The market for live poultry might be fuelling the spread of avian flu viruses in China, according to an analysis of viral genomes and models of the poultry trade.

Some influenza viruses that infect birds can also infect people: the H5N1 virus, for example, which has an estimated fatality rate of 50–60% in humans. Huaiyu Tian at Beijing Normal University and his colleagues analysed the genome sequences of viruses collected from public databases. This allowed the researchers to trace the spread of H5N1 and two other avian flu virus strains in poultry in Chinese provinces.

The team divided China into five regions, each composed of communities that trade chickens and other poultry more extensively with each other than with communities in other regions. The researchers found that all three flu viruses were disseminated faster within a live-poultry-trading region than between such regions. According to another analysis, the flow of viral genes around the country mapped to the structure of the live-poultry-trade network.

Both analyses pinpointed four geographical hubs that might be particularly important to flu virus transmission between the five regions.