Identifying patterns of influenza A genotypes in wild birds

Wild bird reservoirs of influenza A contribute to the overall genetic diversity of influenza, an increased range of endemic areas, as well as, transmission methods not commonly seen in human infections. These additions to influenza transmission increase the threat posed to human populations. Therefore, understanding the patterns of transmission of influenza A subtypes in avian hosts, as well as the environmental variables associated with transmission, is paramount to creating effective surveillance programs and forecasting potential areas of high genetic changes. Using a dataset of ~151,000 birds sample for avian influenza in the US and Canada from 1986-2017, we explore spatial patterns of influenza genotypes and model the environmental niches where certain types are found. Cluster analysis and niche modeling indicate overlap but also imperfect concordance between where each subtype of avian influenza was found and where each was predicted to circulate in wild bird populations. Overall, the Midwest and New England regions indicate higher risks of influenza A in wild birds across all flu types. In addition, the urban, wetland, and water land-cover types, as well as, low levels of human population density increase the likelihood of influenza presence in the avian populations. These results indicate that influenza transmission in wild birds is heavily affected by the activities of humans as well as the general characteristics of land cover types. Together, these results allow researchers to gain a better understanding of the spatial mechanisms of the broad scale patterns associated with influenza and the areas of particular risk associated with subtypes.