New mode of transmission found for deadly virus

WASHINGTON (Reuters) -- The West Nile virus passed from bird to bird in a laboratory test, a finding that raised new questions about how the virus spreads in the wild, scientists said Wednesday.

Researchers had thought the virus, which has killed eight people in the United States, was transmitted only through mosquito bites.

But scientists housed both healthy and infected crows together at the U.S. Geological Survey's Wildlife Health Center in Madison, Wisconsin. The infected birds died within five to eight days. The healthy birds also became ill, and most died five to eight days after the first infected bird died.

Dr. Robert McLean, the center's director, said researchers were not sure how the virus moved from bird to bird and whether the same thing happens outside a controlled, laboratory setting.

"Mosquitoes are the primary means of transmission of the virus between birds to humans, but this certainly opens up a host of new questions," McLean said in a statement.

He said the findings were more significant for wildlife than for people since humans have a slim chance of contracting the virus from birds directly.

The first West Nile deaths in the United States were reported last year in New York. One man died in New Jersey this year, and infected birds have been found in Maryland, the District of Columbia and North Carolina.

When infected mosquitoes bite people, the virus can cause mild flu-like illness but in rare cases develops into encephalitis.

Encephalitis can kill elderly people or people with weak immune systems, and it can leave healthy elderly victims crippled or disabled.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

President declares West Nile emergency in New York counties
October 11, 2000
3 crows in New York City area confirmed infected with West Nile virus
June 10, 2000

United States Geological Survey
West Nile Virus Maps via CDC

Note: Pages will open in a new browser window

External sites are not endorsed by CNN Interactive.