Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at March 9, 2016

Brucellosis is a contagious bacterial infection that spreads from animals to humans. Contact with infected animals as well as consuming unpasteurized dairy or ingesting infected meat can cause this disease. Brucellosis is also known as Malta fever, Mediterranean fever, or undulant fever.


Definition & Facts

Brucellosis rarely occurs in the United States with 100-200 cases being reported a year. Brucella bacteria may infect pigs, goats, cattle, camels and dogs. Those who work in jobs where they come into contact with animals or meat, such as farmers, veterinarians or butchers are at a higher risk for contracting the disease.

Symptoms & Complaints

Brucellosis produces several flu-like symptoms which can make it hard to diagnose. Common symptoms include:

Brucellosis takes the name "undulant fever" from the spiking of fever, which usually occurs in the afternoons. Signs and symptoms may begin a few days after initial infection to a few months. Brucellosis can become chronic and symptoms may last for years even with treatment. Long-term symptoms include arthritis, fevers, fatigue, and spondylitis - a kind of inflammatory arthritis that affects the spine and any adjacent joints.

Since brucellosis can be mistaken for flu during its early stages, it can be difficult to determine when to see a physician. If a person is at risk for exposure to Brucella bacteria and develops muscle aches, a rapidly rising or persistent fever, or unexplained weakness, he or she should see a doctor to determine if he or she has been infected or not.

There are several complications that may arise as a result of brucellosis including sores or lesions, arthritis complications, meningitis, encephalitis, or endocarditis.


Brucellosis is usually transmitted to humans from domestic or wild animals. Goats, cattle, dogs, pigs, sheep, camels, reindeer and wild boar are susceptible to the disease. Brucella bacteria are transmitted from animals to humans in a number of ways including:

  • Unpasteurized dairy products­­- Consumption of raw or unpasteurized milk, ice cream, cheese and butter can spread brucellosis. This is the most common way brucellosis is spread.
  • Raw or undercooked meat of infected animals.
  • Direct contact with blood, semen or placenta of infected animals. Brucella bacteria can enter into the human bloodstream through a cut or open wound.
  • Inhalation. Brucellosis can spread easily through air so veterinarians, slaughterhouse workers, lab technicians or other occupations that handle at-risk animals can contract it through inhalation.

Person-to-person spreading of brucellosis is rare but it can happen. Mothers who may be infected with the disease may pass it onto their children during birth or through breast milk. Spreading of brucellosis through sexual activity or contaminated blood is also rare.

Diagnosis & Tests

The most common test for brucellosis is a blood test to detect antibodies to the Brucella bacteria. Bone marrow is also tested in the same manner. In addition a physician may order some of the following tests to detect any other complications of brucellosis:

A comprehensive patient history will also be taken. If brucellosis is suspected the following questions may help lead doctors to a correct diagnosis:

  • Does the patient work in an environment where they may come in contact with Brucella bacteria, such as a slaughterhouse, meat packing facility, farm, veterinary hospital or laboratory?
  • Has the patent recently traveled overseas?
  • If so, is it possible they consumed undercooked meat or unpasteurized dairy products?
  • Does the patient hunt? (Moose, elk, wild hogs and caribou can carry brucellosis.)
  • Has the patient assisted animals with giving birth?

Treatment & Therapy

Treatment for brucellosis focuses on relieving symptoms, since symptoms can last for several months. Brucellosis can also return and become chronic making management of symptoms the best relief. Once a doctor has made a diagnosis of brucellosis a course of antibiotics will be prescribed.

Tetracycline, ciprofloxacin, rifampin, sulfamethoxazole/trimethoprim and doxycycline are oral medications that may be prescribed for up to six weeks. Gentamicin and streptomycin may also be prescribed as injections. Because of the risk for developing complications, continued physician's care ensures that a more serious condition does not result and continues to treat the symptoms. 

Prevention and Prophylaxis

Brucellosis can be prevented through education and taking precautions against infection by avoiding the causes.

  • Avoid unpasteurized dairy. One of the best ways to protect against brucellosis is to avoid consuming raw dairy. No matter where they originated from abstaining from eating unpasteurized ice cream, milk or cheese is one of the best ways to prevent brucellosis infection. If traveling to other countries it is advised to avoid consuming all raw dairy at all.
  • Cook meat completely. Meat should be cooked until it reaches an internal temperature of 145 degrees Fahrenheit (63 degrees Celsius) between 165 degrees Fahrenheit (74 degrees Celsius) in order to ensure harmful bacteria has been destroyed. This is also good advice to protect against E. Coli bacteria or salmonella. When ordering beef or pork ask for meat to be cooked to at least medium-well. Do not buy meat from street vendors.
  • Wear personal protective equipment if working in an environment where contact with infected animals may be likely. Veterinarians, farmers, slaughterhouse workers and hunters should take appropriate precautions when handling sick or dead animals and when assisting animals in giving birth.
  • Controlling brucellosis in animals is the best way to prevent it from transmitting to humans. There is a vaccination available for cattle which has helped with the control of brucellosis in the United States. However there is no such vaccination that exists for humans.