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Friday, December 10, 2010 - Page updated at 04:23 p.m.

West Nile virus

West Nile virus

West Nile virus (WNV) causes West Nile fever and West Nile meningitis, encephalitis and West Nile poliomyelitis. It can infect people, birds, mosquitoes, horses and other animals. In Washington state, the virus was first found in horses and birds in 2002; the first human infection in Washington state occurred in 2006.

Three steps to prevent mosquito bites

• Wear long sleeve shirts, long pants, socks and a hat

• Wear light-colored clothing (mosquitoes are attracted to dark colors)

• Use an insect repellent

Repellents for use directly on skin

The Centers for Disease Control and Prevention recommends the use of insect repellents that include active ingredients which have been registered by the U.S. Environmental Protection Agency (EPA). The following active ingredients have been reviewed and approved by the EPA for effectiveness and human safety if applied according to the instructions on the product label.


• Picaridin or KBR 3023

• Oil of Lemon Eucalyptus or PMD, the synthesized version of lemon eucalyptus

• IR3535

West Nile symptoms

Most people who are infected with the West Nile virus will not get sick. In those who do become ill, symptoms usually begin between 3 and 14 days after being bitten by an infected mosquito. About 1 in 5 infected persons will develop West Nile fever, a flu-like illness lasting a few days to several weeks. In addition to fever, symptoms include:

• Fatigue

• Headache

• Loss of appetite

• Nausea

• Rash

• Vomiting

• Swollen glands

About 1 in 150 infected people will have one of the more severe and potentially fatal forms of disease (West Nile meningitis, encephalitis or West Nile poliomyelitis) that can include symptoms of West Nile fever and:

• Severe headache

• Neck stiffness

• Decreased level of alertness

• Muscle weakness, tremors, or paralysis

• Sensitivity to light

• Convulsions or coma

Source: Public Health — Seattle & King County