The U.S. Centers for Disease Control and Prevention and state health officials are investigating potential exposures to Brucella strain RB51 (RB51) in 19 states, connected to consuming raw (unpasteurized) milk from Miller’s Biodiversity Farm in Quarryville, Pennsylvania. One case of RB51 infection (brucellosis) has been confirmed in New York, and an unknown number of people may have been exposed to RB51 from drinking the milk from this farm. This type of Brucella is resistant to first-line drugs and can be difficult to diagnose because of limited testing options and the fact that early brucellosis symptoms are similar to those of more common illnesses like flu.
The New York case is the third known instance of an infection with RB51 associated with consuming raw milk or raw milk products produced in the United States. The other two human cases occurred in October 2017 in New Jersey and in August 2017 in Texas. Those cases reported drinking raw milk from an online retailer and a Texas farm, respectively. In addition to these three confirmed cases, hundreds of others were potentially exposed to RB51 during these three incidents.
RB51 is a live, weakened strain used in a vaccine to protect cows against a more severe form of Brucella infection that can cause abortions in cows and severe illness in people. On rare occasions, cows vaccinated with RB51 vaccine can shed the bacteria in their milk. People who drink raw milk from cows that are shedding RB51 can develop brucellosis.
People who consumed raw milk or raw milk products from this dairy farm since January 2016 may have been exposed and should talk to their doctor.
People who are still within six months of the date they last consumed the raw milk are at an increased risk for brucellosis and should receive antibiotics to prevent an infection and symptoms, and should monitor their health for possible symptoms for six months. If symptoms develop, they should see their doctor immediately for testing.
Milk samples from Miller’s Biodiversity tested positive for RB51. A cow that tested positive for RB51 has been removed from the milking herd.