State health officials said the number of reported cases of whooping cough more than tripled in Maine this year. There have been 701 cases so far in 2012, compared to 202 in the previous year. The number of cases nationally also hit a more than 50-year high. Whooping cough, also known as pertussis, is a respiratory disease characterized by long, violent coughing fits. State epidemiologist Stephen Sears told the Portland Press Herald that residents should get vaccinated if they are not sure about their immunization history.