Cluster of avian influenza in Cambodia
In February 2023, Cambodia reported a family cluster in Sithor Kandal district, Prey Veng province, with two people (a girl and her father) infected with avian influenza A(H5N1) virus. The 11-year-old girl died on 22 February, the father was asymptomatic, isolated at the referral hospital and has now been discharged.
During the epidemiological investigation, all samples taken from twelve contacts of the index case (the girl), apart from the father, tested negative for avian influenza A(H5N1). Deaths among backyard poultry and wild birds were previously reported in the village where the two cases originated, and the Ministry of Health confirmed that both cases were infected from birds. According to media quoting health authorities, an additional 29 contacts of these cases tested negative for the avian influenza virus.
Virus sequencing from the index case shows that this avian influenza A(H5N1) virus belongs to clade 2.3.2.1c, which is the viral clade circulating in poultry in Cambodia since 2014. This clade is different from the clade 2.3.4.4b that has been recently and widely circulating among birds in other parts of the world and in Europe, and which has also been detected in two human samples from asymptomatic poultry farm workers in Spain in 2022.
This is the first event of avian influenza A(H5N1) detected in humans in Cambodia since 2014. In the past, Cambodia reported 56 cases including 37 deaths between 2005 and 2014. As of today, there have been 58 cases of avian influenza A(H5N1) infection, including 38 deaths, reported in the country overall.
Risk for the EU/EEA
Sporadic human cases of different avian influenza A(H5Nx) subtypes have been previously reported globally and current epidemiological and virological evidence suggests that A(H5N1) viruses remain avian-like. Transmission to humans remains a rare event and no sustained transmission between humans has been observed.
Overall, the risk of zoonotic influenza transmission to the general public in EU/EEA countries is considered to be low. The risk to occupationally exposed groups such as cullers has been assessed as low to medium.
Direct contact with infected birds or a contaminated environment is the most likely source of infection. The use of personal protective equipment for people exposed to dead birds or their droppings is recommended to minimise the risk of infection. The recent severe cases in Asia and South America in individuals exposed to infected sick and dead backyard poultry underline the risk associated with unprotected contact with infected birds.
As of 27 February 2023, there have been 873 cases, including 458 deaths, of human infection with avian influenza A(H5N1) reported in 22 countries (Azerbaijan, Bangladesh, Cambodia, Canada, China, Djibouti, Ecuador, Egypt, Indonesia, India, Iraq, Laos, Myanmar, Nepal, Nigeria, Pakistan, Spain, Thailand, Türkiye, Vietnam, United Kingdom and United States). To date, no human-to-human transmission has been detected.
Reports from the Ministry of Health of Cambodia
ECDC podcast
Learn more about avian influenza and listen to ECDC on Air podcast episode with influenza expert Cornelia Adlhoch:
ECDC podcast: Episode 15 - Cornelia Adlhoch - Preparing For the Flu Season
ECDC influenza expert Cornelia Adlhoch explains the basic facts on avian influenza, including how it spreads, the threat to humans, and the ‘cathedral of silence’ that farmers can experience when walking into an infected chicken coop.
