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Maps and Data  > 2007 WNV Activity by County Jul. 3, 2009 10:38AM

West Nile virus has been detected in 19/ 58 California Counties in 2007.

2007 WNV Activity by County

Total Positive Counties: 19

CountyHuman CasesHorsesDead BirdsMosquito SamplesSentinel ChickensSquirrels
State Totals00889751
Alameda--5---
Alpine------
Amador------
Butte------
Calaveras------
Colusa------
Contra Costa---11--
Del Norte------
El Dorado------
Fresno--3248-1
Glenn------
Humboldt------
Imperial------
Inyo------
Kern--98--
Kings--3---
Lake------
Lassen------
Los Angeles--824-
Madera--41--
Marin------
Mariposa------
Mendocino------
Merced------
Modoc------
Mono------
Monterey------
Napa------
Nevada------
Orange--41--
Placer------
Plumas------
Riverside--15--
Sacramento--11--
San Benito------
San Bernardino--1---
San Diego--11---
San Francisco------
San Joaquin--23--
San Luis Obispo------
San Mateo------
Santa Barbara------
Santa Clara--414--
Santa Cruz------
Shasta--1---
Sierra------
Siskiyou------
Solano------
Sonoma------
Stanislaus--2---
Sutter---1--
Tehama------
Trinity------
Tulare---2--
Tuolumne------
Ventura------
Yolo----1-
Yuba------
State Totals00889751


* A mosquito sample, or "pool," is a collection of approximately 50 mosquitoes that are tested together for West Nile virus.

** WNV and SLE (St. Louis encephalitis) are closely related viruses in the family Flaviviridae and preliminary testing cannot distinguish between these two viruses.  Further testing is conducted as needed to determine if the sentinel chickens are antibody positive to WNV or SLE.

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