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Animal and Plant Health Inspection Service
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Avian Health

Wild bird surveillance mallard in MT
Wildlife Services’ National Wildlife Disease Program (NWDP) collects samples from wild birds for disease surveillance. Surveillance helps APHIS better understand and track the presence of avian influenza and other pathogens of concern along migratory bird pathways.

The NWDP and its partners lead the largest national avian influenza surveillance effort for U.S. wild bird populations. Since 2006, they collected 500,000 samples from wild birds, serving as an early warning system for highly pathogenic influenza viruses. Many of these samples come from live trapping and opportunistic collection from hunter harvest. The program also collects samples for other avian pathogens that have a potential impact on domestic poultry, human health, or other wild bird species. The diseases monitored as part of this avian health project include avian influenza, avian paramyxovirus serotype-1, and arboviruses. The NWDP learns more about the ecology of these diseases and the risks posed to humans, domestic poultry, and wildlife by monitoring these pathogens.

Avian Influenza

WS disease biologist Todd Felix releasing mallard in CO

Low pathogenicity avian influenza is common in wild birds around the world. In most cases, it causes few or no signs of infection. However, some strains can become highly pathogenic in domestic poultry. Highly pathogenic avian influenza is extremely contagious and deadly to domestic poultry. If found in the United States, the appropriate management action is to quickly eradicate the disease to protect our Nation’s flocks and economy. Wild bird surveillance helps APHIS to better understand and track the presence of avian influenza variants of concern along migratory wild bird pathways. It also serves as an early warning system, ensuring APHIS, and the poultry industry enhance biosecurity measures and rapidly respond to reduce the risk of disease spread. For more information, please see:

Avian Paramyxovirus serotype-1 

Newcastle disease (ND) is a contagious viral disease of birds. ND is caused by virulent avian paramyxovirus serotype 1 (APMV-1). More than 230 bird species are susceptible to avian paramyxoviruses (APMV), but most infected birds do not show symptoms. In wild birds, the effects vary depending on the bird species and the severity of the APMV strain. ND is usually suspected when large die-offs of cormorants, gulls, or pelicans are detected in the upper Midwest or northeast regions of the United States.

Severity of APMV-1 is measured by its ability to cause disease in chickens and is subsequently categorized as a high or low pathogenic virus. Virulent Newcastle disease virus (NDV) refers only to virus strains of high pathogenicity. The poultry industry is concerned with NDV because it causes illness, death, and reduced egg production resulting in severe economic losses. While rare in the United States, NDV is occasionally introduced by illegal trafficking of exotic birds.


Eastern equine encephalitis virus (EEEV), St. Louis encephalitis virus (SLEV), and LaCrosse virus (LACV) are mosquito-borne diseases causing severe symptoms in humans, like neurological disease or death.

Turlock virus (TURV) is another common type of arbovirus but infects domestic birds instead of humans or domestic animals.


Salmonella spp. are common bacteria causing infection in birds, other animals, and people. Salmonella spp. infection is a continuous problem for the poultry industry and leads to significant morbidity and mortality in domestic flocks. Eggs or meat contaminated with Salmonella spp. routinely cause outbreaks in people and represent a public health risk. Infection is common in wild birds, especially in areas where large numbers of birds gather.

NWDP Coordinator:

Julie Lenoch, DVM
(970) 266-6056
USDA/APHIS/WS4101 Laporte Ave
Fort Collins, CO 80521
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