March 11, 2026
Wyoming Department of Health (WDH) officials are concerned about the ongoing, active spread of pertussis (whooping cough) across the state.
Kaylyn Friesen, vaccine-preventable disease epidemiologist with WDH, said there have been 26 confirmed pertussis cases in Wyoming so far this year. “While roughly two-thirds of the reported cases have been among Fremont County residents, pertussis has also been identified in other counties,” Friesen said.
Friesen noted that 148 cases were reported in Wyoming in 2025, the highest since 1951. “We are continuing to see outbreaks and high monthly case counts,” Friesen said.
Actual case numbers are likely higher because many illnesses are not recognized as pertussis, and others may not be reported. Pertussis typically begins with cold-like symptoms and perhaps a mild cough. Pertussis is often not suspected or diagnosed until a persistent cough with spasms develops after 1 to 2 weeks. Infants and children can cough violently and rapidly with a loud “whooping” sound.
Dr. Alexia Harrist, state health officer with WDH, said, “One-third of infants less than 1 year of age who become ill with pertussis need to be hospitalized, and we know, in some cases, it can be deadly for these babies. Pertussis in the youngest babies can cause them to have pauses in breathing. Infants are simply more vulnerable and don’t yet have all the protection pertussis vaccines offer.”
Harrist said the Tdap adolescent/adult pertussis booster vaccine is especially important for those spending time with new infants, such as parents, grandparents, and other people who take care of them. “Also, if you are pregnant or planning on becoming pregnant, you should talk to your doctor about a Tdap vaccine because that can also help protect newborns,” she said.
Harrist recommends that all residents stay up to date with pertussis vaccines, as those who still become ill with pertussis after vaccination are less likely to have a severe experience. “In addition, people should consider seeing a medical professional for antibiotics if they have symptoms consistent with pertussis,” she said.
More information about pertussis can be found online at https://health.wyo.gov/publichealth/infectious-disease-epidemiology-unit/disease/pertussis/.
