Whooping cough, also known as pertussis, tends to come in waves and poses a quandary for infectious disease control experts, because it could have been eradicated.
Last year 1,183 cases were reported statewide, down slightly from 2012, when Utah's 1,544 whooping cough cases rivaled the pre-vaccination levels of the 1940s.
Nearly half-way into this year there have been more than 300 cases, including an outbreak at three schools in northern Utah. That investigation and the current one in central Utah started with hospitalized infants.
"That's why we want the adults and teens to get boosters, to keep these babies well," said Hilderbrand. The baby in central Utah had been at least partially immunized, she said.
Children entering school are required to be vaccinated against the disease with five doses of the DTaP vaccine, though some seek waivers. Entering seventh-graders must get a Tdap booster, which is also recommended for pregnant women and caretakers of infants.
Whooping cough is a respiratory infection characterized by severe coughing fits. Adults and adolescents may not even realize they have it, believing it to be a bad cold or cough.