What Is Brucellosis? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Medically Reviewed

Brucellosis is an infectious disease caused by bacteria that spreads from animals to people.

You can catch brucellosis if you consume unpasteurized milk, cheese, or other dairy products from an infected animal.

While rare, it’s also possible to catch the disease through the air or through direct contact with infected animals.

Sheep, cattle, goats, pigs, and dogs are the animals most commonly infected with brucellosis.

Signs and Symptoms of Brucellosis

Symptoms of brucellosis can develop a few days to a few months after infection.

Brucellosis can cause a wide range of initial symptoms that are similar to the flu:

  • Fever
  • Sweats
  • Chills
  • Fatigue
  • Loss of appetite
  • Headache
  • Pain in muscles, joints, or the back
Some additional symptoms may last for longer periods of time, come and go, or may never go away:

  • Recurrent fever
  • Arthritis (joint inflammation)
  • Swelling of the scrotal area in men
  • Swelling of the heart
  • Swelling of the liver or spleen
  • Neurological symptoms
  • Chronic fatigue
  • Depression

Causes and Risk Factors of Brucellosis

Brucellosis is caused by the bacteria Brucella, which humans may contract from infected animals or contaminated animal products.

The most common ways humans contract the disease is by:

  • Eating raw dairy products contaminated by Brucella
  • Inhaling air contaminated by Brucella
  • Having an open wound and touching blood or body fluid of infected animals

The majority of brucellosis cases are caused by eating contaminated food products, such as:

  • Improperly pasteurized milk
  • Improperly pasteurized cheese
  • Raw meat
It’s important to make sure your milk is pasteurized to prevent transmission from cows and goats.

How Is Brucellosis Diagnosed?

Your doctor will confirm a diagnosis of brucellosis by running tests that look for the bacteria in samples of blood or other bodily fluids.

This often requires a biopsy of your liver tissue or bone marrow and the involvement of other medical specialists.

Another option is a blood test that detects antibodies against the bacteria that are released by your body.

If your doctor suspects you have complications due to brucellosis, they may order additional tests:

  • X-Rays This can help your doctor see changes in your bones and joints.
  • MRI or CT Scans Your doctor uses these to check for inflammation in the brain or other areas.
  • Echocardiography This image of your heart allows your doctor to check for signs of damage.
  • Cerebrospinal Fluid Analysis This test looks for infections like meningitis and encephalitis.

Duration of Brucellosis

Depending on the severity of the illness, recovery can take from a few weeks to a few months.

It’s necessary to take antibiotics for at least six weeks.

It’s possible for the disease to return and become chronic.

Treatment and Medication Options for Brucellosis

If you test positive for brucellosis, your doctor will most likely prescribe antibiotics.

The antibiotics doxycycline (Vibramycin) and rifampin (Rifadin) are often prescribed together for at least six to eight weeks.

Be sure to tell your doctor if you’re:

  • Pregnant
  • Allergic to doxycycline or rifampin
  • Immunosuppressed due to a drug or medical condition

Prevention of Brucellosis

Brucellosis is best prevented by avoiding undercooked meat and unpasteurized dairy products, including cheese, milk, and ice cream.

You can also reduce your risk by eliminating direct contact with cattle, goats, sheep, or pigs, or making sure that any animals you come into contact with are vaccinated against the disease. If you must handle animal tissues, protect yourself by wearing gloves and goggles.

Complications of Brucellosis

Left untreated, brucellosis can cause possible complications in organs throughout your body:

  • Endocarditis This is an infection of the heart’s inner lining. It is the leading cause of death due to brucellosis.
  • Arthritis You may experience pain, stiffness, and swelling in your knees, ankles, wrists, hips, and spine.
  • Inflammation of the Spleen and Liver This may be caused by an infection that causes the spleen and liver to become inflamed and enlarged.
  • Epididymo-orchitis This is inflammation and infection of the testicles, which can cause painful swelling.
  • Infections of the Central Nervous System These may include meningitis (inflammation of brain membranes) and encephalitis (inflammation of the brain itself), both of which can be life-threatening.

Research and Statistics: How Many People Have Brucellosis?

Men and women contract brucellosis at the same rate.

Brucellosis is rare in the United States, with less than 100 cases each year. This is because milk is routinely pasteurized and cattle are vaccinated.

Brucellosis is more common in other parts of the world, including Russia, Africa, South America, and the Middle East. These are places where livestock are not routinely vaccinated.

Related Conditions and Causes of Brucellosis

Food poisoning is similar to brucellosis — it can also result from eating unpasteurized dairy products and raw meat. Those foods can contain a number of harmful bacteria, including Campylobacter, E. coli, Listeria, and Salmonella, all of which can make you sick.

Brucellosis causes symptoms that are very similar to the flu, including fever, weakness, malaise, and weight loss. For this reason, it is important to see a doctor who can test for the Brucella bacteria to determine if you have brucellosis and not the flu.

Resources We Love

Centers for Disease Control and Prevention (CDC)

The CDC, a national public health institute, has detailed and up-to-date information on brucellosis and other infectious diseases. On its website, learn how to reduce your risk of brucellosis, plus potential treatment options.

National Organization for Rare Disorders (NORD)

NORD is a patient advocacy organization committed to the identification, treatment, and cure of rare diseases. Its website has further information on the symptoms, causes, and treatments for brucellosis.

Additional reporting by Cathy Cassata.

Editorial Sources and Fact-Checking

Show Less