The Alaska Department of Health and Social Services is investigating four cases of people who became sick after drinking bacteria-contaminated raw milk from a Mat-Su Valley farm.

According to DHSS spokesperson Greg Wilkinson, state law doesn’t allow the sale of raw milk, but does permit owning shares of an animal to receive its milk — which doesn’t have to be tested or pasteurized before it’s distributed.

The four people infected with Campylobacter jejuni bacteria from May 7 through June 4 were Southcentral Alaska residents ranging in age from 1 to 81 years old. All four experienced severe stomach flu after drinking raw milk from one of the unnamed farm’s cows, and two said family members also experienced symptoms but did not seek medical attention.

Staff with the state Department of Conservation’s Division of Environmental Health visited the farm in May to evaluate sanitary conditions and pick up a bulk milk tank for testing. The sample tested negative for Campylobacter but positive for Listeria monocytogenes, a foodborne pathogen that can cause life-threatening infections in newborns and adults.

Officials believe the month-long pattern of cases points to a series of contamination events rather than a single bad batch, which is possible given the rich nutrients contained in milk.

“Raw milk is an ideal substance for the proliferation of bacteria introduced through fecal contamination,” said Dr. Joe McLaughlin, chief of the DHSS Section of Epidemiology. “Unpasteurized milk can be infected with a number of pathogens including Listeria, Salmonella, and as we’ve seen in this case, Campylobacter.”

A fact sheet on Listeria was distributed to the 1,100 shareholders in the farm’s cow-share program following DEC’s May visit. Test results from a June 22 follow-up visit by DEC and DHSS personnel are still pending.