Last Updated: April 18, 2006, 10:35:30 AM PDT

Stanislaus County health officials warned Monday that statewide outbreaks of "stomach flu" have hit the area, but said the virus can be controlled through good hygiene.

Dr. John Walker, the county's public health officer, said he's been "on the lookout" for cases here since the state's health department began alerting him of outbreaks over the past two months.

The stomach flu is transmitted by a norovirus, not the influenza virus, and usually lasts 24 to 48 hours with symptoms of nausea, vomiting and diarrhea, Walker said.

He said outbreaks were reported at several senior citizen facilities in the county, and he believes it also is affecting the general population.

Stomach flu is not a reportable disease, so the county does not keep statistics on the number of people affected.

"We wanted to alert the public, not to alarm them," Walker said. "We just really want to enforce good hygienic habits every opportunity we have."

Walker said he hopes the warning will prompt people to keep their living or workspace surfaces clean, as well as to make a habit of washing their hands or regularly using alcohol-based hand sanitizers.

Noroviruses are contagious. They are transmitted by touching contaminated surfaces and objects or through contaminated food or water, Walker said.

The greatest risk is dehydration, especially for young children, those with medical problems and the elderly, he said.

Bee staff writer Merrill Balassone can be reached at 578-2337 or mbalassone@modbee.com.