In Michigan, cases of whooping cough — pertussis — continue to climb

• Michigan reported 330 cases of pertussis by Saturday — three times the number in all of 2023
• To some extent, it’s a return to pre-pandemic levels
• Vaccine protection wanes, and the infection can be deadly for infants

Pertussis, an infection known for its can’t-catch-your-breath, whoop-like cough, continues its post-pandemic comeback.

As of last week, 333 cases had been detected statewide, according to data from the Michigan Department of Health and Human Services. The upward swing is a reflection of U.S. trends.

That’s already more than triple the cases for all of last year, according to reports compiled by MDHHS — and those numbers don’t yet reflect the school year and respiratory season just ahead.

Pertussis is caused by the bacterium Bordetella pertussis, which attaches to the lining of the upper respiratory system and releases toxins, causing the airways to swell and other damage, according to the Centers for Disease Control and Prevention. For many, the result is coughing fits with a "whoop" noise as they gasp for air. (Hear the distinctive cough here.)

“The violence of the cough in these children is really shocking,” said Dr. Jill Noble, director of the general pediatrics division at Ann Arbor-based Michigan Medicine. She remembers a child many years ago hospitalized with pertussis. 

Related:

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In between the coughing fits, that child was “normal, not really sick,” she said. But when the coughing started again, the child “would turn blue and would vomit. It was scary.”

The misery tends to linger, too — the reason some call it the “100-day cough.”

Most children are vaccinated against pertussis in what are known as the DTaP or TDaP vaccines, which also protect against diphtheria and tetanus. 

But protection is relatively short-lived compared to other vaccines. 

After the first year, vaccine protection against pertussis “waned rapidly so that little protection remained 2-3 years after vaccination,” according to a 2016 study published in the peer-reviewed journal, Pediatrics.

Still, getting the pertussis vaccine can help protect against its most severe symptoms, said Dr. Lea Monday, an infectious disease expert at Children’s Hospital of Michigan. That’s why it’s critical for pregnant people and a baby’s caregivers to be vaccinated, protecting newborns, whose immune systems are still developing, she said.

Experts recommend babies get a series of DTaP shots beginning at two months of age. A fifth dose is recommended through age 6 years.

“We need to change our perception,” Monday said. “The victory of the vaccine isn't ‘I didn't get pertussis.’ The victory is ‘My infant got pertussis, but she survived,’ or ‘My toddler got whooping cough because there was an outbreak… but he didn't die. He wasn't intubated.’”

In Michigan and across the country, cases of pertussis fluctuate wildly from year to year, with a 20-year high in Michigan of 1,363 cases during an outbreak in 2014, followed by 469 cases the following year. Remote school and work during the pandemic likely drove the numbers to lows of 74 in 2021 and 86 in 2022.

COVID-19, in fact, continues to disrupt the cyclical nature of many respiratory diseases, said Children’s Hospital’s Monday, so “it’s too soon to say” whether pertussis will continue its upward climb into the school year and respiratory season.

Cases began to inch upward earlier this year, and in June, Washtenaw County Health Department alerted the public and health providers about the uptick.

The goal was to pique awareness for doctors for whom pertussis is no longer top-of-mind, Susan Ringler-Cerniglia, health department spokesperson, told Bridge Michigan at the time.

The highly contagious respiratory illness can begin much like a common cold, according to the CDC. Early detection is important, so doctors can prompt antibiotic treatment, halting the spread to the state’s most vulnerable, Ringler-Cerniglia said.