Skip to content

Mosquito biting skin

Contra Costa County woman recovering from West Nile

on September 26, 2011

A 49-year-old East Contra Costa County woman is recovering after being hospitalized from the first confirmed case of West Nile Virus in the county this year. And although no cases have been reported in Richmond, the weekend’s rainfall has likely created additional breeding areas for the insects, and residents should be on alert, according to health officials.

“Every year is different, and we can’t predict West Nile activity because of weather, because of how much water we get—it’s just very dynamic,” said Deborah Bass, public affairs manager for Contra Costa Mosquito & Vector Control District. “But some areas received rain over the weekend—certainly in West County—and that’s likely to increase standing water around the home.”

West Nile Virus is a disease that is spread to humans who are bit by a mosquito that’s carrying the virus, Bass said. Mosquitoes reproduce the virus in their salivary glands after feeding on an infected bird. In warm weather, the virus reproduces more quickly.

But the summer heat came later this year, and as warm temperatures drag into the rainy season, health officials are keeping a close eye on how that weather system will affect humans in Contra Costa County, Bass said.

“We had a very cool summer, and that was beneficial in terms of mosquito production,” Bass said. “But now it’s hotter, so they go through their lives quicker and numbers are higher.”

West Nile Virus reared its head in the United States on the East Coast in 1999, and gained more attention in 2002, when 24 people died from the disease, according to the Centers for Disease Control.

It traveled west and appeared in Contra Costa County in 2005, said Erika Jenssen, communicable disease programs manager for Contra Costa County Health Services. That year, nine cases were confirmed, and the number per year has been four or five since then. Two deaths occurred in the county in 2006, but Jenssen was unable to confirm how many of those cases affected Richmond residents.

California is number one so far this year with 48 confirmed cases reported, according to the CDC. Closest behind is Mississippi with 33 confirmed cases, but most cases nationwide go unreported.

To reduce mosquito breeding, county health officials encourage homeowners to eliminate standing water outdoors, where the insects can go from larvae to “biting adult” in as little as five days, Bass said.

“For the most part, they breed in neglected swimming pools,” Bass said, adding that there are 23 kinds of mosquitoes in Contra Costa County, some of which carry the virus, and some of which don’t. “But they also—and many people don’t realize this—breed in flower pots with residual water, which are good for breeding because of all those nutrients.”

For this reason, residents are encouraged to dump any water around the home at least twice a week, she said.

Across the board, about 80 percent of individuals who come down with the virus don’t know they’re infected, and the other 20 or so see a doctor and receive treatment based on their immune system, Jenssen said.

“Most of the time, people don’t know that they are infected with West Nile Virus, or that they recovered,” she said. “Most people recover quite quickly from it—they may have no symptoms, or they may feel bad for just a little while.”

Symptoms of the virus include fever, headache, body aches and swollen lymph nodes, Jenssen said. More severe and less common symptoms include confusion, paralysis and potentially permanent neurological effects.

The county’s Mosquito & Vector control offers free mosquito fish available to residents who cannot maintain their pools but want to reduce the number of mosquitoes. Visit for more information.

For more information on West Nile Virus in Contra Costa County, visit



Richmond Confidential welcomes comments from our readers, but we ask users to keep all discussion civil and on-topic. Comments post automatically without review from our staff, but we reserve the right to delete material that is libelous, a personal attack, or spam. We request that commenters consistently use the same login name. Comments from the same user posted under multiple aliases may be deleted. Richmond Confidential assumes no liability for comments posted to the site and no endorsement is implied; commenters are solely responsible for their own content.

Card image cap
Richmond Confidential

Richmond Confidential is an online news service produced by the UC Berkeley Graduate School of Journalism for, and about, the people of Richmond, California. Our goal is to produce professional and engaging journalism that is useful for the citizens of the city.

Please send news tips to

Latest Posts

Scroll To Top