# Avian Influenza

## Science Center Objects

Avian influenza outbreaks can result in significant economic loss, as in 2014-2015 when the Congressional Research Service estimated losses of $3.3 billion dollars from the death and culling of domestic poultry due to an outbreak of this disease. Patuxent’s avian influenza research seeks to answer such questions as “How far can a bird carrying this virus travel?” and “What influences the transmission of this disease between wild birds and poultry?” American black duck (Anas rubripes) (Public domain.) Spatiotemporal Exploratory Models: Deriving Spatial Waterfowl Inputs for Disease Risk Modeling Disease risk modeling can be an important tool for identifying areas of high transmission risk within and between animal populations, allowing for strategic allocation of limited resources for disease surveillance and prevention. Acquiring a spatial understanding of the distributions of high risk populations is a critical first step in developing predictive disease transmission models. One such disease is highly pathogenic avian influenza, outbreaks of which have caused concern for both domestic and wild populations in the United States. Little is known about the way avian influenza can impact ruddy ducks, an issue this study seeks to remedy. Credit: Glenn Bartley/VIREO (Credit: Tom Koerner, US Fish and Wildlife Service. Public domain.) Highly Pathogenic Avian Influenza Seaduck Challenge Study The susceptibility and pathogenesis of highly pathogenic avian influenza virus (HPAI) has not been characterized in numerous duck species, especially diving ducks (genera Melanitta, Aythya, and Oxyura), some of which migrate across the continental US. The few studies available (on Tufted duck, Aythya fuligula) suggest that they may shed high amounts of virus, but it is unclear whether they have the capacity to spread HPAI long distances. A depiction of North America’s major waterfowl flyways (from left to right: Pacific, Central, Mississippi, and Atlantic; Credit NWF) Avian Influenza Surveillance in Waterfowl in the Atlantic Flyway In December of 2014, a novel strain of highly pathogenic avian influenza (HPAI) caused an outbreak in poultry on the West coast of the United States. From there, the virus progressed steadily eastward, causing$3.3 billion in economic losses in addition to 50 million chickens or turkeys dying or being depopulated. While the primary mode of spread appears to be via the poultry system, wild birds have been detected with H5N8 asymptomatic infection, indicating the potential for virus spread via wild populations. The species involved and the extent of contribution of virus spread, however, are not known. As of June 2015, the new strains of HPAI have been detected in 3 of the 4 migratory flyways, with no positives yet in the Atlantic flyway; however little sampling has been conducted since the onset of the current HPAI situation.

Mallard (Anas platyrhynchos) post-sampling and ready for release (Public domain.)

Pathogens in the Aquatic Environment – Waterfowl, Avian Influenza

Changes in aquatic ecosystems related to climate change phenomena or other anthropogenically based environmental stressors have significant impact on the dynamics of the host-pathogen-environment relationship, often with surprising results. Therefore, biosurveillance of the aquatic environment for pathogens of significance to aquatic and terrestrial wildlife, as well as to domestic animals and humans, is a focus area of increasing importance in ecosystems science. The study of avian influenza viruses in the aquatic environment is a suitable model for such biosurveillance-based investigations as the pathogen is both persistent in many aquatic reservoirs and highly significant to wildlife, poultry, and human health.

Using satellite telemetry to study wild bird movements in relation to HPAI. (Public domain.)

USGS Wild Bird Avian Influenza Program – Studies from Endemic Regions of Eurasia

Following outbreaks of highly pathogenic avian influenza (HPAI) in Eurasia, many researchers have attempted to determine how this virus spreads across the landscape. Unfortunately, prior to this work, most studies on HPAI movements were based on virology data alone, and no information on host ecology. Beginning in 2007, USGS Patuxent Wildlife Research Center (PWRC) and Western Ecological Research Center (WERC) developed a Wild Bird Avian Influenza Program to improve the scientific understanding of the role wild bird’s play in the circulation of highly pathogenic avian influenza.

These domestic ducks have been fit with GPS transmitters to track their movements through the market chain. (Public domain.)

Tracking Domestic Ducks through the Market Chain in China via Telemetry

Highly pathogenic avian influenza viruses (HPAI) of certain subtypes primarily infect poultry, causing disease outbreaks and negative socio-economic impacts on poultry farming depending on the characteristics of biosecurity and the virus strain. HPAI viruses seem to be adapted to artificial ecosystems including poultry farming, free-ranging duck production, and live bird markets, rather than to natural ecosystems. Although detailed knowledge of the agro-ecological conditions associated with HPAI is still limited, the live bird trade is currently known to be a major pathway for its spread. The Asia-Pacific region has been regarded as an epicenter of new emerging infectious diseases due to the high density of human populations, and the increasing agriculture and livestock production with varying biosecurity levels and integration with human living space.