How Do People Know They Have West Nile Fever?

The first symptoms of WNV infection are usually fever, headache, and body aches, sometimes accompanied by a rash and swollen lymph nodes. Serious cases of the disease may cause more severe symptoms, including high fever, stiff neck, muscle weakness, convulsions, confusion, paralysis, and coma. Very severe cases can result in death, but this is rare. Symptoms usually begin 3 to 15 days after infection.

How Is West Nile fever Diagnosed and Treated?

If WNF is suspected, the first step for the physician is take a history, which means asking a person about prior health, when symptoms began, and recent travels and activities. This may help determine if the person might have been exposed to an infected mosquito. A blood test can confirm the presence of the virus.

For mild cases of WNF, no specific treatment exists. A doctor usually recommends rest and over-the-counter medications, such as acetaminophen, to ease fever and aches. Severe cases of WNF may require hospitalization and more specialized care, such as intravenous (in-tra-VEE-nus) fluids (fluids given directly into a vein) to prevent or treat dehydration in someone who is too sick to drink or who is vomiting. A person who is having trouble breathing may be put on a ventilator.

How long WNV illness lasts depends on the severity of the infection. If a person has a mild infection, symptoms often go away in about a week. Recovery from serious infection may take several weeks to months. Most people who are infected with WNV do not become very sick. Only about 1 percent of all infected people become severely ill. Of these severe cases, up to 15 percent are fatal. Elderly people have the highest risk of developing serious complications from the disease.

Can West Nile Fever Be Prevented?

No vaccine is available for WNF, so the best way to prevent the spread of the virus is to prevent mosquito bites. To do so, experts recommend that people avoid being outside at times when mosquitoes are most active (dawn, dusk. and early evening), that they wear long sleeves and long pants, and that they use insect repellent when outside. When using repellent, everyone, especially children, should carefully follow the instructions on the package. 

In the United States, health officials have often traced WNV to areas where dead birds have been found. By tracking the disease and looking for patterns of infection, public health officials are better able to prevent future outbreaks. Experts advise people to contact the local or state health department if a dead bird is found in an area where WNV has been reported; а representative will collect the bird for testing.

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