West Nile Virus

West Nile Virus Activity

Confirmed Cases
in California
2009 YTD vs 2008 YTD

As of 7/16/09

Source:http://www.westnile.ca.gov
(2009 YTD-Year to date corresponds to the
same time last year)
2008 YTD 2009 YTD
# of Counties 49 31
Human Cases 445 0
Horses 32 0
Dead Birds 2569 169
Mosquito Samples 2003 120
Sentinal Chickens 585 5
Squirrels 32 1

What is West Nile Virus?

West Nile virus (WNV) is a potentially serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues into the fall. WNV season runs June 1-Nov. 1.

How WNV IS Spread to Humans?

WNV virus is transmitted to humans and animals through a mosquito bite. Mosquitos become infected when they feed on infected birds. Human-to-human transmission of WNV does not occur. However, human WNV infections have been associated with blood transfusions and organ transplants.

Control Activities in Alameda County

West Nile Virus was detected in 46 of California’s 58 counties (as of 11/08). During WNV season, Alameda County’s Mosquito Abatement program works to limit risks to residents by monitoring ponds and other possible mosquito breeding sites; trapping to detect high numbers of mosquitoes; treating sewer catch-basins to prevent breeding; collecting birds for testing; and educating residents and owners about removing standing water from private property to limit mosquito breeding and mosquito bites.