Health officials say the swine flu virus is still lurking around the Northern San Joaquin Valley, giving rise to isolated cases, but they are most concerned about possible outbreaks in the fall.
On Monday, health officials reported the first confirmed case in Stanislaus County, a 22-year-old woman who became ill on June 3.
Dr. John Walker, county public health officer, said the woman was sick for a week and was treated as an outpatient. A sample taken by her health care provider tested positive for the H1N1 virus.
The woman had no contact with Mexico, where the initial outbreaks were reported earlier this year, Walker said. Officials are not aware of any cases related to hers.
The woman's name and city of residence were not released.
"It is my opinion this virus is circulating in all parts of Stanislaus County," Walker said. He urged people to take precautions such as washing their hands frequently, using hand sanitizer and covering coughs with their sleeves or tissues.
The H1N1 virus appears to thrive in cold, moist environments. Among the hundreds of samples sent to labs for testing, the county had one other probable case of swine flu, but it turned out to be a false positive, Walker said.
In California, health agencies have reported 918 confirmed cases of the novel flu and are awaiting lab results on 203 probable cases. Seventy-six people have been hospitalized in the state, and six of the 45 swine flu deaths in the United States have occurred in California.
San Joaquin County has reported 10 confirmed cases, three probable cases and three people who required hospitalization; Merced County has two reported cases.
With more than 70 countries reporting swine flu, the World Health Organization announced last week that a global pandemic was under way. The virus has not been especially virulent, but it has acted like most common types of influenza, spreading easily and causing mild symptoms such as fever, cough, sore throat, body aches, chills and fatigue.
Most people who have been hospitalized already were suffering from persistent health problems, though some who have died had no history of chronic illness. The United States usually averages 36,000 deaths per year from seasonal influenza.
Health experts in the United States are watching countries in the Southern Hemisphere, where the flu season is about to take hold, for signs of how the H1N1 virus could behave when the fall 2009 flu season begins here.
"It will probably give us a forecast of what we can expect," Walker said. "As a public health agency, we hope for the best, but plan for the worst."
Bee staff writer Ken Carlson can be reached at firstname.lastname@example.org or 578-2321.