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Zoos Tracking West Nile Virus
Rare Species Among Those Vulnerable to Mosquito-Borne Illness

audio icon Listen to John Nielsen's report.

A Micronesian kingfisher at Chicago's Lincoln Park Zoo.
Zoo officials worry West Nile virus could be potentially disastrous among obscure and rare populations, such as Micronesian kingfishers, shown above.
Photo: Lincoln Park Zoo

Map documenting the spread of the West Nile virus in the United States
More than 2,400 people have contracted West Nile virus this year, and more than 100 have now died. Brown marks states where humans have been infected, orange marks states with animal-only cases.
View enlargement
View a map of the epidemic's spread, 1999 through 2001.
Graphic: CDC


Most infections in humans are mild, and symptoms include:

Fever, headache and body aches, occasionally with skin rash and swollen lymph glands.

People with weakened immune systems and those over the age of 50 are at risk for more severe infections, including encephalitis, that can cause death. Symptoms include:

Headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

Source: CDC

Oct. 2, 2002 -- The West Nile virus -- fatal to more than 100 Americans so far -- is taking a similar toll at U.S. zoos. By one count, more than 150 zoo animals have died of the mosquito-borne illness since 1999.

Many species of birds are on that casualty list: flamingos, owls, kestrels and hawks as well as penguins, eagles and geese. Emu have perished, and so has at least one Andean condor.

For Morning Edition, NPR's John Nielsen went to Chicago's Lincoln Park Zoo as part of his effort to find out more about what is being done to protect animals in captivity -- and what it might mean for the welfare of Homo sapiens.

Epidemiologist Dominick Travis tells Nielsen there's "no reason to believe" that the atmosphere at a zoo poses a greater danger than any other part of a city where West Nile virus has been detected. In fact, zoos are taking many precautions to improve testing and surveillance programs.

"It's all about getting results as soon as possible so you can act," Travis says.

At some zoos, birds have been injected with a vaccine developed for horses. There's no proof it will work. Other institutions bring the most vulnerable animals indoors at dawn and dusk, when mosquitoes carrying the virus are most active.

An overrriding fear, as Nielsen points out, is that the virus has the potential to put irreplacable animals at risk.

Population geneticist Steve Thompson cites the example of the Micronesian kingfisher. He tells Nielsen there are no more than 65 of the birds left in the world, and all are in North American zoos. They've been kept from extinction for the past 15 years by vigorous human intervention.

"If West Nile were to hit them it could be potentially disastrous," Thompson says.

Health officials are also watching zoos closely, since the virus strikes animals before it reaches people.

"Public health officials used to ignore the West Nile numbers coming out of zoos," Nielsen says. "Now they treat them like intelligence reports."

Local governments and federal agencies are helping zoos improve testing and surveillance programs, hoping to detect the virus as soon as possible.

In Depth

audio icon Wildlife experts say some of the country's best-known endangered species may now be at risk from West Nile virus. Listen to Nielsen's report for Morning Edition. Aug. 23, 2002.

audio icon Louisiana is one of the state's hit hardest by West Nile. Nielsen reports on precautions the state is taking to stop the spread of the virus. Aug. 14, 2002.

browse for more NPR coverage More NPR stories on West Nile virus.

Other Resources

• Chicago's Lincoln Park Zoo.

• The Centers for Disease Control West Nile virus page offers background, how to report dead birds -- which could be a sign of the virus' presence -- and how to contact local and state health departments.

• Links to state health agencies for localized West Nile virus information.

• CDC West Nile virus prevention tips.

• CDC factsheet on prevention and symptoms.

• West Nile virus has been found in more than 100 bird species. The disease can be fatal in some birds, like crows and jays, but most infected birds survive. More about how the disease affects animals.

U.S. Geological Survey West Nile virus project at the National Wildlife Health Center .

• More about West Nile virus in Louisiana from Tulane University

Louisiana Department of Health

U.S. Department of Agriculture West Nile Web page