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

Division of Environmental Health


Date Released: 7/2/2010
Subject: West Nile Virus Season has Started in California
Contact: Kevin Metcalfe
Phone: (707) 445-6215

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

So far this year no human or horse cases of WNV have been detected in California. However 27 birds from eight counties in the Central Valley and Southern regions of the state have tested positive for WNV infection in 2010.

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 in California.

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

DEET- Apply insect repellent containing DEET, Picaridin or oil of eucalyptus according to label instructions. Repellents keep mosquitoes from biting you. For more information about repellents contact the National Pesticide Information Center (NPIC) through their toll-free number, 1-800-858-7378.

DAWN and DUSK Mosquitoes that carry WNV bite early in the morning and in the evening. Take extra care to use repellant and wear protective clothing or limit outdoor activities during 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.

Residents are strongly encouraged to contact the Humboldt County Division of Environmental Health, at 445-6215 or toll free at 1-800-963-9241, when concentrations of mosquitoes or manmade/artificial breeding sources are encountered. This will assist us in our tracking and monitoring information.

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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