[ODFW-News] ODFW monitoring West Nile virus status

[ODFW News]

Oregon Department of Fish and Wildlife 	
For more information call 800-720-6339 (ODFW) or 503-947-6002	
Internet: www.dfw.state.or.us  


For immediate release	Wednesday, Sept. 22, 2004


ODFW monitoring West Nile virus status 
Biologists concerned about impact on wildlife, recommend safety precautions for anglers and hunters


SALEM - The arrival of West Nile virus in Oregon has Oregon Department of Fish and Wildlife biologists monitoring the impact of the virus on wildlife populations and reminding anglers, hunters and other outdoor recreationists to take appropriate precautions when outside or around potentially infected animals. 

Impact on wildlife

Birds from more than 234 species have been reported as suffering deaths from West Nile virus since it was first detected in the United States in 1999. Those species include waterfowl, hawks, owls, upland game birds and songbirds.  

"Other wildlife species also are severely affected by the virus," said Colin Gillin, ODFW Wildlife Veterinarian. "In areas where virus-carrying mosquitoes and sage grouse occur together, the grouse that are infected have experienced close to 100 percent mortality. Infected crows and jays are dying at a similar rate. It also appears that tree squirrels may suffer an elevated risk of succumbing to the disease."

But these are the most severe cases among birds and wild mammals, noted Gillin. 

"At this point," said Gillin, "most wildlife species appear to survive infection. Once the disease passes, the animal is protected with lifelong immunity."

Impact on humans

Not all species of mosquitoes carry the virus. The chance of being bitten by a mosquito carrying the virus is very low, according to the national Centers for Disease Control and Prevention, even in areas where the virus has been reported. And once bitten, even by a mosquito carrying the virus, infection is not a certainty.

Estimates suggest fewer than 20 percent of people infected with West Nile virus develop any illness. Mild symptoms include fever, headache and body aches possibly accompanied by a skin rash or swollen lymph glands. In a small number of people (1 in 150 people infected) the virus crosses into the nervous system and can cause inflammation of the brain (encephalitis) or spinal cord (meningitis). The incubation time in humans is 5-15 days. Currently, no drugs or vaccines are available to treat or prevent infection. 

Report sightings of dead birds

ODFW biologists are urging the public to keep alert for clusters of recently deceased jays, crows, magpies and ravens. This family of bird species, known collectively as Corvidae, is particularly susceptible to the virus and, once infected, often die quickly from the disease.  When birds in a flock are infected, multiple dead birds may be seen in a single location, such as under a roosting tree. Finding clusters of dead crows or jays may be an early indicator of where the virus has spread. Unusual sightings of clusters of dead crows, jays, magpies or ravens should be reported to the county health department or local ODFW office for removal and testing. 

Take precautions when outdoors

Hunters (as well as all other outdoor recreationists) may be at risk if they become bitten by mosquitoes in areas where West Nile virus is known to be active. People can reduce their chance of being infected with West Nile virus by taking preventive measures. 

The national Centers for Disease Control and Prevention advise people to:

*	Apply recommended mosquito repellents and wear protective clothing when outdoors.
*	Use and maintain screens on all windows and doors.

Health officials suggest using a mosquito repellent that provides protection for the amount of time a person will be outdoors. People should be sure to follow all application instructions to avoid irritating their skin, eyes and mouth, or using too much on young children. Mosquitoes can bite through thin clothing, so people also may want to spray their clothing with a repellent. It's also a good precaution to place mosquito netting over infant carriers. 

Handle potentially infected animals carefully
 
While there currently is no conclusive evidence that West Nile virus can be spread from animals to people, individuals should contact their veterinarians on infection control precautions when caring for a sick animal. Care should be taken around sick animals because the virus theoretically can be aerosolized, or gain entry via a sick animal's blood or other secretions into a person's open cut or from hand to mouth. 

"Game animals that may harbor the virus but are not clinically affected pose little risk," said Gillin. 

As with any wild game species, prudent meat-handling precautions should be taken, noted Gillin. The virus is destroyed with heat, so adequate cooking of game meat is always a wise practice. 

Control mosquito breeding areas

Mosquitoes responsible for transmitting the West Nile virus, such as Culex species and Aides species, are not common to wetlands. They prefer standing water high in organic materials such as leaf-clogged gutters and unattended birdbaths. 

Wetlands are not generally a source of stagnant water. In healthy natural wetlands water levels fluctuate, constantly moving water around, which limits mosquito production. Also, birds and insects in a wetland area feed on mosquitoes and mosquito larvae, thereby reducing the numbers. If a wetland is disturbed by humans, or if other life forms are eliminated through the incorrect use of pesticides, it is possible that the numbers of mosquitoes in a wetland actually may increase. Therefore, it is important to preserve the natural balance in a wetland.

The best way to keep mosquitoes at bay is to control breeding grounds in yards and near homes by disposing of standing water. Hundreds of mosquitoes can breed in just a tablespoon of stagnant water, so people are encouraged to be vigilant about eradicating even small amounts of standing water near homes and in yards.
 
"People can reduce the numbers of mosquitoes in areas where they work or recreate," said Gillin, "by periodically draining sources of standing water such as flower pots, birdbaths, swimming pool covers, livestock and pet water dishes and bins, and miscellaneous buckets and barrels."

Get more information

More information about West Nile virus is available at:

*	Oregon Department of Human Services http://www.dhs.state.or.us/publichealth/acd/wnile/index.cfm 

*	Centers for Disease Control	http://www.cdc.gov/ncidod/dvbid/westnile 

*	National Wildlife Health Center  http://www.nwhc.usgs.gov 

*	Portland Audubon  http://www.audubonportland.org 

*	Oregon West Nile Virus Information Line  866-703-4636 (toll free)

*	OSU Extension Service  http://extension.oregonstate.edu/lane 

*	U.S. Geological Survey National Wildlife Health Center:  http://www.nwhc.usgs.gov/research/west_nile/west_nile.html 

*	Audubon Society of Portland   http://www.audubonportland.org/wnv.html 

*	Northwest Coalition for Alternatives to Pesticides http://www.pesticide.org/westnilevirus.pdf 


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