The number of reported pertussis cases in Calhoun County has risen to 11 since county health officials announced an outbreak earlier this month.

Health officials have confirmed nine of the cases of the disease, also known as whooping cough, and two are still probable, said Brigette Reichenbaugh, the health department’s operations and development manager.

The confirmed cases include a Pennfield Schools staff member and a student who were diagnosed with pertussis prior to the summer break, she said.

The district has posted a notice of a confirmed case on its website. Reichenbaugh said the two cases were confirmed on Monday.

“Yes, there are two confirmed cases of pertussis within the Pennfield school district,” she said. “We really recommend that people understand the symptoms of whooping cough.

“We really suggest vaccination,” she added, “and use caution if you think you have pertussis. It can be very serious in the very young.”