Estimating Dynamic Risk Factors for Pathogen Transmission Using Community-Level Bird Census Data at the Wildlife/Domestic Interface

The ecology of host species is crucial for understanding the mechanisms of pathogen transmission and spread in complex multi-host systems. In this article, we use detailed observations of the host community to develop and apply a new approach to mapping temporal variation in risk for avian influenza. Working in an extensive wetland system near Harare, Zimbabwe, we use the overlap in space and time of highly variable bird communities, combined with ecological risk factors, to assess the risk of Avian Influenza viruses (AIV) maintenance and transmission between bird populations. The estimated introduction and maintenance risks associated with waterfowl populations at a given time are then multiplied by the level of interactions with neighboring domestic production systems during the same period. This approach is used to develop hypotheses for the dynamics of the introduction and circulation of AIV strains in waterfowl populations and as a way of understanding the potential role of "bridge" species at the wild/domestic interface. The novel approach presented here offers a potentially useful way to explore AIV risk, identify which wild bird species may be acting as reservoirs or vectors of pathogens at a local scale, and improve local surveillance.