region and the emergence and spread of antibiotic-resistant strains, the Pan American Health Organization (PAHO) reiterated the importance of strengthening vaccination and surveillance systems.
Known as Whooping cough, pertussis, is a very contagious respiratory illness that has resurged in the Americas. While 4,139 cases were reported in 2023, the number soared to 43,751 in 2024.
In the United States, preliminary data show that more than six times as many cases were reported in 2024 compared to 2023.
In the first seven months of 2025, nine countries, including Brazil, Mexico, Peru, and the U.S., reported over 18,595 cases and 128 deaths.
The PAHO states that the resurgence is linked to declining vaccination rates and emphasizes the need for strengthened, standardized surveillance.
Regional coverage for the first and third vaccine doses dropped to historic lows of 87% and 81% in 2021, respectively.
By 2023, a partial recovery was observed (90% and 88%), but these rates remain below the 95% recommended by PAHO, with significant disparities within countries.
Pilar Ramón-Pardo, head of PAHO's Special Program on Antimicrobial Resistance, commented in a media release on August 26, 2025, "We still have time to contain this issue, but we must act now: increase vaccination coverage, strengthen early detection, and enhance our outbreak response capacity."
When visiting countries such as Brazil, the U.S. CDC recommends travelers be protected against pertussis. Specifically, vaccination is essential from pregnant women and infants visiting outbreak areas.
Various pertussis vaccines are offered at clinics and pharmacies in August 2025.
While the U.S. Centers for Disease Control and Prevention (CDC) states that Dengue is a year-round risk in many parts of the world, some countries are reporting an increase in cases of this mosquito-borne disease this year.
Since the beginning of 2025, over 4 million Dengue cases and over 2,500 dengue-related deaths have been reported from 101 countries/territories.
On August 21, 2025, the CDC updated its Travel Health Advisory, identifying a higher-than-expected number of dengue cases among U.S. travelers returning from these 18 countries.
Should you visit these areas, the CDC says to prevent mosquito bites, use an EPA-registered insect repellent, wear long-sleeved shirts and long pants when outdoors, and sleep in an air-conditioned room or a room with window screens.
The disease can take up to two weeks to develop, with illness generally lasting less than a week. Symptoms of Dengue include fever, headache, nausea, vomiting, rash, muscle and joint pain, and minor bleeding.
Currently, U.S. FDA-approved Dengue vaccines are only available in Puerto Rico, where Dengue has become endemic.
The second-generation vaccination is available in various countries, but not in the USA.
Chikungunya virus (CHIKV) disease is currently not classified as a notifiable disease in China. However, both Aedes albopictus and Aedes aegypti mosquitoes, which transmit this serious virus to people, are known to be present in Guangdong Province, a southeastern Chinese province.
According to the European Centre for Disease Prevention and Control (ECDC), as of August 16, 2025, 9,933 CHIKV disease cases have been reported in Guangdong Province since the outbreak began in July 2025.
Last week, the Guangdong Provincial CDC reported 830 new CHIKV cases, primarily from Foshan (644) and Guangzhou (85).
Since international travelers frequently visit these Chinese cities, the ECDC has assessed the risk to visitors.
According to International Air Transport Association data from July and August 2024, more than 60,000 travelers arrived in the mainland EU/EEA from the affected region via the two major international airports situated near the epicenter of the outbreak.
The positive news is that Chinese public health authorities have implemented stringent vector control measures aimed at reducing mosquito populations.
Furthermore, given the typically self-limiting nature of the disease and the limited severity of clinical outcomes in most cases, the overall impact is considered low.
Therefore, based on current epidemiological data and control measures in place, the risk of chikungunya virus infection in travellers returning from the affected areas of Guangdong province to the EU/EEA is assessed as low.
However, the importation of the virus by travelers returning from China may result in additional local transmissions, as seen in France and Italy.
To alert travelers, on August 26, 2025, the U.S. CDC updated its Travel Health Advisory, stating, 'if you are pregnant, reconsider travel to the affected areas, particularly if you are close to delivering your baby.'
Additionally, vaccination is recommended for travelers who are visiting an area with a chikungunya outbreak.
During the first half of the 20th century, there were three island–wide dengue fever outbreaks in the Republic of China's Taiwan. In 2015, Taiwan battled one of the most severe dengue outbreaks in history with over 43,000 dengue cases, including 228 related fatalities.
Based on new data from the Taiwan Centers for Disease Control (TCDC), four confirmed cases of dengue type 2 have been reported in Gushan District, Kaohsiung City. These individuals are receiving treatment at a local hospital.
According to CNA reporting on August 25, 2025, positive breeding sources were detected at the cases' residences. Additionally, the confirmed cases had no recent record of travel abroad. The TCDC judged that all cases were local and that it was a community cluster event.
The TCDC reminds everyone that it is currently dengue fever season, and recent rainfall has increased the population of mosquitoes that carry the virus.
To alert international travelers of this global health risk, the U.S. CDC reissued its Level 1 Travel Health Advisory on August 21, 2025. While the CDC listed various countries, it did not include Taiwan.
From a disease prevention perspective, several countries in the Asia-Pacific region offer a second-generation dengue vaccine that has been found effective against type 2 virus infections.
The mosquito-transmitted West Nile virus was first detected in New York's five boroughs more than 25 years ago, with about 31 people infected in recent years.
According to the New York Health Department press release on August 22, 2025, West Nile virus disease has been reported in two New Yorkers, both residents of Queens.
One individual was diagnosed with West Nile fever, was briefly hospitalized, and has since been discharged.
The second individual was diagnosed with West Nile neuroinvasive disease and is currently hospitalized with encephalitis, an infection in the brain.
In addition, the virus was detected in blood donations from two individuals, one a resident of Brooklyn, the other of Staten Island.
Recent reports of two more individuals (both from Brooklyn) with possible West Nile virus disease are under investigation.
While most patients infected with West Nile virus disease go on to fully recover, some continue to have health problems months after infection. In addition, about 1 in 150 people, especially those 55 years and older or with a weakened immune system, can develop a serious and potentially fatal illness of the brain and spinal cord called West Nile neuroinvasive disease, leading to changes in mental status and muscle weakness requiring hospitalization, according to the Health Department.
"West Nile virus can cause serious illness, especially among people over 55 and with weakened immune systems," said Acting Health Commissioner Dr. Michelle Morse in the press release.
"The Health Department says ... use an EPA-registered repellent and wear long sleeve shirts and pants — especially at dawn and dusk when mosquitoes that transmit the virus are active."
And, "Eliminate standing water so mosquitoes can't breed, and make sure you have intact screens on your doors and windows. The virus has been detected in mosquitoes across the city — visit the online map."
The Health Department stated ten adulticiding spray operations, three aerial larvicidings, two rounds of catch basin larviciding, and 1,104 ground-based larvicidings have been completed to date.
Across the United States, the U.S. CDC reports that 33 states have confirmed over 320 WNV cases in 2025.
And in Europe, as of August 20, 2025, nine countries have reported human cases of WNV: Albania, Bulgaria, France, Greece, Hungary, Italy, Romania, Serbia, and Spain.
From a prevention perspective, there are no West Nile virus vaccines available in 2025.
