Brucellosis (Brucella Bacteria Infection)

What is brucellosis?

Brucellosis (Bang’s disease, Malta fever, Undulant fever, Mediterranean fever) is a highly infective zoonotic disease (disease that spreads from animals to humans) that is usually transmitted through the ingestion of unpasteurized milk, meat of infected animals and contact with body secretion of the animals. Even transmission from human-to-human and mother-to-child is possible although rare. Fever, sweating, body ache, muscle pain are the most common presenting features of brucellosis. Antibiotic therapy (tetracycline, rifampicin, streptomycin) is the mainstay of treatment. Pasteurization of milk and milk products (cheese) and proper handling of animals can prevent brucella infection.

Brucellosis Symptoms

Brucellosis may present acutely or become a chronic illness lasting for years.

Acute Brucellosis

Acute brucellosis presents with the following symptoms :

  • Mild flu-like syndrome.
  • Fever: the disease is also called the “ undulant fever” as there is a high spike in temperature every afternoon associated with swollen glands.
  • Lethargy.
  • Abdominal pain.
  • Back pain.
  • Chill.
  • Profuse sweating (with characteristic smell described as that of “wet hay”).
  • Headaches.
  • Loss of appetite.
  • Moving (migratory) muscle and joint pain, body ache (malaise).
  • Loss of weight.

Chronic Brucellosis

Brucella can persist in the cells leading to symptoms of chronic illness :

  • Damage to the heart (endocarditis): common cause for brucella-related deaths.
  • Arthritis (joint damage of knee, hip, ankle) and spondylitis (vertebral column) may cause disability if not treated.
  • Damage of testes, prostate or the  kidneys.
  • Meningitis (damage of meninges that covers the brain and spinal cord) and encephalitis (damage of brain).

Causes of Brucellosis

Brucellosis is a zoonotic disease that usually spreads from infected animals to humans. There are several different species of Brucella bacteria that infect specific animals and can be transmitted to humans.

Picture of Brucella species of bacteria from the CDC Public Health Image Library

Animals that carry brucellosis

Both domestic and wild animals can carry the disease. Cattles, goat, sheep, dogs, camels and reindeers are usually known to carry the disease. Wild bears are another common carrier of the Brucella bacteria but humans rarely come in close contact with these animals. Even harbor seals and whales may be affected by a particular form of brucellosis.

Transmission of brucellosis

  • Consumption of raw (unpasteurized) milk, milk products (cheese, ice-creams) and meat of the infected animals can lead to the disease.
  • Inhalation: Brucella spp resists drying and can therefore easily survive in the environment and spreads by this route especially among dairy farmers, slaughter house workers and microbiologists
  • Contact with body fluids (blood, semen) and placenta of infected animals may spread the disease. Although normal contact (touching, brushing) with animals do not spread the disease people with immune deficiency should avoid contact with animals having Brucella infection.
  • Rarely sexual contact with an infected person, between infected mother and child, transfusion of infected blood or bone marrow transplantation can cause brucellosis.

Who is at risk of brucellosis?

Brucellosis is rare in the United States and European countries (Malta and the UK) are currently free from brucellosis. People who are at risk are those who :

  • Consume unpasteurized milk or milk product (cheese) including organic varieties sourced from infected animals.
  • Animal handling (veterinarians, laboratory workers, dairy farmers, rancher, slaughter house workers, hunters) from the body fluids and tissues.

Although principally brucellosis spreads from animals to human, it can spread via human to human contact. Therefore sexual contact with an infected person can be a risk factor.

Brucellosis Treatment

The focus should lie on the prevention of brucellosis. This can be achieved through pasteurization of milk and proper handling of infected animals. However, the infection can be effectively treated with antibiotics since it is a bacterial infection.There are only specific antibiotics that are effective in eradicating the Brucella bacteria.


Tetracycline, rifampicin and aminoglycosides (streptomycin, gentamicin) are effective against brucellosis. Usually a combination of these antibiotics are used for as long for six weeks to prevent relapse of the infection.

References :

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