It’s not even halfway through the year, and Arizona is already on track to see the highest number of annual whooping cough cases in a decade.

Whooping cough, or pertussis, caseloads began surging nationwide in 2024 and have been rising even higher so far in 2025. The Arizona Department of Health Services has reported 464 probable and confirmed cases of pertussis as of mid-May, which is an 80% increase compared to the same time last year.

On average for the last five years, the state has reported only about 331 cases annually.

Dr. Joshua Sharfstein, a pediatrician and professor of the practice at the Johns Hopkins University School of Public Health, said the virus is most dangerous for small babies, who are too young to be vaccinated.

“It is just awful. Children are suffering terribly, they’re gasping for breath, they have trouble bringing in air, and their parents are suffering terribly watching them,” Sharfstein said.

Sharfstein said family members or anyone who has contact with infants should take extra precautions.

“People should be vaccinated and you should be vigilant about coughs for all the people who are around a small baby,” Sharfstein said.

The Centers for Disease Control and Prevention recommends infants and children under 7 years old receive routine vaccinations against whooping cough. Adults should get vaccinated every 10 years as part of the Tdap booster, which also protects against tetanus and diphtheria. The CDC also recommends women get the Tdap shot during the third trimester of every pregnancy to help protect babies from whooping cough in the first few months of life.

The pertussis vaccination rate among Arizona kindergarteners has been falling, according to the ADHS. About 89% were vaccinated last year, compared to about 95% a decade earlier.