SPOKANE, Wash. - Spokane Public Schools officials said students at three local schools may have been exposed to pertussis, or whooping cough.

The district sent out a health alert over email on Thursday night warning parents of students at Browne Elementary, Glover Middle and Shadle Park High School that their children may have been exposed. Spokane Public Schools spokesman Brian Coddington said the affected students are now out of school.

"We had three known cases of pertussis. They're siblings, they go to these three different schools," Coddington said.

Coddington said the students were probably in school for about a week before being diagnosed.

The Spokane Regional Health District said 15 cases of pertussis have been reported in Spokane County since October 1, 2019. Eleven of those cases involve students. Spokane Regional Health District epidemiologist Mark Springer said whooping cough doesn't really have a season, but they see more cases when school is in session.

"This is hitting really all parts of the county... and it's something we want to encourage parents to look out for," Springer said.

The Health District said symptoms can start out looking like a mild cold, especially in older children. Parents are advised to watch for coughing that lasts more than two weeks, vomiting breathlessness after a coughing fit and a whooping sound when coughing. The Health District said young children might even turn blue after coughing.

Springer encouraged parents to take their children to the doctor if they exhibit any of those symptoms.

"The best thing you can do if your child has pertussis is to keep your child home until they've been on the antibiotics for five days," Springer said. "At that point, they're no longer infectious."

Spokane Public Schools officials said there was a communication error that happened around the time the pertussis email went out. All families in the district received a phone call in Arabic about early release for elementary students. The district says that call had nothing to do with a health alert.

Spokane Public Schools said the only schools affected by the pertussis alert as of Friday are Browne Elementary, Glover Middle and Shadle Park High.