Geneva: Six deaths from avian influenza A(H5N1) in Cambodia this year have raised alarm, with the country reporting 11 laboratory-confirmed human infections to the World Health Organization (WHO) between January 1 and July 1, 2025, through Cambodia’s International Health Regulations (IHR) National Focal Point. Seven cases in June alone mark a sharp monthly increase, heightening concerns about the virus’s spread.
First detected in Cambodia in December 2003 in wild birds, A(H5N1) has caused 83 human infections in the country, with 49 deaths, for a case fatality ratio of 59%. After no human cases from 2014 to 2022, the virus re-emerged in February 2023, leading to 27 cases across eight provinces—Kampong Cham, Kampong Speu, Kampot, Kratie, Prey Veng, Svay Rieng, Siem Reap, and Takeo—with 12 deaths and a case fatality ratio of 44%. Seventeen of these cases were in children under 18.
The 2025 cases, with six deaths for a case fatality ratio of 54%, were reported in Siem Reap (four cases), Takeo (two cases), and one each in Kampong Cham, Kampong Speu, Kratie, Prey Veng, and Svay Rieng. Males made up 63% of cases, with three in children under five, two in those aged 5 to 18, and six in adults aged 18 to 65. All cases involved handling or culling sick poultry, often in backyard settings, with the virus identified as clade 2.3.2.1e (previously 2.3.2.1c), where sequences were available. Globally, from 2003 to July 1, 2025, the WHO has recorded 986 A(H5N1) cases across 25 countries, with 473 deaths, for a 48% case fatality ratio, nearly all linked to contact with infected birds or contaminated environments.
Avian influenza A(H5N1) spreads mainly among wild birds, poultry, and some mammals but can infect humans through direct contact with sick animals or contaminated areas, as seen in Cambodia’s cases. Symptoms range from mild, like a cold, to severe, including breathing problems, stomach issues, or rare brain conditions like encephalitis or encephalopathy. Some people show no symptoms despite exposure. Lab tests, often using RT-PCR, confirm diagnosis, and early treatment with antiviral drugs like oseltamivir or zanamivir, given within 48 hours of symptoms, can help recovery.
Cambodia’s Ministry of Health has deployed national and local rapid response teams, working with the Ministry of Environment and the Ministry of Agriculture, Forestry, and Fisheries, to investigate the outbreak. They are tracing transmission sources, increasing surveillance, detecting suspected cases, preventing community spread, monitoring close contacts, and educating affected villages. The General Directorate of Animal Health and Production and local teams are tackling poultry outbreaks by disinfecting areas, restricting animal movement, and raising awareness about poultry diseases.
WHO has assessed the public health risk as low for the general population but low to moderate for those handling poultry, like farm workers, depending on safety measures. Human-to-human transmission is unlikely based on current data, but more cases are expected due to the virus’s spread in animals. WHO is analysing the virus’s behaviour, studying its genetics, and updating risk assessments. Regular flu vaccines don’t protect against A(H5N1), but some countries have specific vaccines, and WHO updates its list of candidate vaccine viruses twice yearly, with extra updates as needed.
WHO has advised avoiding contact with sick or dead animals, live animal markets, or surfaces with poultry droppings, and cooking eggs and poultry thoroughly. Handling sick poultry should be avoided, and good hand hygiene, using soap or alcohol-based sanitisers, is essential. Anyone feeling sick after animal contact should seek medical care and report the exposure. No travel screenings or restrictions are recommended. For suspected cases, officials should investigate animal exposure, trace contacts, and send samples to WHO centres for testing. Under the IHR, countries must report new influenza subtype cases to the WHO, even if the person isn’t sick. Cambodia’s outbreak remains under close watch as authorities work to contain it.
– global bihari bureau
