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West Nile Virus

by Michael Loomis

A war rages along our Atlantic Seaboard and the Gulf Coast. Thousands of birds have already died in this war, and millions of dollars have been spent to combat the foe. The enemy: the West Nile virus, a deadly disease never before encountered by the birds in North America. With your help, this epidemic may be slowed, halted, and possibly reversed.

The West Nile virus was first isolated in the West Nile District of Uganda in 1937, but only recently has it been detected in North America. The virus is primarily a disease of wild birds; it is spread from bird to bird and from bird to mammal by the bite of a female mosquito. Besides killing birds, the virus can cause deadly brain diseases in humans and horses.

That said, please don’t panic. The odds of humans contracting the West Nile virus are extremely low, and birds themselves pose no threat to humans. The virus cannot be transmitted directly from birds to people or from people to people. You cannot get the virus from touching a live or dead infected bird. Infected mosquitoes (which only bite LIVE birds) are the principal transmitters of the virus.

Here are some reassuring facts: Even in areas where the virus has been detected, less than 1% of mosquitoes are carriers. And even if bitten by an infected mosquito, less than 1% of humans would become ill. Of the tiny amount of the human population that becomes ill, most exhibit only mild flu-like symptoms. Even among the elderly, who are the ones most at risk, the chances of severe infection are low.

How did this insidious virus reach our shores? No one knows. An infected bird may have been smuggled into the U.S. from Africa or Asia. Or virus-infected mosquitoes may have hitched a ride n a plane or in the hold of a ship. The good new is, which the exception of American Crows and other corvids, there are only a few individual birds from 18 species that have hosted the virus.

Crows and jays appear to be highly sensitive to the virus. As many as 10,000 crows died of the disease in metropolitan New York in 1999. Some people have blamed crows for spreading the disease, but scientists think that is unlikely. Crows are victims, not the bad guys. But like the canary in the mineshaft, crows can alert us to the presence of the virus in time to limit the damage done by infected mosquitoes.

If you find a dead jay or crow, call Santa Clara County Vector Control at 408-792-5010 or the state hot line at 877-968-2473. WCSV will comply with all recommendations of the Health Department and CDC when West Nile reaches the Bay Area.

This article originally appeared in the “Wild Bird News,” a publication of the Wild Bird Center of Los Gatos. Reprinted with permission.

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