Susan Buckley, RN, Director, Public Health
Ira Singh, MPH, Deputy Director
Donald I. Baird, MD, Health Officer

Division of Environmental Health


Date Released: 6/5/2008
Subject: 2008 West Nile Virus Season
Contact: Kevin Metcalfe, Supervising Environmental Health Specialist, Environmental Health Division
Phone: (707) 445-6215


West Nile Virus Season has Started in California

The Humboldt County Department of Health and Human Services Environmental Health Division wants to remind the public that with summer approaching and temperatures warming up the mosquitoes that carry West Nile Virus (WNV) have emerged in Southern and Central California.

So far this year no human or horse cases of WNV have been detected in California. However sixty-five birds from eleven counties have tested positive for WNV. The virus has also been found in two sentinel chicken flocks in one county and eleven mosquito pools from three counties. WNV has not been detected in any of the coastal counties north of Los Angeles so far this year.

Due to the cooler temperatures in Humboldt County the Culex tarsalis mosquito, the carrier of WNV, is not present in large numbers and its ability to transmit disease is greatly reduced. The Culex tarsalis mosquito is typically present in Humboldt County from mid June to the end of September. Members of the public are advised to take precautions to prevent getting bitten by mosquitoes especially when traveling to areas where WNV is known to exist such as the Central Valley or Southern California.

There are three simple measures the public can take to protect themselves and their families from WNV:

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

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

DRAIN Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including flower pots, old tires, rain gutters, buckets and pet bowls. Bird baths and water troughs should have their water changed weekly. If you have a pond use mosquito fish or commercially available products to eliminate mosquito larvae. Ranchers and farmers are encouraged not to over irrigate their fields. Standing water in fields, adjacent ditches, small ponds, neglected swimming pools and man-made containers are prime breeding grounds for the WNV mosquito.

For more information on WNV contact the Humboldt County Department of Health and Human Services Environmental Health Division at 707-445-6215 or log onto the State of California WNV web site at www. The web site 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 dead birds, Humboldt County residents are encouraged to report dead tree squirrels. The two tree squirrels native to Humboldt County are the Western Gray Squirrel and the Douglas Squirrel. The web site also contains 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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