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Brucellosis is a bacterial infection caused by a group of bacteria that can affect both humans and animals. In majority of the cases, this disease spreads from infected animals to human beings or through inhalation of contaminated air. Intake of contaminated milk or raw meat can allow this bacteria to enter your body and cause infection. Mild to moderate forms of brucellosis resemble flu symptoms, but a severe form can present with multiple complications that involve your heart and joints. Brucellosis can be treated with the use of antibiotics. 


The causative bacteria of this infection belong to the genus Brucella. These bacteria can infect both animals and humans. Animals that can get infected by this bacteria include sheep, goats, cattle, pigs, wild dogs, deer, camels, and some other species. Humans contract the disease from infected animals in three ways. The most common way of spreading is by eating raw or undercooked meat and drinking unpasteurized milk. Intake of products made from unpasteurized milk, such as cheese, butter, etc., is equally dangerous. This bacteria can also transfer if you come in contact with the blood, urine, semen, or birth products of an infected animal.


Another mode of transmission is through inhalation. Brucella bacteria are scattered around in the air around infected animals. People who work closely with these animals can contract this infection through the inhalation of bacteria. This infection does not spread from human to human, but rare cases of vertical transmission, i.e., mother to child during birth or breastfeeding, have been reported. 

Risk Factors And Epidemiology

Brucellosis is more prevalent among people who work with domestic animals or live close to farms. Farmers, in particular, are at high risk because their occupation makes them exposed to the pathogen at all times. Veterinary doctors, livestock farmers, hunters, ranchers, slaughterhouse workers, and animal researchers are also at high risk. If you live close to a farm or travel through an area with active cases of infection, you can be at risk because the air may contain Brucella bacteria.


Brucellosis is rare in the United States. According to the Centers for Disease Control and Prevention (CDC), around 140 cases of brucellosis are reported each year in the US. Brucellosis is more prevalent in other regions, including Southern Europe, Eastern Europe, Asia, Africa, The Caribbean, and the Middle East. Men are more commonly affected than women. 

Signs And Symptoms

The signs and symptoms of brucellosis may take a few weeks or a few months to develop because the bacteria has a long incubation period. Once the bacteria become active, you may develop flu-like symptoms, including fever, headache, chills, tiredness, loss of appetite, weakness, back pain, and joint pain. These symptoms may disappear and recur after some time. Chronic brucellosis can persist for years, even after getting appropriate treatment. It can lead to further complications, including fever, endocarditis, arthritis, sacroiliitis, and spondylitis


History and brief physical examination is made to look for the symptoms of brucellosis. History of traveling or living close to animals can give an indication. It is difficult to base the diagnosis on symptoms alone because they may be absent in some cases. The conformational diagnosis of brucellosis can be made by testing for the bacteria in blood, urine, or bone marrow. If any complications of brucellosis are suspected, your doctor may require additional tests, including cerebrospinal fluid culture, joint x-rays, CT scan, MRI, and echocardiography. 

Differential Diagnosis

Signs and symptoms of brucellosis can be confused with other diseases, which include typhoid fever, Q-fever, malaria, leptospirosis, dengue fever, tuberculosis, toxoplasmosis, cytomegalovirus disease, rheumatic disease, and HIV. Differentiation should be done on the basis of history and diagnostic tests. 


The mainstay of treatment for brucellosis is the use of antibiotics. A combination of doxycycline and streptomycin is used to treat this condition. Antibiotics are taken for 2 to 3 weeks to reduce the risk of recurrence. In case of pregnant females, rifampicin is the drug of choice. Antibiotics may be different for children depending on their age and the severity of their condition. Rest is recommended along with treatment. Strenuous work or heavy physical activity should be avoided because it can cause more weakness and increase the risk of joint pain. In some cases of chronic brucellosis, the infection may return after treatment. Contact your doctor in such a case to look for further treatment options. 


Majority of the cases of brucellosis are treated completely by using antibiotics. It is important to take antibiotics for the prescribed period, or else a recurrent infection can occur. Risk of complications such as arthritis or endocarditis in those cases where brucellosis persists for a long period of time. The mortality rate due to this infection is less than 1%. 


Brucellosis can be prevented by avoiding its modes of transmission from animals to humans. Avoid eating raw, undercooked meat and unpasteurized dairy products. If you are not sure whether the milk or milk products are pasteurized or not, ask your provider until it is confirmed. People who work with animals should take special precautions to prevent this infection. Wear eye protection and gloves before handling discharge materials or birth products of animals. Wash your hands thoroughly after handling animals. Pet animals do not contract brucellosis in most cases, but if you have a weak immune system, care should be taken around them as well. Animal researchers or laboratory workers should also follow all the recommended safety guidelines to avoid the risk of infection and its spread.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 13, 2023.



Brucellosis (who.int) - https://www.who.int/news-room/fact-sheets/detail/brucellosis#:~:text=sheep%20and%20dogs-,Brucellosis%20is%20a%20bacterial%20disease%20caused%20by%20various%20Brucella%20species,or%20by%20inhaling%20airborne%20agents.

CDC - Home - Brucellosis - https://www.cdc.gov/brucellosis/index.html