The flu season may have arrived.

Flu activity isn't yet widespread, but new case reports have been on the uptick for the past couple of weeks in Pennsylvania, said Richard McGarvey, spokesman for the state Department of Health.

Most of that activity had been in Eastern Pennsylvania, specifically the Philadelphia-Allentown area. But Allegheny County officials yesterday noted nine new influenza cases have been confirmed here in the last two weeks.

"Up until a week ago or so, we really weren't seeing anything you'd call the flu," said Dr. Raymond Pitetti, an emergency physician at Children's Hospital. But more children with respiratory diseases have been seen in the last couple of weeks, he said, including a number with classic flu symptoms.

"It's definitely on the upswing, but it's still nowhere near where we were last year," said Guillermo Cole, spokesman for the Allegheny County Health Department.

The county reported its first confirmed case on Oct. 20, suggesting the season was getting an early start. But, until recently, additional cases were few and far between.

The county now has 23 suspected or confirmed cases of the flu, which compares with the 21 suspected or confirmed cases it had by mid-December of 2004 and the 129 cases it had at this point in January 2005.

"This is by no means the worst of it," Mr. Cole added, suggesting the peak may come sometime in the next four to six weeks if previous flu seasons are a guide.

Though Western Pennsylvania has lagged behind the east in the number of cases thus far, confirmed cases in the state now total 157, "which is about right for this time of year," Mr. McGarvey said.

By the end of the last flu season, 940 suspected or confirmed flu cases had been reported in Allegheny County, a record number. The increased use of instant flu tests in doctor's offices has helped boost flu case reports in recent years, though they are classified only as "suspected" cases because the state requires a laboratory test before a case is considered "confirmed." Last year, 545 of the county's cases were in the suspected category.

The U.S. Centers for Disease Control and Prevention last Saturday warned that two antiviral drugs that can prevent or reduce the duration of type A influenza infections should not be used this season. Laboratory tests show that this season's prevalent type A strains are developing significant resistance to both rimantadine and amantadine.

Thus far, of the 23 suspected or confirmed cases in Allegheny County, 14 are type A flu. But Mr. Cole said the recommendation against the use of rimantadine and amantadine is unlikely to have much impact.

"It's our perception that [those drugs] are not widely used anymore," he said, noting that the antiviral drugs Tamiflu and Relenza, which are effective against both types A and B, are the most popular of the antiviral prescription drugs.

Treatment with any antiviral must begin within 24 to 48 hours of the onset of flu symptoms if they are to lessen the severity of the disease.

More than 77 million doses of flu vaccine had been distributed nationwide by the end of November, the CDC reports, and more than 80 million doses are expected to be administered by the end of the season.

Though some doctor's offices and clinics had trouble obtaining vaccine this season, the total number of doses was enough to meet the past consumer demand for vaccine, which usually is about 70 to 75 million doses. Anxiety about the "bird flu" (which the current flu vaccine does not prevent) may have spurred demand this season, the CDC said, and one manufacturer, Chiron Corp., had production problems that forced it deliver fewer doses than it had projected.

Even without vaccines or antiviral drugs, people can reduce their risk of the flu and the risk of others by regularly washing their hands with soap and water or alcohol-based hand sanitizers. People should avoid touching their eyes, nose or mouth -- common entry points for the virus.

Those who have the flu -- an upper respiratory disease marked by rapid onset of fever, chills, headache, cough, sore throat and extreme fatigue -- should keep their distance from others and stay home from work or school to prevent the infection from spreading.