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Brucellosis

Last updated: January 28, 2021

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Brucellosis is a zoonotic infection caused by different species of Brucella, a genus of gram-negative bacteria. The most common vectors of the disease are cattle, sheep, goats, and pigs. Transmission occurs through the ingestion of contaminated animal products, contact with infected animals, or inhalation of bacteria. Although brucellosis is a major public health concern in many countries, it has become rare in the United States as a result of animal health policies. Brucellosis manifests with flu‑like symptoms. However, hepatomegaly, splenomegaly, lymphadenopathy, and focal organ infection (e.g., osteomyelitis, endocarditis, spondylitis) may also occur. Recommended treatment is a combined regimen of doxycycline and rifampin.

  • Pathogen: Brucella spp. are facultative intracellular, gram-negative, aerobic, coccobacilli. [1]
    • Brucella melitensis: mainly affects sheep, goats, and camels → Malta fever
    • Brucella abortus: mainly affects cattle, but also bison, deer, and elk → Bang disease
    • Rare causes of disease in humans
      • Brucella suis: mainly affects (feral and domestic) pigs and reindeer, but also cattle and bison
      • Brucella canis: affects dogs
  • Transmission: zoonotic [2]
    • Contaminated food, esp. raw meat, unpasteurized dairy products
    • Contact with infected animals
  • Risk factors: occupational or recreational exposure to infected animals and animal products (e.g., farmers, veterinarians, hunters, slaughterhouse workers, laboratory personnel)
  • Pathophysiology: Brucella spp. survive and replicate within macrophages of the reticuloendothelial system → formation of noncaseating granulomas

Brucellosis manifests as UNdulant fever and the causative pathogen is transmitted by UNpasteurized dairy products.

References: [3]

References: [3]

  1. Humans and Brucella Species. https://www.cdc.gov/brucellosis/clinicians/brucella-species.html. Updated: November 12, 2012. Accessed: October 31, 2020.
  2. Brucellosis: Transmission. https://www.cdc.gov/brucellosis/transmission/index.html. Updated: November 12, 2012. Accessed: April 10, 2017.
  3. Brucellosis. https://rarediseases.org/rare-diseases/brucellosis/. . Accessed: October 31, 2020.
  4. CDC - Brucellosis treatment. https://www.cdc.gov/brucellosis/treatment/index.html#:~:text=Generally%2C%20the%20antibiotics%20doxycycline%20and,allergic%20to%20doxycycline%20or%20rifampin. . Accessed: October 9, 2020.
  5. Herold G. Internal Medicine. Herold G ; 2014