West Nile virus (WNV) is an infectious disease that first appeared in the United States in 1999. Infected mosquitoes spread the virus that causes it. People who contract WNV usually have no symptoms or mild symptoms. Those with symptoms may have a fever, headache, body aches, skin rash or swollen lymph glands.

If West Nile virus enters the brain, however, it can be deadly. It may cause inflammation of the brain, called encephalitis, or inflammation of the tissue that surrounds the brain and spinal cord, called meningitis.

Older people are most at risk. There are no specific vaccines or treatments for human WNV disease. The easiest and best way to avoid WNV is to prevent mosquito bites:

• Use insect repellent
• Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets or barrels
• Stay indoors between dusk and dawn, when mosquitoes are most active
• Use screens on windows to keep mosquitoes out