"Personal protection is your best bet" for avoiding the West Nile virus, said Mike Raupp, a professor of entomology at the University of Maryland, College Park. A few prevention suggestions from state and federal authorities:

* On a weekly basis, turn over and empty containers in your yard that can collect water, including kids' toys, trash-can lids, tires and flower pots.

* If you cannot drain a water source, treat the water with mosquito larvicide, available at hardware and garden supply stores.

* Empty and clean birdbaths once a week. Mosquitoes need as little as an inch of still water for breeding, and it takes the eggs about a week to mature to adults.

* Use screens on windows and doors that you often leave open.

* Use insect repellents registered with the Environmental Protection Agency, and follow the instructions on the label. DEET, picardin and oil of lemon eucalyptus have all proven effective against mosquitoes.

* Stay indoors during peak mosquito hours, which are usually dusk and dawn. If you are planning to stay outside for an extended period, wear long and loose-fitting clothes in light colors. Dark colors tend to attract more mosquitoes.

* If you see dead birds around your neighborhood or back yard, report them to the local health department, which will advise you on the best way to dispose of them.

Sources: Centers for Disease Control and Prevention, Virginia Department of Health, Maryland Department of Health and Mental Hygiene.