Evidence Links Live Poultry Markets to Human H5N1 Infection

Shanghai Wet Market (Image from Flickr, by Augapfel)

China’s wet markets (live food markets) have long been suspected of being reservoirs for the deadly H5N1 avian flu. The scientific evidence supporting this hypothesis has just been published in the December 2011 Journal of Virology.

Scientists sequenced the H5N1 virus from live bird markets in China and were able to match it to sequences of H5N1 found in patients who had recently visited the live bird markets. They picked up 69 environmental samples from cages, floors and ditches at six wet markets during the 2008-2009 flu season, finding H5N1 at four of the markets. The genetic sequence of the environmental samples had a greater than 99% correspondence to human isolates, according to the Medical Express blog.

These findings are important because they support improving veterinary monitoring and control of the wet markets and quicker culling when infections are identified. H5N1 is still primarily passed to directly humans through infected animals and has a 60% mortality rate among infected humans. However, because the wet markets facilitate the comingling of numerous different species, including fowl and pigs, they are a likely breeding ground for a deadly genetic reassortment that could make the virus easily transmissible between people.