Several people from across the US state of Illinois were tested for swine flu over the weekend, but the illness was ruled out in each case, Illinois' public health officials said on Monday.

So far, no one has been diagnosed with the type of flu that has resulted in deaths in Mexico and shown up in a milder form in several other U.S. states.

"This, however, is rapidly evolving situation, and we fully expect to see confirmed cases in Illinois at some time," said Dr. Damon T. Arnold, director of the Illinois Department of Public Health.

Sounding the same theme offered in Washington by President Obama Moday, Arnold cautioned people not to panic but to monitor the news and seek medical attention if symptoms go beyond the mildaches and sniffles of a typical flu.

During the weekend, he said, six of the cases submitted to laboratories for analysis came back as having nothing to do with the flu, and the seventh was determined to be a seasonal flu.

To avoid infection, Arnold urged people to wash their hands often and to avoid touching their eyes and noses if they are sick.

Also, the flu strain in question has an incubation period of about a week, so it's important for people who have traveled to areas with confirmed cases during that period to closely monitor their health, health officials said.