West Nile Virus

Mosquito closeup biting humanWest Nile Virus season is here.

While there have been no reported human cases of West Nile virus in San Mateo County, it's best to practice good prevention and fight the mosquito bite.  Although most people who become infected with the virus never develop any symptoms, some people may develop a more serious illness, such as meningitis or encephalitis. WNV is a seasonal epidemic in North America that flares up in the summer and continues into the fall. For more information about West Nile Virus, visit WestNile.ca.gov.

West Nile virus in the U.S.

Since 1999, more than 30,000 people in the United States have been reported sick with West Nile virus, which is spread by infected mosquitoes. In the U.S., there have been a total of nearly 700 human cases of West Nile virus disease in 2013, and 26 deaths related to the virus.  This is the highest number of reported cases since West Nile virus was first detected in 1999.  Most cases were reported from six states, including California.  For updated maps and statistics of WNV in the United States, visit the CDC's information page.

West Nile Virus in California

There have been no reported human cases of West Nile virus in San Mateo County.

In California, there have been 181 human cases of West Nile virus reported so far this year. Nine WNV-related fatalities have been reported in 2014. In San Mateo County, 9 bird specimens and 12 mosquito pools were found to be positive for West Nile Virus.

For the most current update, visit www.westnile.ca.gov.

San Mateo County's Mosquito Control Program

The San Mateo County Mosquito and Vector Control District is San Mateo County’s community-based mosquito control program (www.smcmad.org). This program uses different methods to help control the risk of disease in San Mateo County, including surveillance, prevention and control of mosquito populations.

Vector Control does extra mosquito monitoring in neighborhoods where positive birds and squirrels are found.

What you can do to help control West Nile virus:

  • Mosquitoes are most active at dusk and dawn so be sure to use insect repellent, and consider staying indoors or wear long sleeves and pants during these times.
  • Make sure you have good screens on your windows and doors to keep mosquitoes out.
  • Get rid of mosquito breeding areas by emptying standing water from anything that collects water (such as containers, flower pots, pet food and water dishes, swimming pool covers, buckets, etc.).
  • Report abandoned swimming pools by calling San Mateo County Mosquito & Vector Control District at (650) 344-8592.
  • Report a dead bird or squirrel by calling the WNV Dead Bird Hotline at 877-WNV-BIRD (877-968-2473) or click here to submit an online report. The hotline is staffed with live operators from 8:00AM - 4:30PM Sunday through Friday.
  • Help get the word out to your family, friends, neighbors and community. Check out the educational materials below:

For more details about West Nile virus, prevention, what insect repellents to use, and other important information, visit the California West Nile Virus Website.