West Nile Virus (WNV)



What is WNV?

West Nile virus (WNV) is a mosquito-borne disease that was originally found in Africa. In 1999, it was detected in the eastern United States; since then the virus has spread throughout the United States and is well established in most states, including California.


How do people contract WNV?


How soon do infected people get sick?

People typically develop symptoms from 3 to14 days after they are bitten by an infected mosquito.


What are the symptoms of WNV?

Symptoms vary:


Who is at the greatest risk of getting severely ill from WNV?


How is WNV infection treated?

There is no specific treatment for WNV infection. In cases with milder symptoms, people experience fever and aches that pass on their own. In more severe cases, people may need to go to the hospital where they can receive supportive care including intravenous fluids, help with breathing, and nursing care.


If you have had WNV, are you immune to further infections?

It is thought that once a person has recovered from WNV, they are immune for life to future infections with WNV. This immunity may decrease over time or with health conditions that compromise the immune system.


Can animals get sick with WNV?

An infected mosquito can bite any animal, but not all animals will become sick. The disease most often affects birds but may occasionally cause disease in other animals.

WNV Video