Sharing Milk but Not Messages: Campylobacteriosis Associated with Consumption of Raw Milk from a Cow-Share Program in Alaska

Contamination might have resulted from introduction of manure into the milk or cream at some point between milking and filling the containers

Alaska public and environmental health authorities investigated a cluster of campylobacteriosis cases among people who had consumed raw, unpasteurized milk obtained from a cow-share program in Alaska.

Although raw milk is not permitted by law to be offered commercially, consumers can enter into cow-share agreements whereby they contribute funds for the upkeep of cows and in turn receive a share of the milk for their personal use.

Laboratory testing of stool specimens collected from ill persons and from cows on the farm revealed an indistinguishable strain of Campylobacter jejuni.

In this outbreak, numerous confirmed and suspected cases were not among cow shareholders; therefore, these individuals had not been advised of the potential health hazards associated with consumption of raw milk nor were they informed of the outbreak developments.

Of the 13 farm sampled, 7 were positive for Campylobacter; six of the cultures grew C. jejuni, one sample grew a Campylobacter species that was not further identified, and another grew both C. jejuni and the unidentified Campylobacter species. In total, 22 separate C. jejuni colonies were confirmed and subtyped by PFGE; seven unique combined SmaI-KpnI PFGE patterns were identified. Combined PFGE pattern AKDBRS16.0166/AKDBRK02.0093 was found in isolates from manure samples from the grazing field and the calf barn; this combined pattern was indistinguishable from the combined SmaI-KpnI PFGE pattern of C. jejuni isolated from the seven laboratory-confirmed cases.

The identical rare strain of C. jejuni was detected in all laboratory-confirmed cases associated with this outbreak and in farm A cow manure specimens. These laboratory findings combined with the epidemiologic finding that farm A raw dairy product consumption was the only exposure common to all seven laboratory-confirmed cases (and the 11 suspect cases) supported the conclusion that this outbreak resulted from consumption of raw dairy products from farm A. Contamination might have resulted from introduction of manure into the milk or cream at some point between milking and filling the containers. Alternatively, a cow (or cows) with an infected udder may have been intermittently shedding Campylobacter directly into the milk.

Source: L. J. Castrodale et al. Journal of Food Protection May 2013

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