Flathead County’s confirmed cases of pertussis (whooping cough) reached 53 on Tuesday with the results of the latest tests conducted by the laboratory at Kalispell Regional Medical Center.

Jody White, director of the Community Health Division of the Flathead City-County Health Department, said the new positive cases did not add any new schools to the list of those with confirmed cases of pertussis.

“We just have one of the same schools with a different grade,” White said.

The confirmed case of a fifth-grader at Hedges Elementary School means the health department staff must conduct a new round of calls to parents of exposed children who may have been infected.

They ask that exposed children and adults take a course of antibiotics so they don’t spread the illness.

White said the next weeks will show whether people have followed through to obtain and take the antibiotic. Since pertussis has an average incubation period of six to 12  days, children and a few adults exposed recently soon would test positive as secondary cases.

“This week and the next week will be telltale weeks,” she said.

White said the lab had 40 tests to run Tuesday morning. Results from 30 of those raised the number to 53 with at least 10 test results still pending.

With case counts updated on May 25, the Montana Department of Health and Human Services reported 246 pertussis cases statewide.

Ravalli County had with 53 cases and Flathead County 51 cases at that time. Flathead had the most new cases with 47 in the last three weeks followed by Rosebud with 18 cases and the most cases per 100,000 people.

The state health department counted 18 jurisdictions with 246 people infected compared to 56 cases for the same period in 2011.

Vaccine for pertussis remains available for those 2 months of age and older.

The health department has additional information at 751-8110.