PHILADELPHIA — Health officials confirmed Pennsylvania's first case of swine flu Sunday in a 31-year-old man in suburban Philadelphia's Montgomery County.

Gov. Ed Rendell told reporters at a late afternoon news conference that the man had recently arrived from Mexico but had recovered.

State health officials said they are investigating seven more probable cases of the illness, including the first outside of the Philadelphia area — two cases in Philadelphia, two cases in Montgomery County and one each in Bucks County, Lycoming and Luzerne counties.

Pennsylvania Health Secretary Everette James urged residents to remain calm and said officials are taking every possible step to prevent the spread of the virus, including deploying antiviral drugs to treat confirmed or probable cases of the disease.

"So far, most cases have been relatively mild and treatable with antivirals," he said in a statement.

Authorities are urging commonsense precautions such as washing hands frequently, covering the face when coughing or sneezing and staying home in the event of illness to avoid infecting others.