FALMOUTH, Maine (AP) Maine’s status as the state with the highest rate of whooping cough in the country is worsening, due to an uptick in the number of cases of the disease this year.

The bacterial infection also known as pertussis results in a violent, hacking cough. Maine’s rate of the disease is eight times the national average, and there were nearly 450 cases last year.

The Portland Press Herald reports there were 95 cases of the disease through February, and that’s more than double the count from 2018.

University of New England professor Meghan May, who researches pertussis, says more vaccinated people are getting the disease because the bacterium that causes it has mutated.

The Maine Center for Disease Control & Prevention’s looking into the uptick.