A sample from a Hong Kong wet market tested positive for H9 bird flu, days after a two-year-old boy who visited the market was diagnosed with a mild strain of the virus. Authorities assess the risk of a widespread outbreak as low.
The detection of H9 bird flu in a Hong Kong wet market and a human case highlights the ongoing risk of zoonotic disease transmission and the importance of public health surveillance, particularly in areas with live poultry markets.
A sample collected from a wet market in Hong Kong has tested positive for the H9 bird flu strain, days after a two-year-old boy who visited the venue was confirmed to have contracted a mild form of the infectious disease. The Centre for Health Protection (CHP) stated on Monday that the risk of a widespread outbreak was low.
The boy, a resident of Sha Tin, developed a fever and mild diarrhea on June 9. He was subsequently admitted to Prince of Wales Hospital and later transferred to Princess Margaret Hospital for treatment. His clinical specimen tested positive for the influenza A (H9) virus, with whole genome sequencing confirming it as the low-pathogenic H9N2 strain without significant genetic variations. The boy is currently in stable condition.
Preliminary investigations revealed the boy had no travel history, classifying the case as locally acquired. He does not attend school and spends most of his time at home. His household does not keep poultry, and he had not consumed undercooked poultry or knowingly come into contact with infected individuals. However, he visited Wo Che Market in Sha Tin on two occasions in early June with a family member, where he stayed at a fresh provision shop selling live chickens and touched the surroundings.
Seventeen environmental samples were collected from the boy's home, the market shop, and a nearby park. The market sample subsequently tested positive for H9 bird flu. The shop staff and the boy's six household contacts remain asymptomatic, and the latter are under medical surveillance.
The CHP advised parents to avoid taking young children to places where live poultry is sold, citing their weaker immune systems and potential for contact with contaminated environments. Globally, the WHO has recorded over 160 human H9 infections in the past decade, most presenting with mild illness and lacking sustained human-to-human transmission capabilities.