How does West Nile virus spread?

• Infected mosquitoes. Most often, West Nile is spread by the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds. Infected mosquitoes can then spread West Nile to humans and other animals when they bite.

• Transfusions, transplants, and mother-to-child. In a very small number of cases, West Nile also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby.

• Not through touching. West Nile is not spread through casual contact such as touching or kissing a person with the virus.

• How soon do infected people get sick? People typically develop symptoms between 3 and 14 days after they are bitten by the infected mosquito.

• How is West Nile infection treated? There is no specific treatment for West Nile infection. In cases with milder symptoms, people experience symptoms such as fever and aches that pass on their own, although even healthy people have become sick for several weeks. In more severe cases, people usually need to go to the hospital where they can receive supportive treatment including intravenous fluids, help with breathing and nursing care.