Outpatient health care visits for flu-like illnesses are at their highest levels in 15 years, according to data updated Friday by the CDC.

The Centers for Disease Control and Prevention lists Illinois in the high category for flu cases, and across the Chicago area, emergency department visits, hospital admissions, and ICU admissions for the flu are currently higher than the peak of last season.

The map of flu activity across the United States continues to darken, both figuratively and literally, as case numbers spike upward in most states, according to the Centers for Disease Control and Prevention (CDC).

Testing results from patients indicate that two strains of seasonal flu that are causing most illnesses — a Type A H1N1 and a Type A H3N2. Health officials are closely watching