A Case of Avian Influenza A

This article describes asymptomatic infection with avian influenza A(H5N1) in a British individual who kept a flock of about 125 ducks at their home. Following the deaths of several ducks and signs of clinical illness in others, veterinary and health authorities tested a sampling of ducks (with 19 of 20 testing positive) and the exposed owner. This was the first avian influenza A(H5N1) infection in humans identified in Europe. Contact tracing identified 11 individuals who were actively monitored for 10 days, instructed to wear personal protective equipment during interactions with the index case, and offered antivirals and asymptomatic testing. One individual who had close contact with the index case received post-exposure antiviral prophylaxis. No other individuals were infected either as primary cases or as a result of human-to-human transmission. The authors discuss the importance of asymptomatic testing of exposed humans when avian influenza prevalence is high to detect potential transmission from birds to humans, facilitate case and situation management, and refine public health risk assessments.