Air Date: Week of July 27, 2001

Living on Earth's Diane Toomey reports on a study that suggests the West Nile Virus outbreak of 1999 could have caused more infections than previously thought.

Transcript

CURWOOD: Coming up: Capital Hill is moving ahead with changes in fuel efficiency standards for cars and light trucks. First, this health note from Diane Toomey:

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TOOMEY: In the summer of 1999, a slew of dead birds in New York was the first sign to alert health officials that the West Nile Virus had made its way from Africa and the Middle East to the U.S. In the vast majority of people, the virus may cause, at most, short term flu-like symptoms. In those who are more vulnerable, such as the elderly, the virus can cause lethal swelling of the brain. Eventually, New York State reported 62 cases of the mosquito-borne disease, including seven deaths.

But a group of scientists has found evidence that those numbers may underestimate the rate of infection. Six weeks after the initial outbreak, researchers from New York City's Department of Health went door-to-door in northern Queens, where nine cases of the virus had been reported. Researchers took blood samples from almost 700 people and analyzed them for antibodies to West Nile. They found 15 people were carrying Immunoglobulin M, which means they'd recently and unknowingly been infected with the virus. From this data, scientists estimate for every one reported case of West Nile, there are 140 milder cases that go undiagnosed.

Since then, West Nile virus has made its way down the East Coast. This year the first confirmed human case of West Nile has been found in Florida's Madison County. Researchers now suggest that doctors consider the possibility of West Nile when diagnosing patients with summertime fevers and flu. That's this week's Health Note. I'm Diane Toomey.

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CURWOOD: And you're listening to Living On Earth.

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