See more of the story

Minnetonka schools are warning parents about cases of whooping cough that have popped up across the district.

Students at Minnetonka High School and Minnetonka Middle School West have been diagnosed with the bacterial illness also known as pertussis. A few isolated cases have also been reported at Excelsior Elementary and Clear Springs Elementary schools, a letter sent to district families and school staff said.

"It is important to note that most of these cases were diagnosed in students who were fully immunized," part of the letter reads. "While routine vaccinations do help to protect against pertussis, they are not foolproof. They can, however, reduce the severity and length of illness."

Pertussis can be serious, and may begin with a runny nose, sneezing, a mild cough and possibly a low-grade fever, the Minnesota Department of Health said. People with the illness should not go to work, school or any activities until they have finished five days of antibiotic treatment, the Health Department said.

Social distancing while infectious is very important to prevent the spread of pertussis, especially during ongoing outbreaks, the Health Department said.

"Now is a good time to make sure you are up to date on your pertussis vaccines," the department said.