By Lorna Benson, MPR.org/90.1 FM

ROCHESTER — Health officials are investigating a pertussis cluster in southeastern Minnesota.

Since May 16, Olmsted County has reported 31 cases of the bacterial infection, also known as whooping cough. Most are teenagers in the Rochester School District.

“In the past two weeks that’s been a lot of cases to have,” says Victor Cruz, an epidemiologist at the Minnesota Department of Health.

Statewide there have been 237 confirmed, probable and suspected cases of pertussis this year. Olmstead County has had a total of 42.

Local public health workers are following up with all cases in the county and their contacts.

“So they’re working really hard on controlling the outbreak and making sure that everyone is getting both the treatment they need and go in for testing,” says Cruz.

Pertussis causes severe coughing that can lead to vomiting and even cracked ribs. The distinctive whooping sound people make gave rise to the common name. The disease can be especially severe in young children, and sometimes is fatal.

The infection is treated with a course of antibiotics. If given early in the illness, the medication can lessen symptoms somewhat. But coughing spells can linger for months. It’s important to get antibiotic treatment anyway to reduce the chance of spreading the disease.

“We just recommend individuals who are infectious exclude themselves from activities and be treated to prevent further spread and also to protect the community,” says Cruz.

Significant pertussis outbreaks typically occur every three to five years. Four years ago Minnesota had it’s largest outbreak ever recorded since a vaccine became available. There were 4,144 cases in 2012.

Early childhood pertussis vaccinations weaken during adolescence and that is one factor behind a nationwide resurgence of the disease.