At least 18 people have now been sickened in an outbreak of Campylobacter infection associated with raw milk from a cow-share farm in Alaska’s Matanuska-Susitna (Mat-Su) Valley, according to an updated epidemiology bulletin from the state Department of Health and Social Services.
The Alaskan outbreak, first reported in late June, is ongoing and remains a threat to consumers, the June 28 update states.
Four people were initially reported to be sick with campylobacteriosis; the 18 now affected include seven lab-confirmed cases and 11 suspected cases.
Laboratory results combined with the epidemiological finding that raw milk consumption from the same dairy (identified as “Farm A”) is the only exposure common to all the cases “confirms the conclusion that this outbreak is due to consumption of Farm A raw dairy products,” the bulletin states.
Campylobacter jejuni bacteria isolated in manure samples from the grazing field and in the calf barn matched the bacteria isolated from the seven laboratory-confirmed patients, as identified by pulsed-field gel electrophoresis (PFGE), the health department said.
Milk samples from the bulk tank, collected on June 22 and 27, tested negative for Campylobacter but positive for Listeria monocytogenes, the bulletin reported. None of the raw milk actually consumed by the ill persons was available for testing.
“It is not surprising that C. jejuni was not detected in Farm A bulk tank samples because C. jejuni is notoriously difficult to culture from environmental specimens other than raw stool, and few campylobacteriosis outbreak investigations yield laboratory confirmation of an implicated food source such as raw milk or produce,” the Alaska public health officials wrote.
“Contamination might have resulted from introduction of manure into the milk or cream at some point in time from milking to filling the containers, or a cow (or cows) with an infected udder may be intermittently shedding Campylobacter directly into the milk,” the bulletin added. “Regardless of the exact mechanism of contamination, with confirmed cases reporting consumption of dairy products over an 8-week period from May to July, this outbreak poses an ongoing threat to Farm A raw dairy product consumers.”
Alaska state law does not permit the sale of unpasteurized milk, but does allow owning shares of an animal to obtain raw milk — which does not have to be tested before it is distributed, an Alaska Department of Health and Social Services (DHSS) spokesman said in an earlier news release.