The Montana Department of Health has reported (pdf) that as of November 15, 2012, a whooping cough (Bordetella pertussis) outbreak has reached over 500 cases since the beginning of the year, compared to only 129 cases during the same time period in 2011. As of November 15, 33 cases of pertussis were found in infants of less than one year of age. Of these, four have been hospitalized. Because Montana is has a small population (about 1 million people), the overall incidence rate year to date is 50.5 pertussis cases per 100,000 Montana residents.
This past spring, there was a pertussis outbreak in several Montana counties, but it seemed to abate during the summer. The Department of Health is reporting that Flathead county, a northern county that borders Canada, is currently struggling to contain an outbreak in five school districts. “Since the beginning of October, we have 35 cases,” said Community Health Services Director for Flathead County Jody White. “Usually we won’t even see 35 in a year, so it is definitely unusual to have this many.”