West Nile virus is a microscopic organism that has caused outbreaks of deadly disease in horses, birds, and human beings. The virus is named for a province in Uganda where it was first discovered in 1937. Since the 1950’s, the disease has broken out in Africa, the Middle East, Australia, and Europe. In 1999, scientists detected the virus for the first time in the Western Hemisphere. It killed hundreds of birds in the northeastern United States. Since then, health officials have detected the virus in birds and people throughout the United States.
In most cases, the virus causes mild, flulike symptoms. The chief symptoms are fever and headache. In the elderly or people with weakened immune systems, however, the virus can cause encephalitis (inflammation of the brain). It may occasionally cause convulsions, coma, or even death (see Encephalitis). People with severe disease require hospitalization.
The virus is transmitted from infected birds to human beings and other animals through the bites of mosquitoes. There is no known cure or vaccine for West Nile virus. Scientists are concerned that the virus will become a serious threat to public health.
People can reduce their risk of West Nile virus by avoiding areas where mosquitoes are present. It also helps to wear protective clothing and use insect repellents. Public health officials use pesticides to eliminate the mosquitoes that carry the virus. They also drain standing pools of water where mosquitoes breed.
