West Nile virus (WNV) is a mosquito-borne virus commonly found in Africa, Asia, the Middle East and, since 1999, in North America. West Nile virus is usually transmitted to people and animals through the bite of an infected mosquito. A mosquito acquires the infection by feeding on a bird with virus in its blood. 

Approximately 80 percent of the people who are infected with WNV will not show any symptoms.  Less than 1 percent of the people infected with WNV will develop severe illness.  The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.  These symptoms may last several weeks, and neurological effects may be permanent.  West Nile virus infection can be fatal.  People over 50 and those who are immunocompromised have a higher chance of getting sick when infected with WNV and should take special care to avoid mosquito bites.  Call your doctor if you have questions. 

There are steps you can take to reduce your risk of mosquito bite. 

Drain all sources of standing water that can support mosquito breeding.  Those that cannot be drained should be maintained to minimize mosquito propagation.  Operate the filter and maintain disinfectant in swimming pools and spas.  Mosquito fish or other species in ponds that prey on mosquito larvae help provide control.  Mosquito dunks can be used in pooled water that does not support mosquito fish or other predators.

Avoid spending time outside when mosquitoes are most active, typically dawn and dusk.   If you need to be outdoors during these peak activity periods, wear long pants and long-sleeved shirts.  Apply insect repellent according to label instructions.  Repair and replace door and window screens that have tears or holes to keep mosquitoes out of your home.  

For more information:

https://www.epa.gov/insect-repellents/find-repellent-right-you

http://www.cdpr.ca.gov/docs/dept/factshts/repellents.pdf

https://www.cdc.gov/westnile/prevention/index.html

http://www.westnile.ca.gov/wnv_faqs_basics.php

https://www.epa.gov/insect-repellents/deet#safety

For more information on West Nile Virus visit www.westnile.ca.gov. To report a dead bird or dead tree squirrel call 1-877-WNV-BIRD.