Food poisoning that made more than 50 teachers and staff members at Roosevelt High School sick, prompting classes and many activities to be canceled Oct. 22, was caused by a bacteria in meat purchased and served to staff, a report found.

The Polk County Health Department released an investigation summary Wednesday that points to the bacteria Clostridium perfringens, which the CDC says causes more than 1 million cases of food poisoning a year.

The bacteria is among the most common causes of food poisoning. It’s often found in poultry, gravies and dried or pre-cooked foods.

Cooking kills the bacteria, but does not necessarily kill its spores. If not properly refrigerated, meat that contained the bacteria can grow and produce new cells, the report says. It can grow quickly at room temperature but not at colder temperatures in a refrigerator or freezer.

The report did not include information about the origins of the food that contained the bacteria, and department spokeswoman Nola Aigner cited state law in not disclosing the kind of meat or where it was purchased from.

“I can’t reveal that due to our public health confidentiality laws, I can’t discuss the specific details of the case,” she said.

That sucks. How are others supposed to learn?