20.06.2014

Nature Communications (2014)

Two epidemic waves of an avian influenza A (H7N9) virus have so far affected China. Most human cases have been attributable to poultry exposure at live-poultry markets, where most positive isolates were sampled. Based on a retrospective study of the spatial distribution of markets infected by H7N9 in 2013 and 2014, an international researcher team developed a spatial model that can accurately predict the risk of market H7N9 infection in China, and can be extrapolated to Asia. Local live-poultry market density is found to be the most important predictor variable of H7N9 infection risk at the market level. Other predictor variables of H7N9 infection risk include the population densities of chickens reared in extensive and intensive systems, water bodies, accessibility to major cities, human and domestic duck population density and rice land cover. The areas predicted to be most suitable for new H7N9 market infection include specific urban areas of China where the disease has not yet occurred, an extensive area in Bengal, the river deltas of Vietnam, and parts of Indonesia and Philippines. These maps aim to facilitate evidence-based prioritization of surveillance in the region. They should help the early detection of new incursions, early response and active containment, minimizing impacts to agricultural livelihoods and reducing risk to human health.