Friday, Sep. 25, 2009

West Nile virus returns

Stanislaus County is tied for most cases in state

After it seemed like a light year for West Nile virus, the disease has returned in full force in the past three weeks in Stanislaus County.

As of Friday, Stanislaus and Kern counties, each with 11 reported cases, had the most cases this year among the 41 counties in California affected by West Nile.

Stanislaus health officials reported 10 of the cases this month, the patients ranging in age from 27 to 84. All of the patients were stricken with neuroinvasive West Nile disease, a debilitating form of the illness that can result in long-term neurological symptoms.

Surveillance personnel with local mosquito abatement districts still are finding infected mosquitoes in the field. Positive mosquito samples prompted the Turlock Mosquito Abatement District to conduct aerial spraying over 5,000 acres along the edge of west Turlock last week.

"It hit in the latter part of August and has just been building with more and more activity in the last three weeks," said Jerry Davis, manager of the Turlock district.

With the unseasonably warm temperatures, officials expect the virus will make one last assault in the early weeks of fall and then go into dormancy as the weather cools.

Six of the people stricken this year live in the Turlock area, with most coming down with symptoms the last week in August and first week in September. The latest cases in the county were reported to the state Monday and Tuesday, a 53-year-old woman and 41-year-old man, both with neurological symptoms.

"We talked to a number of people who had to be hospitalized," Davis said. "A number of them didn't recall being bitten by mosquitoes. People should avoid being outdoors near sunset or sunrise, and if they can't avoid it they should use insect repellant."

The West Nile disease, which is native to Africa and first detected in the United States in 1999, hasn't bitten very hard in California this year. As of Friday, the state had 62 cases of infection and two deaths, compared with 445 people infected and 15 fatalities last year.

The two deaths this year were in Merced and Fresno counties. The fatality is Merced County's only confirmed case this year; San Joaquin County has reported five people infected.

Close to 90 positive mosquito samples have been reported in Stanislaus County, the second-highest since the virus first surfaced in the county in 2004. Stanislaus County reported 18 people infected in 2008.

County officials said there were few signs of the virus during the not-so-hot first half of the summer. West Nile tends to thrive in hotter conditions, so it is still a threat with temperatures forecast in the high 90s this weekend.

About one in five people infected with West Nile will have symptoms such as fever, body aches, nausea, vomiting or swollen lymph glands. The symptoms may last for a few days to several weeks.

One in 150 of those infected suffer a debilitating attack to their nervous systems, accompanied by fever, neck stiffness, disorientation, coma, tremors and paralysis. This form of the illness can be fatal or cause permanent neurological effects.

People planning a barbecue or picnic this weekend should be aware of mosquitoes. A species that carries the virus moves into residential areas as cornfields and other crops are harvested this time of year, said Lloyd Douglass, general manager of the East Side Mosquito Abatement District, which is responsible for mosquito control in and around Modesto and other communities north of the Tuolumne River.

The mosquitoes gather around homes and can get into a house through an open window or hole in a screen door.

Bee staff writer Ken Carlson can be reached at kcarlson@modbee.com or 578-2321.