CA Dept. of Public Health UC Davis Arbovirus Research and Training Mosquito and Vector Control Assoc. of CA

Case Counts by County

CountyDead birds
Alameda10
Alpine-
Amador-
Butte1
Calaveras-
Colusa-
Contra Costa3
Del Norte-
El Dorado2
Fresno-
Glenn-
Humboldt1
Imperial-
Inyo-
Kern-
Kings-
Lake-
Lassen-
Los Angeles4
Madera-
Marin-
Mariposa-
Mendocino-
Merced-
Modoc-
Mono-
Monterey-
Napa-
Nevada-
Orange1
Placer19
Plumas-
Riverside3
Sacramento181
San Benito-
San Bernardino-
San Diego-
San Francisco-
San Joaquin7
San Luis Obispo-
San Mateo2
Santa Barbara-
Santa Clara26
Santa Cruz2
Shasta-
Sierra-
Siskiyou-
Solano-
Sonoma-
Stanislaus1
Sutter3
Tehama-
Trinity-
Tulare-
Tuolumne-
Ventura-
Yolo19
Yuba-
Total285

WNV Activity by County
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2007

Press Releases

EARLY ONSET OF WARM WEATHER TRIGGERS AN EARLY WEST NILE VIRUS SEASON

Apr 23, 2007

SACRAMENTO - Unusually high temperatures throughout the state in March triggered an earlier than normal start to the West Nile virus (WNV) season, State Public Health Officer Dr. Mark Horton warned today.

"Mosquitoes that carry West Nile virus are breeding earlier this year due to warm weather," Horton said. "While no predictions can be made about the severity of West Nile virus this season, Californians should begin taking precautions to protect themselves from mosquito bites by eliminating all sources of standing water that can support mosquito breeding and applying insect repellent containing DEET."

WNV was first detected in California five years ago. So far this year, no human cases of WNV have been identified. However, the virus has been detected in mosquito pools, sentinel chickens or horses in eight counties: Imperial, Los Angeles, Orange, Riverside, Santa Clara, San Diego, Sonoma and Stanislaus.

In 2006, a total of 292 human WNV infections, including seven deaths, were reported in the 54 counties that detected WNV activity. Of the 58 horses that also tested positive for WNV, 24 died or were euthanized. WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds.

Governor Arnold Schwarzenegger has invested a total of $15 million over the last two years to enhance mosquito control efforts. This funding has supplemented the resources of existing mosquito control programs statewide and expanded efforts in areas of the state not covered to combat WNV. This investment in equipment and other products to control mosquitoes continues to benefit mosquito control efforts this year.

Horton reminded Californians of three simple ways to protect themselves from WNV:


  • DEET - Apply inspect repellent containing DEET, picaradin or oil of lemon eucalyptus according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.

  • DAWN AND DUSK - Mosquitoes that carry WNV bite in the early morning and evening so it is important to wear repellent at this time. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.

  • DRAIN - Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old car tires, rain gutters and pet bowls. If you have a pond, use mosquito fish or commercially available products to eliminate mosquito larvae.

California's WNV Web site - www.westnile.ca.gov - has been updated to make it easier for the public to find the latest information on WNV activity in the state. In addition to reporting all dead birds, Californians are encouraged to report dead tree squirrels, three types of which have tested positive for WNV in California: the Western Gray, Fox and Eastern Gray. The Web site also includes information on the most common birds found with WNV. Dead birds and squirrels can be reported on the Web site or by calling (877) 968-2473.

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Compared to previous year and previous five-year average to date

As of Aug 10, 2018201820175Y AVG
Counties333136
Human cases192232
Dead birds285172657
Mosquito samples94218051679
Sentinel chickens3858113
YTD - Year to date corresponds to the same time last year or last five years.

- view all 2018 YTD activity -

WNV Reports

Weekly Report

08.13 2018 YTD SLEV Activity Map
08.13 2018 YTD WNV Activity Map
08.10 Arbovirus Bulletin #19

Humans

08.09 2018 Human WNV Incidence Report
08.09 2003-2018 WNV Case Summary
03.29 2017 Human WNV Incidence Report

Dead Birds

08.10Reported, Tested, Positive 2018
08.10Positive Species for 2018
08.10Positive Counts by City/County for 2018

Mosquitoes

08.10 AMOR - EVS Week 31
08.10 AMOR - GRAVID Week 31
08.10 AMOR - NJLT Week 31
- view report archives -