West Nile Virus Surveillance Update
April 28, 2017

San Mateo County

As of April 28, 2017, there have been 56 dead birds reported in San Mateo County. Of those, 15 have been suitable for testing and 1 has tested positive (7%) 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 three counties in 2017 (see map), compared to a five year average of five counties at this date. Statewide, 1,005 birds have been reported and 102 have been tested with three positive results (3%).  One human case of West Nile Virus has been reported in California from Kings County.  No positive sentinel chickens or mosquito pools have yet been reported in California.