Environmental and Demographic Determinants of Avian Influenza Viruses in Waterfowl across the Contiguous United States

Abstract

Outbreaks of avian influenza in North American poultry have been linked to wild waterfowl. A first step towards understanding where and when avian influenza viruses might emerge from North American waterfowl is to identify environmental and demographic determinants of infection in their populations. Laboratory studies indicate water temperature as one determinant of environmental viral persistence and we explored this hypothesis at the landscape scale. We also hypothesized that the interval apparent prevalence in ducks within a local watershed during the overwintering season would influence infection probabilities during the following breeding season within the same local watershed. Using avian influenza virus surveillance data collected from 19,965 wild waterfowl across the contiguous United States between October 2006 and September 2009 We fit Logistic regression models relating the infection status of individual birds sampled on their breeding grounds to demographic characteristics, temperature, and interval apparent prevalence during the preceding overwintering season at the local watershed scale. We found strong support for sex, age, and species differences in the probability an individual duck tested positive for avian influenza virus. In addition, we found that for every seven days the local minimum temperature fell below zero, the chance an individual would test positive for avian influenza virus increased by 5.9 percent. We also found a twelve percent increase in the chance an individual would test positive during the breeding season for every ten percent increase in the interval apparent prevalence during the prior overwintering season. These results suggest that viral deposition in water and sub-freezing temperatures during the overwintering season may act as determinants of individual level infection risk during the subsequent breeding season. Our findings have implications for future surveillance activities in waterfowl and domestic poultry populations. Further study is needed to identify how these drivers might interact with other host-specific infection determinants, such as species phylogeny, immunological status, and behavioral characteristics.

Surveillance for Highly Pathogenic Avian Influenza in Wild Turkeys (Meleagris gallopavo) of Minnesota, USA during 2015 Outbreaks in Domestic Poultry

“…This analysis revealed geographic regions where influenza virus in sampled waterfowl was higher than expected [2]. A majority of these influenza clusters occur in more northern latitudes, a finding supported by previous studies related to location of major waterfowl breeding grounds and additional research on the environmental persistence of influenzas at cold temperatures [3]. These results offer an important data stream to inform high priority areas for wild bird avian influenza surveillance.…”

“…Temperature is associated with waterfowl migration and influences avian influenza persistence in the environment. There is a well-documented pattern of reduced avian influenza prevalence in waterfowl at southern latitudes, especially during the breeding season [3]. This is largely attributed to viral degradation at higher temperatures [6].…”

Trade-offs between and within scales: environmental persistence and within-host fitness of avian influenza viruses

“…While the proximity of many birds in large flocks can lead to rapid transmission and large-scale outbreaks, it has recently been appreciated that prolonged persistence of influenza virus in the aquatic environment is possible [10][11][12][13]. This might lead to additional, indirect chains of transmission [14][15][16][17][18].…”

Spread and Persistence of Influenza A Viruses in Waterfowl Hosts in the North American Mississippi Migratory Flyway

“…This study offers support for the AIV spread by migratory wild birds evident in the dispersal of AIV segment genetic diversity within the migratory flyway over short periods. However, the apparently stochastic nature by which AIV lineages disperse, in addition to the selective pressures limiting most dispersal events, makes it difficult to determine the ecological factors influencing AIV gene flow in wild birds within the MMF (73). Ultimately, surveillance efforts in wild birds should be conducted with the goal of capturing AIV diversity, both antigenic and genetic, to prevent and prepare for pandemic threats and potential spillover to domestic animals (7).…”