CONTRA COSTA COUNTY (BCN) — Five dead birds and a sentinel chicken were added to the list of the animals that have tested positive for West Nile Virus in Contra Costa County, officials with the Contra Costa County Mosquito & Vector Control District confirmed.
The birds were found in Antioch, Alamo, Brentwood, Concord and Orinda and the chicken was in a coop in the Holland Tract near Knightsen, an unincorporated community in Contra Costa County.
This year in Contra Costa County 12 birds, three chickens and mosquitoes from four samples tested positive for the virus, Contra Costa County Mosquito & Vector Control District spokeswoman Deborah Bass said.
Those numbers reflect a typical non-drought year in the county, Bass said.
Most of the positive tests have occurred in the northeastern part of the county, according to the district’s website.
This year in California one person has died. That person was a resident of Sacramento County.
Nine other people in California have tested positive for the disease, but none of those people are residents of the Bay Area.
Since 2005, 55 Contra Costa County residents have tested positive for the disease and two residents died of the disease in 2006.
Backyard sources of water are a huge problem for officials trying to control the mosquito population and transmission of the disease, Bass said. Mosquitoes breed in water so any standing water can be a source of more mosquitoes.
Neglected swimming pools can be the biggest source because one neglected pool can be a breeding ground for more than a million mosquitoes, which can affect people five miles away.
Bass said even though no one in the county has tested positive for West Nile Virus, it’s important to reduce areas of standing water.
For every person who tests positive, 70 people will get a milder form of the disease called West Nile Fever, which causes flu-like symptoms that can keep a person home from work.
Bass said the virus extracts a high cost on society.
A 2005 outbreak among 163 people in Sacramento County cost an estimated $2.98 million. Scientists estimated that preventing just 15 cases of the severe form of disease would be equal or greater than the cost of conducting an emergency mosquito spray.