The Flathead City-County Health Department said Friday there now are 13 confirmed cases of whooping cough (pertussis) in the county, with more potential cases pending lab confirmation.

An additional ill elderly adult in the household of a confirmed case was diagnosed with pertussis but not tested.

Jody White, director of Community Health Services, said the number of pertussis cases includes:

 vThree students at Ruder Elementary School in Columbia Falls.

 vOne student at Glacier Gateway Elementary School in Columbia Falls.

vThree students at Swan River School.

v Four students at Kalispell Middle School

 Three adults (including one diagnosed but not tested).

Cases at Kalispell Middle School jumped from one confirmed Thursday to four confirmed by Friday.

A sixth-grade band and orchestra concert affected by the pertussis cases has been rescheduled for May 29, according to Kalispell Middle School Principal Barry Grace.

The concert had been planned for Thursday but was postponed on the recommendation of the health department.

White said the pertussis outbreak would not cancel all middle school events. The sixth-grade concert was postponed because the confirmed case Thursday was a sixth-grader and the concert was specific to the sixth grade.

According to White, the growing number of cases will require the health department to have staffers working today contacting people who have been exposed to whooping cough.

Health officials are telling them to go to their health-care provider for antibiotic medicine that costs between $20 and $30. The department has assistance for those who cannot afford the medicine.

White said the antibiotic does not cure pertussis but keeps the infected person from spreading the illness. She said people may return to work and students may return to school after five days on the antibiotic.

She said they may still have a cough but won’t be transmitting the disease.

In its latest press release, the health department urges anyone who has a cough that lasts more than a week to consult a health-care provider. Those with symptoms should stay home from school or work until they consult their health-care providers.

According to the Associated Press, state health officials say that as of Friday, Montana has 142 cases of whooping cough confirmed since Jan. 1.

Reporter Candace Chase may be reached at 758-4436 or by email at cchase@dailyinterlake.com.