MONTGOMERY, Ala. (AP) — The Alabama Department of Public Health has identified an outbreak of whooping cough in Shelby and Jefferson counties.

Health officials said Friday that nine children testified positive for pertussis, also known as whooping cough. Another 22 people have developed symptoms.

Pertussis is a highly contagious respiratory disease. It begins with a runny nose and low grade fever but develops into a violent cough.

Health officials identified a number of churches and camps where the infected people attended in June and July.

The number of pertussis cases is on the rise in Alabama. There were 151 reported cases in 2017. There have been 172 reported cases so far in 2018.