[INTERACTIVE MAP: Map and timeline of swine flu cases]
State public health officials say more than one case is being sent to federal authorities for confirmation.
The Illinois Department of Public Health has conducted tests on patient specimens showing swine flu is probable.
State public health spokeswoman Melaney Arnold says the federal Centers for Disease Control and Prevention will make the final determination on whether Illinois' cases matches the swine flu outbreak in Mexico.
She says one case is located at a school on Chicago's north side. The school is closed today.
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