West Nile Update

West Nile virus is beginning to peek out from the mysterious hiding places where it overwintered since an outbreak in late 1999. Five additional birds have been found dead with the virus-- four in New York, and one in New Jersey. Officials believed the virus was present in sentinel chicken flocks in Delaware, but the discovery was a false alarm.

West Nile virus (WNV) is a type of encephalitis spread by the bite of an infected mosquito. The virus first was found in birds last fall, and had never been experienced before in the Western Hemisphere. The disease caused illness and death in both horses and humans. For more WNV coverage, visit our web page dedicated to historical facts and news on West Nile.

Two crows in New York were an adult male and female found on May 22. They were submitted from the same area in Rockland County. The New York State Health Department confirmed the presence of the virus on June 9. An additional two birds were found in Rockland County and confirmed positive in late June-- a crow from the Clarkstown area, and a blue jay from the Orangetown area. The New Jersey report involves a dead crow that was found May 30. WNV was confirmed in that bird by the Centers for Disease Control (CDC) on June 8.

In Delaware, blood tests of three sentinel chicken flocks were suspected to be positive for WNV by a quick test done by state agencies. This "preliminary" test, which detected presence of the virus in the birds, was developed this year to detect mosquito-borne diseases rapidly and has proven helpful, but not always conclusive. As mentioned before, the CDC determined that the birds were not positive for West Nile.

West Nile Virus was detected in a dead red-tailed hawk in Bronxville, N.Y. in February, and in adult mosquitoes in Queens, N.Y., during January and February.

"The potential exists for impact on the horse industry," says Randall Crom, DVM, staff veterinarian for the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), and coordinator for West Nile virus issues. "(The incidence of findings) does not mean that there will be human or equine cases, nor does it not mean there will be cases. The impact of this finding is hard to assess. Hopefully, people wonât overreact," he says.

The positive birds are an indication that increased vector surveillance and control is working, and the millions of dollars earmarked by Congress, CDC, and other concerned agencies for these purposes is a worthwhile investment.

Crom believes that since the first of this group of birds was discovered in late May, there might be other dead birds in the process of being tested that could be positive. "I do expect there will be more findings, now that we have initial findings," he said.

In Rockland County, N.Y., officials have not found any West Nile-positive mosquitoes, but Crom believes there must be some present. The pair of positive crows were confirmed to have lived in Rockland County for a while, so it is a likely speculation that there are positive mosquitoes in that county. "As for the bird in New Jersey, I would not speculate (where it picked up the virus)," says Crom.

"I expect there will be other cases found, if not soon, certainly at some point during the summer," he adds.

Birds are one of the possible routes of West Nile's entry into this country. Anyone aware of unusual wild bird deaths is encouraged to contact their state veterinarian or epidemiologist.

"Hopefully, vector control will prevent any human or equine cases from taking place," says Crom.

Editor's Note: Check these two new USDA web sites for more information: http://www.aphis.usda.gov/oa/wnv and http://nationalatlas.gov/virusmap.html.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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