The West Nile virus first emerged in the Western Hemisphere in 1999 in the New York City area and has since spread across the United States. The virus is transmitted to humans by mosquitoes.

Most human infections are mild, causing fever, headache and body aches, often accompanied by a skin rash and swollen lymph glands. If the virus crosses the blood-brain barrier, however, it can cause life-threatening conditions that include inflammation of the brain and spinal cord.

For more information about NIAID research on the West Nile virus, see the following pages:

• Factsheet -- NIAID Research on West Nile Virus.
  A summary of ongoing research supported by NIAID.
• West Nile Virus: Congressional Testimony
  Statement by NIAID Director Dr. Anthony Fauci, M.D., Sept. 24, 2002

News Releases

• January 17, 2006 - Mutation that Protects Against HIV Infection May Raise Risk of West Nile Virus Illness
• April 24, 2005 - Promising New West Nile Therapy Cures Disease in Mice
• April 18, 2005 - NIAID Begins Clinical Trial of West Nile Virus Vaccine
• July 13, 2004 - NIAID Expands West Nile Virus Treatment Trial
• September 8, 2003 - NIAID Opens Innovative Treatment Study for West Nile Virus
• August 18, 2003 - Promising West Nile Virus Vaccine Protects Monkeys
• March 4, 2002 - Two Viruses Team Up in West Nile Vaccine

For More Information

• Centers for Disease Control and Prevention (CDC): Information on West Nile Virus
  The CDC's central site with prevention tips, information on cases, and resources for clinicians and laboratory workers, plus information for kids

• "MEDLINEplus" page on West Nile Virus
  Health information from the National Library of Medicine with general overviews, diagnosis/symptoms, links to related organizations and the latest news

• West Nile Virus Maps
  - 2003 Maps Provisional data from the CDC and the U.S. Geological Survey's Center for the Integration of Natural Disaster Information

• Journal Articles on West Nile Virus in Pubmed
  Links to scientific research articles provided by the National Library of Medicine

• Reports and Updates on West Nile Virus in Morbidity and Mortality Weekly Report
  Epidemiology statistics and other information prepared by the CDC for the medical and scientific community