brucellosis

What You Need to Know


  • Brucellosis is a disease caused by Brucella bacteria that come from infected animals and can be found in unpasteurized (raw) dairy products, like raw milk and cheese.

  • Most people get brucellosis by eating or drinking unpasteurized dairy products made from the milk of infected cows and goats.

  • You can prevent brucellosis by avoiding unpasteurized milk and cheese (including queso fresco made from raw milk) and eating only dairy products that state on the label that they are pasteurized.


Various dairy products, including sour cream, butter, cheese, and milk

What is brucellosis?

Brucellosis is a disease caused by infection with Brucella bacteria that come from farm animals (cows, goats, sheep, pigs), some wild animals (wild pigs, camels, bison), and rarely pet dogs. Brucellosis is found throughout the world but is most common in areas that do not have animal health programs designed to control Brucella infection in animals. Brucellosis is not as common in the United States, but cases are reported each year in California.

Dairy cow and goat

Farm animals (cows and goats), some wild animals, and rarely pet dogs can be infected with Brucella bacteria. There are different types of Brucella that infect different types of animals. Animals get infected from other animals and may be unable to reproduce if they are infected for a long time.

How do people get  brucellosis?

People can get brucellosis in the following ways:

  • More commonly by eating or drinking unpasteurized (raw) dairy products, such as milk, cheese, and ice cream, that come from infected animals​

    • ​​This includes eating queso fresco, queso cotija, and other soft cheeses made from raw milk​

  • Less commonly from contact with infected animals, when bacteria from infected animal tissues or fluids get into the body through the eyes, nose, or mouth or through a break in the skin​​

    • ​​​​This includes eating undercooked meat and breathing bacteria in closed spaces where ​infected animals or animal tissues are present

Who can get brucellosis?

Anyone who eats or drinks raw milk or other unpasteurized dairy products is at risk for getting brucellosis.

  • Ranchers, veterinarians, and slaughterhouse workers may be more likely to get brucellosis because their jobs involve contact with animals and animal tissues that could be infected with Brucella.

  • Hunters and other people who handle tissues or meat from wild pigs may also be at risk for infection with the type of Brucella that infects wild pigs (called Brucella suis).

  • There are also rare infections among laboratory workers who work with Brucella bacteria in the lab.


In California, brucellosis is more common among Hispanic/Latino men. A 25-year (1993–2017) study showed that many people with brucellosis in California reported getting the dairy products that made them sick from outside the United States, most commonly from Mexico.

What are the symptoms of brucellosis?

The symptoms of brucellosis are similar to those of many other illnesses and usually include: Person holding their head in pain, and another person clutching their back in pain

      • Fever
      • Sweats
      • General feeling of being unwell (malaise)
      • Headache
      • Back pain

It usually takes 1–6 weeks from the time a person is exposed (such as by eating unpasteurized dairy products) to the start of symptoms, but it can take as long as several months for symptoms to appear.

​​Because the symptoms of brucellosis are like those of other common diseases, a healthcare provider may need to order specific lab tests to see if a person is infected with Brucella. Tests for brucellosis may include taking a blood sample to test for infection.

Death from brucellosis is rare, but if brucellosis is not properly treated, infection can spread to the bones, joints, liver, kidney, spleen, or heart months to years later. Brucellosis can be treated with antibiotics, but antibiotics often must continue for several weeks or months to fully treat the infection. 

How can I help prevent brucellosis?

The best way to prevent brucellosis is to not eat or drink dairy products that have not been pasteurized. Pasteurization is the process of heating dairy products to kill harmful germs that can make people sick. Check the label of any dairy product before buying it and eat only dairy products that state on the label that they are pasteurized. If you are not sure if a dairy product is pasteurized, do not eat it. Cheese or other dairy products that are not packaged and clearly labeled as “pasteurized” may not be safe to eat because they could contain harmful germs that could make you sick.

Choose pasteruized milk

    Choose cheese made with pasteurized milk

People who touch or handle animal tissues (such as hunters or people who work in slaughterhouses) should protect themselves and cover their skin, eyes, nose, and mouth by wearing rubber gloves, goggles, and gowns or aprons to help prevent contact with Brucella bacteria.

Resources​

Information for the Public​
Information for Human Health Professionals
Information for Animal Health Professionals
Information for Local Health Departments ​
  Data & Statistics
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