Brucellosis is an infection caused by bacteria. It spreads from animals to people. Most often, people get brucellosis by eating dairy products that are raw or not treated to make them safer, called pasteurization. In certain workplaces the bacteria that cause brucellosis can be inhaled. People can also get brucellosis through direct contact with infected animals.

Symptoms of brucellosis may include fever, joint pain and being very tired. The infection can often be treated with antibiotics. However, treatment takes several weeks to months. And the infection can come back.

Brucellosis affects many people and animals around the world. Not eating or drinking raw dairy products helps prevent brucellosis. Being careful when working with animals, animal processing or in a laboratory can help prevent brucellosis.

Symptoms of brucellosis may show up anytime from a few days to a few months after infection. Symptoms are like those of the flu. They include:

• Fever.
• Chills.
• Loss of appetite.
• Heavy sweating.
• Weakness.
• Tiredness.
• Joint, muscle and back pain.
• Headache.

Brucellosis symptoms may disappear for weeks or months and then return. Some people have long-term, called chronic, brucellosis. They have symptoms for years, even after treatment. Long-term symptoms may include:

• Tiredness.
• Repeated fevers.
• Swelling, called inflammation, of the inner lining of the heart chambers, called endocarditis.
• Joint inflammation, called arthritis.
• Arthritis of the spinal bones, called spondylitis.
• Arthritis of joints where the spine and pelvis connect, called sacroiliitis.

Brucellosis can be hard to diagnose, especially in the early stages. At that point, it often seems like other conditions, such as the flu. Make a medical appointment if you are at risk for brucellosis and you have a fever that goes up fast or lasts, or muscle aches or unusual weakness.

Brucellosis bacteria are carried by many animals. The bacteria may or may not cause animals to be sick. Some that carry bacteria that can infect humans, include:

• Cattle, goats and sheep.
• Pigs and wild hogs.
• Dogs, especially those used in hunting.
• Deer, elk, caribou and moose.
• Bison.
• Camels.

A form of brucellosis also affects harbor seals, porpoises and certain whales.

The most common ways that bacteria spread from animals to people are by:

• Eating raw animal products. Brucella bacteria in the milk of infected animals can spread to humans unpasteurized, milk, ice cream, butter and cheeses. The bacteria can also come from raw or undercooked meat of infected animals.
• Breathing in bacteria. Brucella bacteria spread easily in the air. Farmers, hunters, laboratory workers and slaughterhouse workers can breathe in the bacteria.
• Touching blood and body fluids of infected animals. Bacteria in the blood, semen or placenta of an infected animal can enter a person's blood through a cut or other wound. Contact with animals, such as touching, brushing or playing with them, doesn't cause infection. So people rarely get brucellosis from their pets. Even so, people who have weakened immune systems should avoid touching dogs that have the disease.

Brucellosis isn't likely to spread from person to person. But rarely, the disease can be passed during birth or through breast milk. Rarely, brucellosis may spread through sexual activity or through infected blood or bone marrow transfusions.

Brucellosis is rare in the United States. But it's more common in other parts of the world, especially:

• Southern Europe, including Portugal, Spain, Turkey, Italy, Greece, Southern France.
• Eastern Europe.
• Mexico, South and Central America.
• Asia.
• Africa.
• The Caribbean.
• The Middle East.

Jobs at higher risk

People who work with animals or who come into contact with infected blood are at higher risk of brucellosis. Examples include:

• Veterinarians.
• Dairy farmers.
• Ranchers.
• Slaughterhouse workers.
• Hunters.
• Microbiologists.

Brucellosis can affect almost any part of the body, including the reproductive system, liver, heart and central nervous system. Long-term, called chronic, brucellosis may cause complications in just one organ or through the body. Possible complications include:

• Swelling, called inflammation, of the inner lining of the heart chambers, called endocarditis. This is one of the most serious complications of brucellosis. Untreated endocarditis can damage or destroy the heart valves. This is the main cause of death from brucellosis.
• Arthritis. This is marked by pain, stiffness and swelling in the joints, especially the knees, hips, ankles, wrists and spine. Arthritis of the joints in the spine, called spondylitis, and the joints linking the lower spine and pelvis, called sacroiliitis, can be hard to treat. They may cause lasting damage.
• Infection of the testicles, called epididymo-orchitis. The bacteria that cause brucellosis can infect the coiled tube above and behind the testicles that stores and transports sperm, called the epididymis. The infection can spread to the testicle. This causes swelling and pain, which may be severe.
• Infection of the spleen and liver. Brucellosis can also affect the spleen and liver, causing them to get larger than usual.
• Central nervous system infections. These include possibly life-threatening illnesses such as swelling, called inflammation, of the membranes around the brain and spinal cord, called meningitis, or of the brain, called encephalitis.

To reduce the risk of getting brucellosis, take these precautions:

• Don't eat dairy foods that haven't been treated, called pasteurized. In recent years in the United States, few cases of brucellosis have been linked to raw dairy products from domestic herds. Still, it's best to avoid unpasteurized milk, cheese and ice cream, no matter where they come from. If you're traveling to other countries, avoid all raw dairy foods.
• Cook meat all the way. Cook a whole cut of meat until it reaches an inside temperature of 145 Fahrenheit (63 Celsius). Let it sit for at least three minutes before cutting or eating. It will be medium done. Cook ground meat to 160 F (71 C). That's well done. Cook poultry, including ground poultry, to 165 F (74 C). Don't eat undercooked meats.
• Wear gloves. If you're a veterinarian, farmer, hunter or slaughterhouse worker, wear rubber gloves when handling sick or dead animals or animal tissue. Wear gloves when helping an animal give birth.
• Take care in high-risk workplaces. For laboratory work, make sure all biosafety conditions are being met. Slaughterhouses should also take protective measures. These include wearing protective clothing and having the killing floor apart from other work areas.
• Vaccinate farm animals. In the United States, brucellosis in livestock is rare due to vaccination. Because the brucellosis vaccine is live, people who get stuck by a needle while vaccinating animals can get the disease. They need to be treated.

Diagnosis of brucellosis is made by testing blood or the spongy matter inside the bones, called bone marrow. Other tests can help find complications of brucellosis. They include:

• X-rays. X-rays can show changes in the bones and joints.
• CT scan or MRI scan. These imaging tests can show areas of the brain or other tissues that might be affected by brucellosis.
• Cerebrospinal fluid culture. This checks a small sample of the fluid that surrounds your brain and spinal cord for infections such as meningitis and encephalitis.
• Echocardiography. This test uses sound waves to make pictures of the heart to check for signs of infection or damage to the heart.

Treatment for brucellosis is to relieve symptoms, prevent the disease from coming back and prevent complications. Treatment involves taking antibiotics for at least six weeks. Symptoms may not go away completely for several months. The disease also may return and become long-term, called chronic.

You may start by seeing your healthcare professional. Then, you may be referred to an infectious disease specialist. A diagnosis of brucellosis depends on your coming into contact with the bacteria that cause the disease. Your healthcare team will need as much information as possible about that.

What you can do

Before your appointment, you may want to write down the answers to the following questions:

• When did you begin having symptoms?
• Have you had any raw dairy products, such as milk or goat cheese?
• Does your job involve contact with animals or with animal tissues?
• Have you traveled to countries other than the United States during the past year?
• Do you work in a lab where infectious bacteria are present?
• Have you gone hunting recently?

What to expect from your doctor

During the physical exam, your healthcare professional may:

• Ask you to move your joints, to check for pain and stiffness.
• Check your reflexes and the strength of your muscles.
• Press on your belly to see if organs are larger than usual or tender.