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Brucella is a bacteria that spreads from animals to humans most commonly through ingesting a contaminated food product or direct contact with an infected animal. Human to human contact is very rare.[1] The incidence of confirmed infection in humans in the US hovers just over 100 cases total.[2] The incidence in other parts of the world is higher.[3]

Characteristics[edit | edit source]

Brucella is:

  • Gram-negative - does not retain a crystal violet stain used in the differentiation process
  • coccobacilli - has a shape intermediate between cocci (spherical bacteria) and bacilli (rod-shaped bacteria)
  • non-spore-forming
  • non-motile
  • aerobic - grows in the presence of oxygen
  • zoonotic - spreads to humans from animals

Classification[edit | edit source]

There are six species of Brucella. Three can cause serious disease in humans: Brucella abortus, Brucella melitensis and Brucella suis. One species, Brucella canis causes mild disease and the other two species have not affected humans.[4]

Brucellosis[edit | edit source]

The disease caused by a brucella infection is called brucellosis. It causes an acute febrile illness associated with rigors, sweats, malaise, anorexia, headache, pain in muscles, joint, and/or back, and fatigue. If untreated, it can potentially cause a debilitating chronic infection in humans with reoccurring fevers, arthritis, swelling of the testicle and scrotum area, swelling of the heart (endocarditis), neurologic symptoms (in up to 5% of all cases), chronic fatigue, depression, swelling of the liver and/or spleen.[3][5]

Risk for exposure[edit | edit source]

The people most at risk for acquiring a Brucella infection are people who[6]:

  • consume undercooked meat or unpasteurized (raw) milk products from an infected animal
  • slaughterhouse workers
  • meat-packing plant employees
  • veterinarians
  • hunters dressing an infected animal
  • laboratory workers who handle the bacteria
  • an infant breastfeeding from an infected mother

Treatment[edit | edit source]

Treatment is a combination of broad spectrum antibiotics.[7]

Lean more[edit | edit source]

See also[edit | edit source]

References[edit | edit source]

  1. "Brucellosis". Centers for Disease Control and Prevention. March 8, 2019. Retrieved May 4, 2019.
  2. "Brucellosis Surveillance | References and Resources | Brucellosis | CDC". Centers for Disease Control and Prevention. October 9, 2018. Retrieved May 4, 2019.
  3. 3.0 3.1 Rubach, M.P.; Halliday, J.E.B.; Cleaveland, S.; Crump, J.A. (2013). "Brucellosis in low-income and middle-income countries". Current Opinion in Infectious Diseases. 26 (5): 404–412.
  4. Alton GG, Forsyth JRL. Brucella. In: Baron S, editor. Medical Microbiology. 4th edition. Galveston (TX): University of Texas Medical Branch at Galveston; 1996. Chapter 28. Available from:
  5. "Signs and Symptoms | Brucellosis | CDC". Centers for Disease Control and Prevention. October 9, 2018. Retrieved May 4, 2019.
  6. "Transmission | Brucellosis | CDC". Centers for Disease Control and Prevention. March 11, 2019. Retrieved May 4, 2019.
  7. Michael J. Corbel. (1997). Brucellosis: an Overview. Emerging Infectious Diseases. Vol. 3, No. 2, pp 213-221. DOI: 10.3201/eid0302.970219