West Nile Virus

• West Nile Virus Overview
• West Nile Virus Causes
• West Nile Virus Symptoms
• When to Seek Medical Care
• Exams and Tests
• West Nile Virus Treatment
• Self-Care at Home
• Medical Treatment
• Next Steps
• Follow-up
• Prevention
• Outlook
• Multimedia
• Synonyms and Keywords
• Authors and Editors
• Related West Nile virus articles:
  West Nile virus - on WebMD
  West Nile virus - on MedicineNet

West Nile Virus Overview

West Nile virus is transmitted to humans by a mosquito bite. The virus can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the lining of the brain and spinal cord).

West Nile virus was discovered in 1937 in the West Nile district of Uganda. New interest was created when West Nile emerged in the United States for the first time in the New York City area in August 1999. There were 62 confirmed human cases and 7 deaths during this outbreak, creating widespread concern.

• Since the initial 1999 New York City outbreak, the cases of West Nile encephalitis have been relatively limited. In 2002, there were a total of 480 reported cases in humans and 24 deaths (as of August 28, 2002).

• The distribution of the virus is spreading across the United States, as determined from surveillance of infected birds by the Centers for Disease Control and Prevention. In a little more than a year, West Nile spread to 11 states along the East Coast. In 2002, the virus spread to Florida, Arkansas, Louisiana, and Texas. Cases are also being seen in the Dakotas, Colorado, Nebraska, and Wyoming.

• Whether West Nile encephalitis will present a serious health risk to the United States in the future is unknown. Using precautions directed at limiting contact by mosquitoes is the best preventive measure at this time.