The number of patients believed infected with the contagious form of A/H1N1 flu in the US Illinois State rose to 54 this morning, with three confirmed cases, the Illinois Department of Public Health said on Friday.

The confirmed cases are the state's first since the outbreak began, although the threshold for probables involves testing that is 99 percent certain, according to health officials.

Chicago has the highest number of cases of any jurisdiction in the state, with 15 probable and two confirmed cases. As of this morning, there are 11 probables and one confirmed in DuPage County, about 45 kilometers west of Chicago, and 11 probables in suburban Cook County, about 25 kilometers south of Chicago.

For the first time, Kendall County, about 100 kilometers southwest of Chicago, was added to the list of counties with flu cases, with one probable case, according to the state's health officials.

Meanwhile, suburban schools in Cook and surrounding counties announced closings after several students appeared to show signs of the virus.

And in Illinois, the only patient hospitalized from the suspected flu, a 12-year-old Chicago girl who is a student at an elementary school, returned home from the hospital and was recovering, health officials said.

Hospitals in the Chicago area began screening emergency room walk-ins for flu symptoms.

Medical officials said the current strain of flu, while certainly highly contagious because of its novelty and lack of built-up immunity, did not seem to compare with earlier, infamous flu outbreaks.

(Xinhua News Agency May 2, 2009)