PHOENIX — Arizona is experiencing its highest number of whooping cough cases in more than a decade, with health experts pointing to declining vaccination rates as a key factor behind the surge.
The state recorded nearly 1,000 whooping cough cases in 2025 — twice the five-year average and the highest number in 12 years, according to data from the Arizona Department of Health Services. In 2013, there were 1,440 cases. In 2025, data show there were 992 cases. So far in 2026, there have already been 43 cases reported.
"Whooping cough, we are seeing numbers that are greater than what we've seen," said Dr. Vasu Bhavaraju, a pediatric hospitalist and chief medical education officer at Phoenix Children's Hospital.
The illness, also known as pertussis, is highly contagious and spreads through infected droplets from the nose and mouth, Bhavaraju said.
Bhavaraju attributes the increase to declining vaccination rates across the state. The vaccination exemption rate for kindergarten students has been growing over the years. In the 2018-2019 school year, 5.9% of kindergartners had a personal exemption. In the 2024-2025 school year, 9% of kindergartners had that same exemption.
“Unfortunately, what we're seeing with the decline in vaccination rates, we are seeing more pertussis," Bhavaraju said. "It is a preventable disease. We have a vaccine that is well studied, safe and effective."
Schools are also dealing with whooping cough cases. According to Jackie Duarte, the nurse coordinator for Deer Valley Unified School District, the district must notify families when there’s exposure to certain students.
"The Maricopa County Department of Health will notify us because there's a protocol placed there where they will let us know who that student was and that it was positive for that," Duarte said. "And then they typically also will send out letters of guidance and letters that we can share with parents or any of those that we feel have been exposed."
The district maintains evening cleaning protocols and relies on families to report when their children are sick, Duarte said.
With respiratory illness season continuing and flu, COVID-19 and RSV still circulating, health officials are urging families to take precautions.
"Hands are the number one way that germs get transmitted from one person to the next. And so, we do encourage them to wash frequently," Duarte said.
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