West Nile virus

West Nile virus is a mosquito-borne virus that can cause a range of symptoms of varying severity in humans. The virus is closely related to viruses that cause St. Louis encephalitis, the most common mosquito-borne encephalitis in the United States, and Japanese encephalitis.

West Nile virus is a mosquito-borne virus that can cause a range of symptoms of varying severity in humans. The virus is closely related to viruses that cause St. Louis encephalitis, the most common mosquito-borne encephalitis in the United States, and Japanese encephalitis.Most people with the virus either don’t have symptoms or have only a mild illness. However, the illnesses caused by West Nile virus may be serious and may include encephalitis, inflammation of the brain, or meningitis, inflammation of the membranes and fluid surrounding the brain and spinal cord.Birds are the main reservoir of the virus. When a mosquito bites an infected bird, the mosquito can spread the virus by biting another bird or another animal, such as a human.West Nile virus is relatively new to the United States, making its first known appearance in August 1999 during an outbreak in New York City. Since then, it has spread rapidly to more than 40 states, infecting birds, humans and horses. In 2002, the Centers for Disease Control and Prevention (CDC) reported more than 4,000 human infections in the United States, compared with less than 150 for the previous three years combined. The virus caused 284 human deaths in 2002 in the United States.Most people who become infected with West Nile virus don’t become seriously ill and recover fully. You can reduce your risk of contracting West Nile virus by avoiding exposure to mosquitoes.(Source: Mayo Clinic, July 1 2003)