West Nile Virus Surveillance
July 7, 2017

San Mateo County

As of June 630, 2017, there have been 215 dead birds reported in San Mateo County. Of those, 45 have been suitable for testing and 1 has tested positive (2%) for West Nile Virus (WNV). No dead squirrels or mosquito pools have been tested for West Nile Virus in San Mateo County thus far this year.

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 seventeen counties in 2017 (see map), compared to a five year average of 23 counties at this date. Three human case of West Nile Virus has been reported in California this year, one each from Kings County, Kern County and Los Angeles County. Statewide, 3,596 birds have been reported and 841 have been tested with 44 positive results (5%).  412 mosquito pools have tested positive for West Nile Virus, compared to a five-year average of 263 positive mosquito pools at this time. One positive sentinel chickens has been reported from Los Angeles County.