The World Health Organization (WHO) said in a new risk assessment today that two recent human H5N1 avian flu cases involved the older 126.96.36.199c clade, not the one circulating widely in poultry in multiple world regions.
The two cases were reported in January and are part of an uptick in human H5N1 infections in Cambodia, following a nearly decade-long absence. The WHO also added new details about the infections and investigations. One of the cases was found as part of severe acute respiratory illness surveillance, and the other was identified by a doctor at a site that wasn't in a surveillance network.
Exposure to sick birds preceded both infections
Both patients had been exposed to sick birds before their symptoms began. Backyard chickens were found dead around the 3-year-old child's house, and the 69-year-old patient had raised domestic birds and fighting roosters, of which three chickens were positive for H5N1.
Monitoring and testing of the two patients' contacts yielded no other flu cases, except for an unrelated influenza B infection in one of the older patient's contacts.
Risk remains where poultry are infected
The two new cases put the number of H5N1 in Cambodia at 8 since 2023. Since the first infections were reported in 2003, the country has reported 64 cases, 41 of them fatal. The WHO said the risk to the general human population from H5N1 viruses remains low and that sporadic human infections will likely continue, especially in rural Cambodia and other countries where the virus is endemic in poultry.
The agency urged people to avoid high-risk environments such as live-animal markets and to quickly report unexpected animal deaths to veterinary officials. In countries where avian flu is known to circulate, the WHO recommends wearing respiratory protection and barriers while slaughtering or handling slaughtered poultry.