West Nile virus is a viral disease of birds that is transmitted from bird to bird by way of a mosquito bite. It can occasionally cause meningoencephalitis (inflammation of the brain and spinal cord) in susceptible people or animals that are bitten by infected mosquitoes. Most people who contract the virus will have few or no symptoms and will recover completely. About 1 in 150 people who contract the disease may develop serious complications. Elderly people are more at risk of such complications. There is currently no vaccine or specific treatment available. If you think you or a family member may have West Nile virus, please contact your physician.

West Nile Virus Questions and Answers

 The Importance of Reporting Dead Birds

While the Contra Costa Mosquito & Vector Control District cannot test every bird that is collected for West Nile virus, reporting them alone are crucial to our surveillance efforts. Click here to report a dead bird.

Out of the 23 species of mosquitoes found in Contra Costa County, two species are known transmitters of West Nile Virus. 

 How YOU Can Protect Yourself