Press Release

October 18, 2005
Eileen Shields, Public Information Officer, 415/554-2507

Two Birds Identified with West Nile Virus

San Francisco, CA—State health officials have confirmed the presence of West Nile Virus in two birds found in San Francisco, making the City one of the last jurisdictions in the State to identify the virus in its bird population. One bird was discovered in zip code 94131 and the other in 94129. The virus has been found in dead birds in 54 California counties, including the surrounding counties of Marin, San Mateo, Alameda, Santa Clara and Contra Costa.

The announcement comes as no surprise to local health authorities who have been advising the public throughout the summer and into the City’s warmer fall weather to take precautions against mosquito bites that may carry the virus. Rajiv Bhatia, MD, Director of Occupational and Environmental Health observed, “While we have assumed that San Francisco residents are at risk of WNV, the bird deaths provide confirmatory evidence of West Nile Virus activity here in the City. We continue to urge everyone to be cautious, avoid areas where mosquitoes live and breed and report dead birds to the California West Nile Virus Hotline.” Last year, the first bird in San Francisco identified as having the West Nile Virus was discovered in late August.

San Francisco has had three cases of human West Nile Virus to date. Two of the patients were infected in the Sacramento area, and the most recent one contracted the disease in Wyoming. (The State of California does not count the out of state infection in its reporting data base.)

Over 40 San Francisco birds have been tested for the virus this year. Typically, WNV cases in birds precede human cases.

So far in 2005, 844 human cases of the West Nile virus have been reported from 39 California counties, with most of the cases in Sacramento and Riverside Counties. There have been 16 fatalities. In the United States, almost 10,000 human cases of WNV have been reported since it was first detected in the United States in New York in 1999.

Most individuals who become infected with WNV will not experience any illness. Others will have only mild symptoms, such as fever, fatigue, nausea, headache, muscle aches, skin rash, or swollen lymph nodes. However, WNV can affect the elderly and individuals with compromised immune systems with more severe illness.

WNV is transmitted to humans and animals through a mosquito bite. Mosquitoes become infected when they feed on infected birds. Human-to-human transmission of WNV does not occur.

San Francisco is taking several steps to limit risks to residents. The City’s mosquito control program includes: collecting birds for testing, monitoring ponds and other possible mosquito breeding sites, trapping to detect high numbers of mosquitoes, treating sewer catch basins to prevent breeding, and educating residents and owners about removing standing water from private property and avoiding mosquito bites.

Individuals can reduce their risk of mosquito-borne diseases by taking these precautions:

• Avoid spending time outside when mosquitoes are most active, especially at dawn and dusk.
• When outdoors, wear long pants and long-sleeved shirts.
• Apply insect repellent according to label instructions.
• Make sure that doors and windows have tight fitting screens. Repair or replace screens that have tears or holes.
• Eliminate all sources of standing water on your property that can support mosquito breeding.
• Contact the Department of Public Health, Mosquito Control program at 415-252-3806 if there is a significant mosquito problem where you live or work.

More information about West Nile Virus and San Francisco’s prevention activities can be found at the websites, http://www.sfmosquito.org, http://www.sfdph.org/eh/WestNile.htm and www.westnile.ca.gov.