West Nile Virus Infection Symptoms

West Nile Virus Infection Signs and Symptoms

West Nile virus (WNV) is a viral infection transmitted by mosquitoes to humans. Currently, there are no specific medicines or vaccines to stop WNV. Data from the U.S. Centers for Disease Control and Prevention reported that WNV infected 2,038 individuals with 94 deaths in the U.S. in 2016; only Alaska, Hawaii, Maine, Delaware, and New Hampshire reported no human infections.

Signs and symptoms of the West Nile virus infection range from no symptoms at all to a rapidly fatal brain infection (encephalitis) in some individuals. In areas where the virus is common (for example, Texas), neuroinvasive disease (spread to the brain and nervous system) was infrequent, but in the last few years, the neuroinvasive infections began to outnumber non-neuroinvasive infections.

The symptoms to be aware of about three to 14 days after an infected mosquito bites a person and transmits the West Nile virus are as follows:

  • West Nile virus infection typically begins with the abrupt onset of fever, chills, muscle aches, headache, and overall feeling of illness. Headache is particularly common and may be severe. The person may have sensitivity to light with pain behind the eyes.
  • Neurologic symptoms can include the above symptoms and neck stiffness, disorientation, coma, tremors, seizures, and/or paralysis.

West Nile Virus Infection Prognosis

Most people fully recover. In others, particularly the elderly and some young children, the disease can progress to cause encephalitis, meningitis, permanent neurological defects, and infrequently, death.

Prevention of West Nile Virus Infection

Prevention of mosquito bites is key to avoiding infection with West Nile virus. The CDC recommends the following:

  • Use mosquito repellent (DEET, picaridin, IR3535).
  • Eliminate standing water where mosquitoes can lay eggs.
  • Fight the bite!

If a person develops any of the symptoms described above about three to 14 days after mosquito bite(s) occur, they should seek medical care for diagnosis and treatment. Although there is no specific West Nile virus treatment or vaccine available for humans, medical management and treatment of the symptoms early on may reduce complications or the severity of the disease.

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United States. Centers for Disease Control and Prevention. "West Nile Virus: Preliminary Maps & Data for 2016." Jan. 18, 2017. <https://www.cdc.gov/westnile/statsmaps/preliminarymapsdata/index.html>.

United States. Centers for Disease Control and Prevention. "West Nile Virus." Sept. 13, 2016. <http://www.cdc.gov/ncidod/dvbid/westnile/index.htm>.