Protecting Against West Nile Virus

by Food and Drug Administration (FDA)

(Page 3 of 3)

Keeping the Risk in Perspective

Despite the risk of getting WNV through blood products, organs, and breast milk, these forms of transmission appear to be rare, according to the CDC. Bites from mosquitoes carrying WNV remain, by far, the most common means of transmission.

"While striving to keep blood as safe as possible, it is also important to keep a risk, even a poorly understood risk, in perspective," says Goodman, who emphasizes that only a few dozen cases of possible WNV transmission by blood transfusions are under investigation, out of the more than 4 million people who receive blood each year.

"Blood products and organ transplantation are often lifesaving, or life-enhancing," adds Goodman. "For people who need a transfusion or transplant, our current knowledge suggests that the potential benefits will outweigh the risks, including the risk of West Nile virus infection. The FDA, along with other components of the Department of Health and Human Services, will continue to do everything possible to determine the degree of this risk, and will find and take all available steps to reduce it."

Here to Stay

The West Nile virus (WNV), first found in Africa in 1937, was identified in the Western Hemisphere for the first time in 1999 in the New York City area. Since then, it has spread quickly throughout most of the United States. From January 2003 to the end of October 2003, 44 states and the District of Columbia reported more than 7,700 human cases of WNV infection, resulting in 166 deaths.

There are about 200 different species of mosquitoes in the United States, and the WNV has been found in 36 of them, says Emi Saito, V.M.D., M.S.P.H., West Nile surveillance coordinator at the U.S. Geological Survey's National Wildlife Health Center. "No one really knows how it got into this country," says Saito. "It could have been brought in by a migrating bird, an imported bird, a mosquito hitching a ride on a plane or boat, or another host that we don't know about."

No matter what the route, scientists believe WNV is here to stay. The virus needs its natural host, the birds, to multiply, says Saito. "The only way to truly eliminate the virus in the U.S. is to kill every bird and every mosquito." Even if this approach were feasible, the virus could potentially re-enter the country by a migrating bird or by other means, adds Saito.

Protecting Yourself Against West Nile Virus

For people living in areas where West Nile virus is active, the Centers for Disease Control and Prevention recommends the following:

When going outdoors, apply insect repellant containing N,N-diethyl-meta-toluamide (DEET) to bare skin and clothing. Mosquitoes may bite through thin clothing. Products containing 10 percent or less DEET are the most appropriate for children aged 2-12 years. Always follow product instructions when using repellent. (Ultrasonic devices are not effective in preventing mosquito bites.)

Wear loose-fitting clothing that covers legs and arms while in areas where mosquitoes are likely to be present.

To the extent possible, avoid outdoor activities between dusk and dawn, when mosquito activity is greatest.

Ensure that window and door screens are in good repair and that other routes of mosquito access to buildings and living space are blocked.

Clean out clogged rain gutters to avoid collecting water where mosquitoes can lay eggs.

At least once or twice a week, empty water from flowerpots, pet food and water dishes, birdbaths, swimming pool covers, and other items that collect water.

Protecting Your Pet Against West Nile Virus

Humans aren't the only ones who can get West Nile virus (WNV). The virus is a threat to some animals, too, especially to wild birds and horses. About 40 percent of the horses that developed encephalitis (brain inflammation) from WNV died during the 1999 outbreak that originated in the New York City area. A USDA-licensed equine vaccine for WNV is now available through veterinarians.

WNV has been shown to infect dogs, cats, bats, chipmunks, skunks, squirrels, and domestic birds and rabbits. The virus has rarely caused illnesses in these animals.

Pet owners should not use human repellents that contain DEET on animals. Some animals are more sensitive than people to direct application of DEET products, making their use potentially harmful. Check with your veterinarian for the appropriate products to protect your pet. Also contact your veterinarian if your pet shows signs of WNV infection, such as fever, depression, lack of coordination, muscle weakness or spasms, or seizures or paralysis.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.