CDC Probing Suspect Raw Milk at Pennsylvania Dairy

Katlyn Brinkley

March 07, 2019

Federal health officials are investigating a possible case of exposure to bacteria from raw milk sold at a farm in Pennsylvania.

The investigation comes after a New York resident became sick in November. The patient drank raw milk purchased from Miller's Biodiversity Farm in Quarryville, Pennsylvania, and was later diagnosed with brucellosis.

The milk tested positive for Brucella, the bacteria that cause brucellosis. This is only the third known case of brucellosis in the United States in the past 2 years. Brucella bacteria are passed on from animals to people through raw dairy. Raw dairy products are not pasteurized, which kills dangerous bacteria.

The CDC has warned the public not to eat or drink the unpasteurized products and recommends throwing away products from Miller's Biodiversity Farm in Quarryville. The state of Pennsylvania quarantined the farm in December and banned sales of dairy products made from raw cow's milk.

The company did not respond to repeated requests for comment.

Brucellosis Gone Viral

As of January 22, people in 19 states had bought or consumed raw milk from Miller's Biodiversity Farm, according to the CDC. Officials recommend that anyone who has consumed raw dairy since January 2016 watch out for symptoms. Eating or drinking unpasteurized dairy products is the most common way to get the disease in the United States.

During pasteurization, milk is heated to kill dangerous bacteria that cause foodborne illnesses. Pasteurization was created when bacterial foodborne illnesses, such as typhoid fever, were spreading rapidly, often causing death. Removing germs from food prevents deadly diseases like these from resurfacing, as well as reduces more common foodborne illnesses today, such as salmonella or E. coli.

"Treating brucellosis early is easier, but when it becomes chronic is when it is difficult to treat," says Lee Riley, MD, a professor of epidemiology and head of the infectious diseases division at the University of California, Berkeley. Riley says at chronic stages, as is the case with other severe illnesses, health professionals often can only treat a patient's symptoms.


Brucellosis can be difficult to identify at first because symptoms are similar to the flu. Early signs of the infection include:

  • Fever

  • Sweats

  • Loss of appetite

  • Headache

  • Fatigue

  • Muscle and joint pain

When the disease is more serious, it can last a long time and cause inflammation or infection of joints and organs. At that stage, the bacteria are resistant to some treatments.

People who are most likely to get brucellosis are those with weakened immune systems, such as infants, older adults and pregnant women, as well as people who work with animals. People who have been exposed to contaminated raw milk less than 6 months ago are also at higher risk and should become familiar with brucellosis symptoms to look for signs of infection.

If symptoms of brucellosis appear and it has been longer than 6 months since the last exposure to contaminated raw milk, get a blood test from your doctor.

The Raw Milk Myth

People may choose to drink raw milk because they believe nutrients are lost during pasteurization and natural enzymes in raw milk kill bacteria, but there is little evidence to back up these claims, the CDC says.

"That's an absolutely wrong idea that [raw milk] is more nutritious," Riley says. "It has all of the risks and no benefits."

Raw Regulation

Even though less than 1% of the population drinks raw milk and most research advises against it, more than half of US states allow the sale of raw dairy products.

The sale of raw milk is legal in 30 states in the US, and the states, not the FDA, regulate it. Officials with the American Academy of Pediatrics, the FDA, and the CDC agree that the lack of benefits and presence of risks from these products are significant.

Marion Nestle, Paulette Goddard professor and professor emerita of nutrition and food studies at New York University, says public pressure is the main reason it is still legal to sell unpasteurized milk.

"This is a complicated issue that requires nuanced understanding of the issues," she says.

"Raw milk is risky, but it's hard to say how risky. That always makes these kinds of issues difficult to deal with."

CORRECTION: A previous version of this story included incorrect information about when the suspect raw milk was purchased. The purchases were all made before January 22.


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