Pathogens prevalent in unpasteurized milk

By Scott Baltic

NEW YORK (Reuters Health) - A survey of unpasteurized milk samples drawn from dairy farms across Wisconsin found a significant presence of Coxiella burnetii and Listeria monocytogenes, two different types of bacteria that can cause serious infection and even death in some people.

These findings have particular relevance for consumers seeking raw milk products.

The study, reported at the annual International Conference on Diseases in Nature Communicable to Man held last week in Madison, Wisconsin, was based on a random sampling of milk from 901 Wisconsin dairy farms. The farms were chosen to encompass small and large herds, producers of Grade A and B milk, and all five of the state's geographic regions.

Approximately 76 percent of the samples had detectable C. burnetii DNA, and 5 percent of the samples harbored L. monocytogenes.

Milk from larger herds and farms producing Grade A milk appeared to have a larger risk of having detectable C. burnetii, but no clear risk factors emerged to predict which farms were more likely to have L. monocytogenes in their milk. Both bacteria were broadly distributed geographically.

Presenter Dr. Suzanne Gibbons-Burgener, from the University of Wisconsin in Madison, noted that on-farm use of raw milk is legal and common, and that the sale of unpasteurized milk is legal in 28 states, though California, for example, requires a warning label.

In some states that ban the sale of raw milk, including Wisconsin, advocates of what they call Real Milk have over the past 10 years organized "Cow-Share" programs. Under these programs, consumers who want unpasteurized dairy products circumvent such bans by buying shares in a cow or herd.

A poster presentation at the meeting by the Public Health Agency of Canada reported an outbreak of Campylobacter infection in Ontario in June that was traced to cheese made at a local farm from unpasteurized milk. About two dozen people became ill and eight sought medical help.