On February 13, 2013, Alaska State Public Health Laboratory (ASPHL) notified the Alaska Section of Epidemiology (SOE) of a cluster of four Campylobacter coli isolates with an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern that was new to Alaska. All four isolates were grown from stool specimens collected in late January from ill Kenai Peninsula residents.

Patient interviews and other investigative work indicated that all four of the ill persons with PFGE-matching C. coli strains reported consuming raw (unpasteurized) milk within a few days of their illness onset. These initial interviews also led to additional case finding, primarily by way of ill persons reporting others they knew who were also ill with similar symptoms. While some of the persons who were initially identified during this investigation were reluctant to say where their raw milk came from, four individuals reported that it came from Farm A (Peninsula Dairy), a cow-share farm on the Kenai Peninsula.

A confirmed case was defined as a laboratory-confirmed, PFGE-matched, C. coli infection diagnosed from January 1, 2013 onward. A clinical case was defined as an acute GI illness with self-reported diarrhea lasting ≥2 days in a person with exposure to Farm A raw milk within 10 days of illness onset. A secondary case was defined as an acute GI illness lasting ≥2 days in a person with close contact to a confirmed or clinical case within 10 days of illness onset.

On February 14, SOE notified the Office of the State Veterinarian (OSV) of the outbreak, and a joint press release and health advisory were issued on February 15.2 OSV immediately notified Farm A of the outbreak and requested a list of all active shareholders. Despite notification of the outbreak, Farm A (Peninsula Dairy) continued to distribute raw milk to shareholders living in the Kenai Peninsula and in Anchorage.

During the week of February 18, two additional confirmed cases were reported—one of which was in a school-aged child who was hospitalized for 4 days with fevers, abdominal pain, rash, and acute reactive arthritis involving the wrists, ankles, knees, and hips. On February 22, an updated health advisory describing new developments in the outbreak was issued.3 On February 22, Farm A provided SOE with an incomplete shareholder list, which lacked contact information for the majority of shareholders. Calls were made to notify persons on the list about the outbreak and to identify additional cases.

In total, 31 cases were identified during the investigation. Ill persons ranged in age from 7 months to 72 years (median: 10 years). Three children and one adult developed reactive arthritis lasting a minimum of 6 weeks. Two persons were hospitalized. All ill persons were Kenai Peninsula residents who either personally consumed Farm A (Peninsula Dairy)raw milk within 10 days of illness onset (n=29) or met the secondary case definition (n=2).