Symptoms and Signs of West Nile Virus

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 8/30/2021

Doctor's Notes on West Nile Virus

West Nile virus is a mosquito-borne viral illness. West Nile virus usually occurs in birds, and the virus is transferred from birds or animals to humans by the bite of an infected mosquito. 

The majority of people infected with the West Nile virus show no symptoms. When symptoms do occur, they can range from mild to a rapidly fatal brain infection. Early symptoms of West Nile virus infection include

Most patients will recover completely. In a small percentage of patients, the disease can progress to cause encephalitis or meningitis, which may appear as neurological changes such as disorientation, tremors, seizures, headache, high fever, and neck stiffness, and in about 10% of cases, death. 

What is the Treatment for West Nile Virus?

There is no specific treatment for West Nile virus infection. Mild illness does not require therapy other than medications to reduce fever and pain such as acetaminophen (Tylenol) and ibuprofen (Motrin, Advil). 

In cases of severe illness, supportive therapy in a hospitalized setting is necessary to limit complications of brain infections. Anti-inflammatory medications, intravenous fluids, and intensive medical monitoring are essential. 

There is no specific antibiotic or antidote for the viral infection. There is no current vaccine to prevent the virus.

Avoiding areas that have high populations of mosquitoes is key to the prevention of the West Nile Virus. 

The following recommendations can help reduce the risk of becoming infected with the virus:

  • Stay indoors at dawn, dusk, and in the early evening.
  • Wear long-sleeved shirts and long pants when outdoors.
  • Apply insect repellent sparingly to exposed skin. An effective repellent contains 20%-30% DEET (N,N-diethyl-meta-toluamide). Avoid products containing more than 30% DEET.
    • Insect repellents should not be applied to very young children (under 3 years of age) or babies.
    • Repellents may irritate the eyes and mouth.
    • Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.
    • When using insecticide or insect repellent, read and follow the manufacturer's directions for use, as printed on the product.
  • Take preventive measures in and around your home. Repair or install door and window screens, use air conditioning, and reduce breeding sites (eliminate standing water).
  • If you find a dead bird, the Centers for Disease Control (CDC) recommends you not handle the carcass with bare hands. Contact your local health department for instructions.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.