The number of Flathead Valley cases of pertussis (whooping cough) climbed to 25 Tuesday with more cases at Kalispell Middle School and new cases at Evergreen Middle School, Trinity Lutheran School and two unspecified rural schools.

Flathead City-County Health Officer Joe Russell said the 19 cases reported Monday afternoon grew before the day was out. Late-arriving lab results diagnosed new pertussis illness in two sixth-graders and an eighth-grader.

“We had a new eighth-grader as of this morning,” Russell said on Tuesday.

More Kalispell Middle School positive lab tests brought a new notice to parents from Principal Barry Grace.

The four cases at the school Friday have grown to eight with three more sixth-graders and now one eighth-grader.

“If you are considering having your student take the antibiotic for this, then it would be advisable to perhaps carry through with that,” Grace said in the email to parents.

One of the new positive lab results was from a middle school-aged student in Bigfork Elementary/Middle School. Russell said the youth had no symptoms of pertussis.

“We’re not too concerned about an asymptomatic kid because they have to have some way of transmitting it,” he said. “They have to be sneezing or coughing.”

He said the student has begun a course of antibiotics.

According to Russell, the department had talked to families of sixth-graders at Kalispell Middle School but now is working on contacting families of eighth graders who were exposed and need to take antibiotics. He said the Trinity Lutheran student had only a few contacts with other students and all of them had been covered.

The Evergreen Middle School case is a different story. “The Evergreen case we’re just rolling on right now,” Russell said. “The Evergreen one is about 100 contacts and every one of those has to be called.”

With pertussis spreading, health department staffers from many divisions have pitched in to make telephone calls. Russell said he expects to make calls, too, to give some people a break.

“We’re going to keep plugging away at it,” he said. “They’re getting a little tired but we’re doing okay.”

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