WNV Surveillance
October 5, 2017

San Mateo County

As of September 28, 2017, there have been 320 dead birds reported in San Mateo County. Of those, 56 have been suitable for testing and 1 has tested positive (2%) for West Nile Virus (WNV). Nine dead squirrels and four mosquito pools have been tested for West Nile Virus in San Mateo County thus far this year, and none of them have tested positive.

The district asks residents to call in to report dead birds or tree squirrels.  Specimens that appear to have been dead for less than 24 hours and are in good condition will be tested for WNV.  Residents should contact the state WNV hotline at 877-WNV-BIRD (968-2473).  Reports can also be made online at


WNV has been detected in 42 counties in 2017 (see map), compared to a five year average of 37 counties at this date. 174 human case of West Nile Virus has been reported in California this year, from seventeen counties, and there have been eight fatalities. Statewide, 6,513 birds have been reported and 1,676 have been tested with 405 positive results (24%).  3,116 mosquito pools have tested positive for West Nile Virus, compared to a five-year average of 2,742 positive mosquito pools at this time. 235 positive sentinel chickens has been reported from fourteen counties.