Illinois grapples with whooping cough cases after US saw massive 2024 spike
As of early May, Illinois has already reported more whooping cough cases than the state typically sees in an entire calendar year.
The U.S. as a whole is struggling similarly with the “very infectious” disease. U.S. Center for Disease Control and Prevention data show the nation has recorded twice as many whooping cough cases so far in 2025 compared to the same time period last year, Dr. Vidya Sundareshan, infectious diseases specialist at Southern Illinois University Medicine and medical advisor to Sangamon County Health Department, wrote in a May 16 email to the News-Democrat.
According to a provisional report from the CDC, 35,435 pertussis cases were reported across the nation in 2024, resulting in 10 deaths. Four people older than one died, while six infants younger than one died.
The case count in 2024 represented a huge increase in whooping cough compared to previous years — 2023 saw 7,063 cases in the U.S., and 2024’s count was also higher than pre-pandemic figures. The last time the U.S. reported more whooping cough cases than 2024’s count was 2012. Before that, the case count had not been so high since 1959.
So far, CDC data is indicating 2025 could be an even worse year for pertussis in the U.S., Sundareshan said. Declining vaccination rates put “more people at risk,” she continued.
Illinois reported 2,584 pertussis cases in 2024, according to preliminary data from the state health department, and 327 cases have been reported for 2025 so far as of April 26.
The metro-east has also seen an increase in pertussis cases recently, according to data from the state health department.
St. Clair County has reported two pertussis cases this year as of May 9, according to data shared with the News-Democrat via email by St. Clair County Health Department spokesperson Brenda Fedak. The county reported 21 cases in 2024, three in 2023, one in 2022 and two in 2019.
The Illinois Department of Public Health reports the metro-east region as a whole has reported 19 pertussis cases so far in 2025 as of May 6, and reported 99 total in 2024, 14 in 2023, five in 2022 and two in 2021.
What is whooping cough, or pertussis?
Whooping cough and pertussis are used interchangeably to refer to the same “very contagious” respiratory illness. Pertussis may feel like a common cold at first, but the coughing can last much longer, according to the CDC.
Pertussis is a respiratory illness caused by a bacteria called Bordetella pertussis, the CDC reports, and it’s only found in humans. It typically takes five to 10 days for symptoms to begin after exposure to the bacteria, but can take as long as three weeks to appear.
Early pertussis symptoms can last for one to two weeks, according to the CDC, and often include a runny or stuffed-up nose, low-grade fever and a mild, occasional cough.
“Healthcare providers often don’t suspect or diagnose it until more severe symptoms appear,” the CDC website reads.
Around one to two weeks after the first symptoms start, people with pertussis may develop coughing fits, also called paroxysms. The fits usually last one to six weeks, but can persist for up to 10 weeks, and the coughing generally gets worse as the illness progresses.
“Those who get these coughing fits say it’s the worst cough of their lives,” the CDC website reads.
Pertussis is also called “whooping cough” because when people inhale after a coughing fit they sometimes make a high pitched “whoop” sound, the CDC says. The coughing fits can lead to vomiting.
The third and final stage of pertussis is called the “convalescent” stage and can take weeks to months to fully resolve, Sundareshan said.
Young infants are most at risk of serious complications from pertussis, but older children and adults can also require hospitalization. Infants younger than one year old who get pertussis have about a 33% chance of needing treatment in a hospital, Sundareshan said, and hospitalization is most common for infants under six months of age.
“Death is uncommon but may occur with serious complications that are more often seen in people who are not vaccinated,” Sundareshan added.
Pertussis complications can include dehydration, nose bleeds, ear infections, lack of appetite, pneumonia, hernias, passing out and urinary incontinence from the cough, Sundareshan said.
More serious complications, especially for infants, can include an inability to breathe, inflammation of the brain from lack of oxygen from coughing or directly from the infection, severe pneumonia, rupture of the lung, rib fracture, brain hematoma and seizures from violent coughing, Sundareshan said.
Do you need a pertussis vaccine?
The CDC recommends pertussis vaccines for infants, children, adolescents and pregnant people, as well as adults who didn’t receive one as a child.
In the U.S., protection against pertussis is administered in two types of combination vaccines: DTaP and Tdap, which both also protect against diphtheria and tetanus. Children younger than 7 years of age receive DTaP, and those older than 7 get the Tdap vaccine.
The CDC recommends children receive a five-dose series of DTaP vaccines, with one at two months of age, one at four months, one at six months, one between the age of 15 and 18 months and another at four to six years old.
Additionally, children age 11 to 12 should receive a single dose of Tdap, federal health officials advise. Pregnant people are advised to get a single dose of Tdap, preferably between gestation weeks 27 to 36.
Adults who have never received a Tdap vaccine should get a single dose, the CDC says. There is no recommendation for booster doses, although pertussis immunity wanes after a few years.
“Adults do need booster doses every 10 years to maintain protection against tetanus and diphtheria,” the CDC website says. “Although these doses are aimed to protect against diphtheria and tetanus, healthcare providers can administer either Td or Tdap.”
Unvaccinated or undervaccinated infants younger than 12 months of age are at the highest risk of severe complications and death from pertussis, Sundareshan said. Vaccinating against pertussis is “very effective,” she added.
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