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What is brucellosis?

Brucellosis is an infectious disease caused by the bacteria of the genus Brucella.  These bacteria are primarily passed among animals, and they cause disease in many different vertebrates primarily sheep, goats, cattle, deer, elk, pigs, and dogs.  The disease causing organisms that infect humans are B.abortus (cattle), B.melitensis (goat and sheep), B. suis (pigs) and rarely B.canis (dogs).  Brucellosis is not very common in the United States, where 100 to 200 cases occur each year, but can be very common in countries that do not have good standardized and effective public health and domestic animal health programs.  Areas currently listed as high risk are the Mediterranean Basin (Portugal, Spain, Southern France, Italy, Greece, Turkey, North Africa), South and Central America, Eastern Europe, Asia, Africa, the Caribbean, and the Middle East. Unpasteurized cheeses, sometimes called "village cheeses," from these areas may represent a particular risk for tourists.


Can brucellosis be spread from person to person?

Direct person-to-person spread of brucellosis is extremely rare. Mothers who are breast-feeding may transmit the infection to their infants. Sexual transmission has also been reported. For both sexual and breast-feeding transmission, if the infant or person at risk is treated for brucellosis, their risk of becoming infected will probably be eliminated within 3 days. Although uncommon, transmission may also occur via contaminated tissue transplantation.

What are the symptoms of brucellosis?

Brucellosis is a systemic bacterial disease with acute or insidious onset, characterized by continued, intermittent or irregular fever of variable duration with headache, weakness, profuse sweating, chills, arthralgia, depression, weight loss and generalized aching.  Localized infections of organs, including the liver and spleen, and arthritic complications and genitourinary infections can also occur.  The disease may last for several days, months or occasionally a year or more if not adequately treated.

How is brucellosis transmitted to humans, and who is likely to become infected?
Humans are generally infected in one of three ways: eating or drinking something that is contaminated with Brucella, breathing in the organism (inhalation), or having the bacteria enter the body through skin wounds. The most common way to be infected is by eating or drinking contaminated milk products. When sheep, goats, cows, or camels are infected, their milk is contaminated with the bacteria. If the milk is not pasteurized, these bacteria can be transmitted to persons who drink the milk or eat cheeses made from it. Inhalation of Brucella organisms is not a common route of infection, but it can be a significant hazard for people in certain occupations, such as those working in laboratories where the organism is cultured. Inhalation is often responsible for a significant percentage of cases in abattoir employees. Contamination of skin wounds may be a problem for persons working in slaughterhouses or meat packing plants or for veterinarians. Hunters may be infected through skin wounds or by accidentally ingesting the bacteria after cleaning deer, elk, moose, or wild pigs that they have killed.

How is brucellosis diagnosed?

Brucellosis is diagnosed in a laboratory by finding Brucella organisms in samples of blood or bone marrow. Also, blood tests can be done to detect antibodies against the bacteria. If this method is used, two blood samples should be collected 2 weeks apart.

Is there a treatment for brucellosis?

Yes, but treatment can be difficult. Doctors can prescribe effective antibiotics. Depending on the timing of treatment and severity of illness, recovery may take a few weeks to several months. Mortality is low (<2%), and is usually associated with endocarditis.

Is there a way to prevent infection?
Yes. Do not consume unpasteurized milk, cheese, or ice cream while traveling. If you are not sure that the dairy product is pasteurized, don't eat it. Hunters and animal herdsman should use rubber gloves when handling viscera of animals. There is no vaccine available for humans.

My dog has been diagnosed with brucellosis. Am I at risk?

B. canis is the species of Brucella species that can infect dogs. This species has occasionally been transmitted to humans, but the vast majority of dog infections do not result in human illness. Although veterinarians exposed to blood of infected animals are at risk, pet owners are not considered to be at risk for infection. This is partly because it is unlikely that they will come in contact with blood, semen, or placenta of the dog. The bacteria may be cleared from the animal within a few days of treatment; however re-infection is common and some animal body fluids may be infectious for weeks. Immunocompromised persons (cancer patients, HIV-infected individuals, or transplantation patients) should not handle dogs known to be infected with B. canis.


See Also...
  CDC's Web Site
Brucellosis Information

Contact Information:

Division of Epidemiology

275 East Main Street
Frankfort, KY 40621

(502) 564-3418 or
(502) 564-3261


Last Updated 10/31/2006