Influenza cases have risen sharply across southeast Michigan, as a particularly aggressive strain of the influenza virus takes a toll on schools, nursing homes and health care facilities.

According to a report by the Michigan Department of Health and Human Services Weekly released Monday, influenza activity in the state is considered widespread with “535 positive influenza-related hospitalizations (30 pediatric and 505 adults)” since Oct. 1.

Of the 318 cases testing positive for influenza by the MDHHS Bureau of Laboratories, 245 were confirmed to be the particularly aggressive H3N2, also known as Type A. Many people don’t actually get tested for the flu so the actual number of cases is much larger.

The report also showed that among the 195 reported cases of viral respiratory illness outbreaks, the majority — 138 — happened in long-term care/assisted living facilities, 25 in K-12 schools/colleges and 23 in health care facilities.