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What is West Nile virus?

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West Nile virus is a mosquito-borne zoonotic arbovirus belonging to the genus Flavivirus in the family Flaviviridae and is found in temperate and tropical regions.

First identified in the West Nile subregion in the East African nation of Uganda in 1937, West Nile virus occurred sporadically before the mid-1990s and was considered a minor risk for humans. Now, however, West Nile virus has spread globally — the first case occurred in New York in 1999, and during the next 5 years, the virus spread across the United States, into Canada and south to Caribbean islands and Latin America.

Now considered to be an endemic pathogen in Africa, Asia, Australia, the Middle East, Europe and in the US, West Nile virus killed 286 people in the US in 2012.

West Nile virus is transmitted to humans by mosquitoes. Although most people who become infected with West Nile virus do not experience any signs or symptoms, some develop a life-threatening illness that may lead to inflammation of the brain, known as encephalitis, or inflammation of the tissue that surrounds the brain and spinal cord, known as meningitis.

Immediate attention is required if an infected person experiences severe headache, fever, disorientation or sudden weakness. Otherwise, mild signs and symptoms of the virus generally subside on their own.

Exposure to mosquitoes where West Nile virus exists increases the risk for becoming infected. Using insect repellent and wearing protective clothing to prevent mosquito bites are the only ways to reduce the risk for infection with West Nile virus. There are no medications to treat or vaccines to prevent the infection.

Emptying standing water from flowerpots, gutters, buckets or barrels can decrease mosquito breeding sites. In addition, it is recommended to stay indoors between dusk and dawn when mosquitoes are most active. Keeping screens in windows also will help to keep mosquitoes outside of houses.

Sources:

http://www.cdc.gov/westnile/