The facts about the West Nile virus

Previously found in Africa, West Asia, and the Middle East, the West Nile virus was first detected in the United States in 1999. Since that time, the virus has spread rapidly into all 48 continental states, Canada, and Mexico. To date, over 24,000 human cases have been reported in the U.S., and over 900 of those were lethal. Many more unreported cases exhibiting mild or non-clinical symptoms are likely to have occurred.

The virus is transmitted by infected mosquitoes that acquire the virus from the blood of an infected bird. In some cases, the virus has been spread through blood transfusions, organ transplants, and from mother to child during pregnancy or breastfeeding.

Symptoms of mild cases include fevers and aches that resolve on their own. In serious cases, people experience headaches, high fever, tremors, vision loss, and other neurological effects. Neurological symptoms can be long-lasting and the most severe cases can result in death.

More West Nile Facts

Centers for Disease Control and Prevention:
http://www.cdc.gov/ncidod/dvbid/westnile/

World Health Organization:
http://www.who.int/vaccine_research/diseases/vector/
en/index3.html