Meeting Abstract

S7-10  Wednesday, Jan. 6 14:30  Evidence of seasonality in a host-pathogen system: Influenza across the annual cycle of wild birds HILL, Nichola J.*; MA, Eric J.; MEIXELL, Brandt W.; LINDBERG, Mark; BOYCE, Walter M.; RUNSTADLER, Jonathan A.; Massachusetts Institute of Technology, Cambridge; Massachusetts Institute of Technology, Cambridge; U.S. Geological Survey, Alaska; University of Alaska, Fairbanks; University of California, Davis; Massachusetts Institute of Technology, Cambridge nhill@mit.edu http://runstadlerlab.mit.edu/people/nichola-hill

Influenza A Viruses (IAV) in nature must overcome shifting transmission barriers caused by the mobility of their primary host - migratory wild birds, which changes throughout the annual cycle. Using a phylogenetic network of viral sequences from North American wild birds, we demonstrate a shift from intraspecific to interspecific transmission that along with reassortment, allows IAV to achieve viral flow across successive seasons from summer to winter. This study supports a model of intense, short-chain transmission during summer breeding with minimal reassortment. As birds migrate from breeding sites to lower latitudes they become involved in transmission networks with greater connectivity to other bird species, with interspecies transmission of reassortant viruses peaking during the winter. We propose that switching transmission dynamics may be critical for the circulation of pathogens that infect mobile hosts in temperate climates with a strong seasonal signal. Understanding how transmission patterns vary seasonally may prove instructive for predicting how diseases spread after introduction into a migratory population and informing surveillance efforts.