Raw Milk Associated with Brucella abortus Outbreak


Brucella abortus strain RB51 is implicated in outbreaks of brucellosis in consumers of raw milk in New Jersey, Texas and New York. Brucellosis is a difficult disease to diagnose and patients presenting with recurrent fever are frequently not tested for the infection. Primary care physicians do not generally include brucellosis in a differential diagnosis, the disease having been virtually eliminated in the U.S. as a result of the almost universal application of pasteurization.

Strain RB51 was licensed as a B. abortus vaccine in 1996 and is administered by an accredited veterinarian. The use of this vaccine has declined during the past decade as brucellosis has been almost completely eradicated in commercial herds. Calves receiving the vaccine are identified with a vaccination ear tag and tattoo on the right ear. Since RB51 vaccine is derived from the pathogen, it is possible that by inappropriate administration or persistent infection, the live vaccine strain may contaminate milk. Pasteurization will destroy this vaccine strain rendering milk innocuous. Consumption of raw milk carries the risk of tuberculosis, salmonellosis, listeriosis, STEC, campylobacteriosis and now more recently brucellosis.