West Nile Virus
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What is the West Nile virus?
The West Nile virus is spread by the bite of an infected mosquito.  It can infect people, birds, horses, and other animals.  Most people infected by the virus will have either no symptoms or only mild ones.  However, on rare occasions, the infection can result in severe and sometimes fatal illnesses. There is no evidence to suggest that West Nile virus can be spread from person to person or from animal to person.

West Nile Virus is a flavivirus commonly found in Africa, West Asia, and the Middle East. It is closely related to St. Louis encephalitis virus found in the United States. West Nile fever is a case of mild disease in people, characterized by flu-like symptoms (mild fever, body aches, a rash, swollen lymph glands). West Nile fever typically lasts only a few days and does not appear to cause any long-term health effects.  More severe disease due to a person being infected with this virus can be West Nile encephalitis, West Nile meningitis or West Nile meningoencephalitis. Encephalitis refers to an inflammation of the brain, meningitis is an inflammation of the membrane around the brain and the spinal cord, and meningoencephalitis refers to inflammation of the brain and the membrane surrounding it (symptoms include: headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions muscle weakness, paralysis, and rarely death). It is estimated that 1 in 150 persons infected with the West Nile virus will develop a more severe form of disease. The incubation period is 3 - 14 days.  Persons over 50 years of age have the highest risk of severe disease. It is unknown if immunocompromised persons are at increased risk.

How is a West Nile virus infection treated?
No vaccine is available although research is being conducted.  There is no specific treatment for an infection.  More severe infections such as menigitis and encephalitis are treated in the standard fashion with supportive care.

Avoid mosquito bites by applying insect repellent when going outdoors (repellents containing DEET [N,N-diethyl-m-toluamide] are the best).  Wear long sleeves and pants when outside.  Eliminate standing water around your house where mosquitos can breed.  Install window and door screens on your house.

CDC West Nile virus basics
CDC Insect Repellent Use and Safety
CDC Clinical Guidelines for Treatment

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Copyright © 2001-2002 Scott Toste, Pharm.D., R.Ph.
Last updated: 10/13/02