alaskapublic.org reports the Alaska State Department of Health is investigating an outbreak of a foodborne illness linked to raw milk. Officials have confirmed four cases of Campylobacter infection in people who drank raw milk on the Kenai Peninsula.

Dr. Brian Yablon is a medical epidemiologist with the state. He says the cases have all been identified by the state lab in the last three weeks:

“When they looked at these strains, they found that the four specimens were all exactly the same type, so that is consistent with a cluster of illnesses and when we found out additional information it seemed that all of the people who developed the infection had consumed raw milk or unpasteurized milk in the proceeding several days before they got sick,” Yablon said.

The state is still working to identify the source of the raw milk. A farmer named Kevin Byers in Kasilof distributes raw milk to families around the state. He did not agree to a recorded interview, but said he doesn’t know if his milk is responsible for the outbreak. He says his customers drink his milk for the perceived health benefits. According to a recent newspaper article, Byers has 150 customers as far away as Sitka.

Selling raw milk is illegal in Alaska. But farmers have found ways to do it legally.

A similar outbreak of Campylobacter bacteria was traced to a Mat-Su Valley farmer in 2011. There were 18 people with probable or confirmed illness in that outbreak. That operation has since gone out of business.