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Medical Author:

Steven Doerr, MD

Steven Doerr, MD

Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

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Medical Editor:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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In this Article

• What is brucellosis?
• What is the history of brucellosis?
• What causes brucellosis?
• How is brucellosis transmitted?
• What are the symptoms and signs of brucellosis?
• How is brucellosis diagnosed?
• What is the treatment for brucellosis?
• What are the complications of brucellosis?
• How can brucellosis be prevented?
• Brucellosis At A Glance
• Brucellosis Index

Brucellosis is a systemic infectious disease transmitted from certain animals to humans (zoonotic disease). Brucellosis in humans is predominantly caused by four different species of Brucella bacteria: Brucella melitensis (goats, sheep, camels), Brucella suis (pigs), Brucella abortus (cows, buffalo, elk, camels, yaks), and Brucella canis (dogs). Though all of these species can cause human brucellosis, Brucella melitensis is the most prevalent worldwide, and it is felt to cause the most severe cases of brucellosis.

Brucellosis is transmitted from animals to humans in several ways. The most common route of transmission occurs when humans consume raw milk or cheese from infected sheep and goats. Infected animals shed the organism into their milk, and if humans eat or drink unpasteurized dairy products from these affected animals, they can develop brucellosis.

Brucellosis can also be transmitted to humans via inhalation of the organism or by direct contact with infected animal secretions. The bacteria can gain entry into the body through the inhalation of aerosolized secretions, through breaks in the skin, or through exposure of the mucous membranes/conjunctiva from the splashing of infected secretions. With these routes of entry, brucellosis is an occupational disease that can affect veterinarians, slaughterhouse workers, butchers, hunters, laboratory personnel, and those individuals who work closely with livestock (for example, farmers and shepherds).

Finally, an accidental injection with the livestock vaccine used against Brucella abortus can also lead to brucellosis in humans. Human-to-human transmission is very rare (via sexual contact and breastfeeding).