Frequently Asked Questions

Environmental Health

The USGS seeks to understand and minimize exposures to toxic agents and infectious disease agents in the environment.

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Image: USGS Scientist Set Mistnets for West Nile Virus Monitoring
West Nile Virus has been detected in all conterminous states of the U.S., the District of Columbia, and Puerto Rico. Alaska, Hawaii, and Guam have no reported cases of West Nile virus in humans or animals. Distribution maps are available from the USGS and the Centers for Disease Control.
three neotropical birds (Left to right: Magnolia warbler, Wilson's warbler, Canada warbler - all males) that were cought in mist
West Nile Virus is most often spread to humans from the bite of an infected mosquito. However, it’s always a good idea to follow basic hygienic procedures. Birdbaths and feeders should be washed or disinfected regularly. Wash your hands with soap and water after touching the baths/feeders. Here is a brochure on best practices for coping with...
Dr. Prosser taking samples
Signs of infection in wildlife, like in humans, can range from no symptoms to severe symptoms of neurologic illness. Commonly reported signs in animals include weakness, stumbling, trembling, head tremors, inability to fly/walk, and a lack of awareness that allows them to be easily approached and handled. These symptoms, however, can also have...
Mosquito takes a bloodmeal from an apapane
This is an issue of great concern, as these populations are already struggling to survive in the current environment. If some of these species are more vulnerable to fatal WNV infection, WNV may ultimately lead to their extinction or significantly set back the progress of the recovery programs.
Dr. Diann J. Prosser examining a ruddy shelduck
Under normal conditions, humans are unlikely to be infected with West Nile Virus by handling a sick or dead animal. However, there are a number of other infections that could potentially result from handling an animal. To protect yourself from exposure to any illness, you should wear gloves or put a plastic bag over your hand before touching the...
Free-roaming cat and an orange-crowned warbler
Experimentally, it was found that this might be possible. However, there has been no evidence to indicate that West Nile Virus can be naturally transmitted to cats or dogs that carry or consume infected animals. Dogs and cats can be infected with West Nile Virus through the bite of a mosquito, so minimizing their exposure to mosquitoes is...
Image: Northern Pintail Duck
Some game birds have tested positive for West Nile Virus (WNV). However, there is no evidence of human infection by consumption of properly cooked infected game. Hunters are likely at higher risk of infection by mosquito exposure, particularly in wetland environments. Protective measures should be taken to prevent mosquito exposure while hunting....
A Kaua‘i Amakihi on koli‘i
West Nile Virus (WNV) has been detected in at least 48 species of mosquitoes, over 320 species of birds, at least 2 species of reptiles, and more than 25 mammalian species, including horses and humans. Birds are the natural host and reservoir of WNV. Although other animals are susceptible to WNV infection, only birds develop a high enough virus...
Brandt Meixell is holding two pintail ducks that he just retrieved from a net pen
State and federal government experts continue to evaluate how Highly Pathogenic Avian Influenza (HPAI) viruses can spread and impact wild and domestic birds. The global spread of HPAI subtype H5N8 has been driven in large part by migratory waterfowl. Knowledge about migratory patterns and intercontinental associations of waterfowl, as well as...
Whooping Crane, Grus americana, given the Eastern Equine Encephalitis vaccination
At this time, there is not a West Nile Virus vaccine approved for use in birds. The Centers for Disease Control and Prevention, in collaboration with several organizations and laboratories, is developing and testing vaccines for use in birds. Many zoos and wildlife centers have been using the Fort Dodge horse vaccine (West Nile-Innovator®) in...
Female scientist looking through microscope.
To learn more about the impacts of avian influenza on wild birds and the role wild birds may play in the spread of the virus, experts from government agencies have gathered samples from hundreds of thousands of live-captured, apparently healthy wild birds; hunter-harvested birds; and dead wild birds of all species. Testing methods include analyses...
Emperor Geese, central coast, Yukon Delta National Wildlife Refuge
While rare, human infections with avian influenza viruses have occurred. The Centers for Disease Control and Prevention considers the risk to the general public from HPAI H5 infections in wild birds, backyard flocks, and commercial poultry, to be low. To date, no humans or other mammals have shown signs of disease from the HPAI viruses found in...