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Minnesota's first infant death from whooping cough in six years has prompted state health officials to warn the public about the bacterial infection and the need to protect newborns through maternal vaccination.

The infant died in November after being diagnosed with whooping cough, or pertussis, in August and hospitalized for three months, the Minnesota Department of Health announced Wednesday.

"Pertussis continues to be a concern in Minnesota, and we want to do everything we can to prevent future tragedies like this," said Kristen Ehresmann, the Health Department's infectious disease director.

Once more common in the summer months, pertussis is now a year-round risk that peaks in Minnesota every three to five years.

The state recorded 555 cases of pertussis last year, down from 1,247 cases in 2016. Health officials suspect 2020 could be a peak year. Ehresmann said the number of annual cases has been trending upward and the peak years have been getting worse.

"It's sort of like an escalating roller coaster," she said. "With each peak, we are seeing more disease."

While anyone with pertussis can suffer respiratory and cold symptoms — including the gasping-for-breath cough that inspired its nickname — infants are most at risk of severe consequences and prolonged hospitalizations. Of the 25 cases last year involving babies younger than 6 months, eight resulted in hospitalizations.

Maternal vaccination is recommended because newborns are otherwise unprotected until they receive the DTaP vaccine (short for diphtheria, tetanus and acellular pertussis) at 2 months of age. When mothers are vaccinated during pregnancy, they produce antibodies that pass along to their newborns in the womb and help protect them, Ehresmann said.

It appears, however, that some mothers are hesitant to receive booster shots. State health officials reviewed 41 infant pertussis cases in Minnesota over the last two years and found that just 44% of the mothers had been vaccinated during pregnancy.

"We're missing opportunities to vaccinate during pregnancy and protect vulnerable infants," Ehresmann said.

The pertussis booster is known as Tdap and is recommended for expecting mothers in their third trimesters. It's also recommended for adolescents — in part to protect them from infections and in part to protect younger siblings or infants to whom they could spread the bacteria. Studies have found that infants are generally infected by older siblings, parents or other caregivers who often don't know they have whooping cough because their symptoms are less severe.

Pertussis typically spreads when infected people cough or sneeze. It usually begins with coldlike symptoms such as a runny nose, low-grade fever and a mild cough, but can develop into coughing fits, vomiting and extreme fatigue.

Health officials declined to provide specifics about the infant who died, noting that the family is grieving over the loss of a newborn.

Jeremy Olson • 612-673-7744