What you should know
about this outdoor danger

It’s the West Nile virus, named after the area in which it was first discovered in 1937. Infected mosquitoes spread the disease, which can cause an inflammation of the brain and spinal cord. If it’s reported in your area, avoid taking your indoor parrot outdoors. If your birds live or spend time in an outside aviary, you’ll want to use mosquito-blocking netting.

Discovered in Uganda
Before it appeared in the United States almost three years ago, the West Nile virus was known in other parts of the world - mostly Africa, the Middle East and tropical Eurasia - for causing human epidemics. So far in this country, it has killed mostly animals, especially birds.

Mosquitoes and birds pass the virus back and forth. Mosquitoes that feed on diseased birds incubate the virus for up to 14 days before becoming infectious. Birds can pass the virus back into the mosquito population between one and four days after they're bitten. Survivors enjoy a life-long immunity.

Mammals are considered dead-end hosts because the virus isn’t present in high enough levels in the blood to reinfect the mosquito population.

New York hit hard
The virus first made headlines in the United States in October 1999, when over 80 people in Queens became ill and nine died. Several thousand crows in the area and flamingos, cormorants, bald eagles, magpies, ducks, owls and other birds at local zoos also died.

Since then, few people have become ill with West Nile virus, but it continues to crop up in bird deaths pushing westward and south across the United States.

After a slow start, the West Nile virus “blossomed” last year, making its way as far west as Louisiana and eastern Iowa, said Dr. Roy Campbell, a Ft. Collins, Colo., medical epidiomologist for the Center for Disease Control who has followed the virus since a 1996 outbreak in Europe.

According to ArboNET, a surveillance database maintained by Tulane University Center for Infectious Diseases, West Nile virus has now been reported in 27 states, Washington, D.C., Ontario, and the Cayman Islands.

Geography could slow down the virus' progression, says Campbell. “Nobody knows what’s going to happen when it hits the Rocky Mountains,” he notes.

The virus might make the jump via eastern U.S. birds that migrate to South America and spread it there. Then other migrating birds could bring it north up the west coast.

Or an infected mosquito trapped in a cargo truck could bring it west. “It hasn’t been documented, but it’s certainly possible,” said Campbell.

How to track it
So far, the virus is estimated to have killed birds in 100 species in this country alone.

“Over time - decades, or maybe only a few years - you won’t see bird mortality because those that have resistance and survive will continue to reproduce," said Campbell. "Nature is weeding out the American crow right now.”

When that happens, our captive birds will not be as susceptible to the virus because there will be fewer mosquitoes feeding on infected birds in the wild.

Until then, parrot owners should take precautions. If you live in an infected area, avoid taking your bird outdoors, especially at dusk or during the warm-weather mosquito season, generally any time before the first hard frost.

If you’re not sure whether you live in an infected state, check to see if any warnings have been posted at your department of public health’s Web site. Find yours at the CDC's Links to State and Local Government Sites page.

To find out if your neighborhood is in danger, contact your mosquito control district. They usually have a vector-borne disease monitoring program in place to determine if arboviruses (viruses spread by mosquitoes) are active locally. For a list of mosquito control districts and mosquito control associations, visit the American Mosquito Control Association.

“The key is mosquito control,” says Campbell. "Some states and localities are better than others at eliminating water sources and monitoring the breeding areas that can’t be eliminated."

Don’t let low-sounding infection rates fool you, he says. “A rate of 1 in 1,000 mosquitoes is extremely high. If someone quotes that, it’s time to worry because it means there is a rampant infection going on.”