West Nile Virus
West Nile fever is an illness caused by the West Nile Virus (WNV), believed to be carried into the U. S. by a bird, person, or mosquito. It begins with flu symptoms, and may progress to coma and death in 3-15% of infected people. The elderly are more apt to die. Symptoms may include a rash and weakened leg muscles. One in 50 infected people will develop serious symptoms of encephalitisãswelling of the brain.
Birds are the host for this virus (where it lives) and mosquitoes are the vector (mode of transmission). If an infected mosquito takes a "blood meal" from (i.e., bites) a human, the mosquito can transmit the West Nile Virus to that person. In 1999, for the first time, the West Nile Virus was found in the U. S., causing an outbreak of West Nile encephalitis in New York City, resulting in 62 severe cases and 7 deaths. While additional cases occurred in 2000 and 2001, there was a dramatic increase in West Nile virus cases and in the area affected by the virus in 2002. There were more than 4000 human cases reported, and 284 deaths, and the virus spread as far as the West Coast.
Anyone can become ill from a West Nile Virus infection, however people over age 50 are most at risk of severe diseases coma and death.
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Yes, WNV can be prevented if people protect themselves against mosquito bites and breeding. People in the U. S. are not used to thinking of mosquitoes as disease-carrying insects however West Nile virus is now a risk in nearly all US states. To prevent WNV and other mosquito-borne diseases, mosquito breeding places such as stagnant pools, discarded tires, sewage drains, and backyard flower pots must be drained. Few people know about the risks of mosquito breeding grounds in their yards or community. Warm weather can expand the timeframe and regions in the U. S. for this disease to circulate.
West Nile virus is a clear example of new disease threats emerging from an increasingly small world. CDC experts believe that a person, bird, or mosquito infected with West Nile could have been transported by airplane to the U. S., causing the outbreak in New York. We are less than 24 hours away from diseases of Asia and Africa.
- INFORM viewers that they may be at risk for diseases from common backyard mosquitoes.
- EDUCATE viewers that they have a rare opportunity to stop an emerging infectious disease from taking hold in the U. S. by removing mosquito breeding places on their property.
- REMIND the elderly that they are at greater risk and should limit their time outdoors to dawn and dusk or wear long sleeves and pants and apply an insect repellant containing DEET.
- EXPLAIN that every year the CDC discovers a new virus; that the threat is only a plane ride away.
- REASSURE the viewer that diseases can be prevented when correct measures are taken. They have an important role in controlling disease as individuals and members of a community.
Harold, a 67-year-old retiree, has a townhouse on a tiny plot of land; he prides himself on the patch of grass and special roses he's grown. This summer, the city is experiencing a water shortage; water use is restricted. Harold has set out containers to catch rainwater during the rare afternoon shower to use on his roses. He sits outside every evening before dinner. He's been feeling achy, kind of flu-like, unusual in summer, and he's had a flu shot. Within days, he's in the hospital in a coma. He has encephalitis. Doctors diagnose viral encephalitis and go looking for the cause. West Nile Virus is identified and the city must go into "emergency" mode to kill mosquitoes. Harold recovers, but others are not so fortunate.
- Page last reviewed: February 24, 2011
- Page last updated: February 24, 2011
- Content source:
- Centers for Disease Control and Prevention
- Page maintained by: Division of Public Affairs (DPA), Office of the Associate Director for Communication (OADC)