Health officials are warning about an increase in whooping cough cases. There have been hundreds this year in Minnesota and Wisconsin.

“Cases have definitely increased compared to last year,” said Victor Cruz, a senior epidemiologist with the Minnesota Department of Health.

As of September 12, there have been 708 cases of pertussis in Minnesota, according to MDH. Last year there were 61.

“It’s highly infectious and spreads mainly through the cough,” said Cruz.

Infants under 12 months old are at the highest risk of severe complications, according to Cruz. There have been cases among all ages of children and adults.

“One of the difficulties with pertussis is early on, symptoms can seem pretty non-descript,” said Cruz. “Feeling tired, having a cough, maybe even some sneezing, but after the first week or two weeks, that’s when the coughing gets really, really bad.”

He explained symptoms can include coughing so hard it’s difficult to catch your breath or throwing up.

Pertussis is spreading in Wisconsin as well. The state’s Department of Health Services this week is urging parents to make sure their children are up to date on their vaccine.

DHS reports 625 confirmed cases this year compared to 51 in 2023. Two-thirds of the counties in the state have reported at least one case, according to the state agency.

“Cases of pertussis do tend to cycle every three to five years,” said Cruz, who explained there’s currently an upcycle.

The last time cases were this high in Minnesota was in 2017, when there were 734 cases. There were roughly 600 to 1,000 cases every year between 2013 and 2017, according to state data. Cases plummeted after the pandemic. According to the CDC, nationwide, it appears cases of pertussis are returning “to more typical trends.”

“It’s really important that we identify the cases early, get them tested and any appropriate treatments they need,” said Cruz.