Pertussis starts like a cold, but after a week or so, it leads to severe coughing fits that can take weeks to shake. It’s also called ‘whooping cough’ because patients make a high-pitched whoop sound as they suck in air.
There are 222 confirmed cases in the state this year, the highest levels since 2006.
"We are not blowing away records. Pertussis does tend to be cyclical, so you’ll see increases every 5 to ten years," says Beth Daly, Chief of Infectious Disease Surveillance at New Hampshire’s Health Department.
"So this is kind of an expected high. And it is certainly not as high as what some of the other states are reporting, like Vermont."
Vermont’s tally is 522, the highest number in decades. Maine is also seeing a jump in infections.
Daly says most people that get sick have been vaccinated.
Still, experts say vaccinations help slow the spread of whooping cough, and lower the number of severe cases.