What is brucellosis?
Brucellosis is a bacterial disease that is classified as zoonotic, meaning it is most often a disease of animals that is occasionally transmitted to humans. There are three major types of Brucella bacteria that affect humans: Brucella suis (found in goats). B. abortus (cattle) and B. melitensis (sheep). Humans may become infected with this disease through contact with infected animals or animal products. Other names for brucellosis include:
- Mediterranean fever
- Rock fever (or Gibraltar fever)
- Bang’s disease
- Malta fever (or Maltese fever)
- Undulant fever
- Cyprus fever
How common is brucellosis?
Brucellosis is found all over the globe. However, those places with poor public health and poor domestic animal health programs are at a higher risk. For example, Africa, Asia, and Eastern Europe are more at risk for brucellosis. In the United States, brucellosis is rare in cattle (who are vaccinated) but can be found in buffalo and elk populations in the West.
How do you become infected with brucellosis?
You can become infected with brucellosis by:
- Consuming undercooked meat
- Consuming raw dairy items
- Inhaling bacteria which cause brucellosis
- Touching infected animals
These are mostly animals that we associate with farming, such as sheep, cows, goats, and pigs. However, dogs can also be carriers, as can wild animals such as elk.
While brucellosis is unlikely to spread person-to-person, there is a chance it could be spread through breast milk, blood transfusions, or tissue transplants. However, this is not routine.
Symptoms and Causes
What causes brucellosis?
Bacterial infections cause brucellosis. It is an infectious disease which animals can transmit to people through close contact. These animals include cows, sheep, goats, pigs, and dogs. The bacteria can also be contained in animal products, such as dairy. Thus, people become infected by consuming these products.
What are the symptoms of brucellosis?
The following are the first signs of brucellosis:
- Muscle, joint, back discomfort
- Weakness, ill-feeling
- Loss of appetite
The following are symptoms that may come back, last for a long while, or not go away:
- Fevers that come and go
- Inflammation of joints
- Inflammation of testicles or scrotum
- Inflammation of the heart
- Inflammation of liver, spleen
- Emotional changes
- Issues with the nervous system (up to 5% of patients)
Diagnosis and Tests
How is brucellosis diagnosed?
Brucellosis is diagnosed through a sample of blood or bone marrow which is sent for bacterial culture, serology (antibodies to the bacteria) or molecular testing (polymerase chain reaction or PCR).
Management and Treatment
How is brucellosis treated?
The treatment for brucellosis is antibiotics. This treatment can last 6 to 8 weeks, or even longer. Two or more antibiotics are typically used. This helps lower the risk of drug resistance and reoccurrence of the disease.
Those infected patients who are pregnant, have a limited immune system, or are allergic to the antibiotics will need to speak with a doctor further to discuss options.
What are the complications associated with brucellosis?
Complications associated with brucellosis include chronic infections causing relapsing fevers and occasionally infective endocarditis, bone infection or meningitis.
Can brucellosis be prevented?
Vaccination of cattle with brucellosis vaccine (RB51) works by producing an immune response that increases the animals resistance to the disease. There is no human vaccine.
Brucellosis in humans can be prevented by careful attention to the consumption of cooked meats and dairy goods. Consuming pasteurized milk ensures it will be safe due to the bad bacteria being destroyed through a heating process.
Laboratory workers or hunters should take precautions when handling animals. Wearing rubber gloves, gowns, and goggles will keep infectious bacteria from getting into skin wounds or eyes.
Who is at risk of developing brucellosis?
Those at risk of developing brucellosis include:
- People who consume unpasteurized dairy products
- Laboratory technicians working with the bacteria
- Workers in meat-packing plants
- Workers in slaughterhouses
- Employees working with animals or in close contact with animal excretions
- Hunters with wounds who touch an infected animal, who eat undercooked meat, or who breathe in bacteria while preserving the meat
Commonly hunted animals which may be infected include wild hogs, moose, bison, and elk.
Outlook / Prognosis
What is the outlook for patients who have brucellosis?
People diagnosed with brucellosis recover relatively well and have a positive prognosis, especially if they consult with a doctor during the disease's early stages. The disease is treatable. However, there is a chance of it coming back or not going away at all.
Pregnant women who have become infected with brucellosis need to consult with their doctor immediately. Antibiotics could be prescribed, as well as lab tests. Quick attention to the infection may be able to save the baby from harm.
Other patients may take a small number of weeks to many months to fully recover. After recovery, it is still possible for patients to become sick again. Death from brucellosis is uncommon. Around 2% of patients will succumb to the disease. Persons diagnosed with brucellosis who also have a heart condition due to an inflammation of the heart have a more severe prognosis, with around 85% succumbing to the disease.
What resources are available to learn more about brucellosis?
To learn more about brucellosis, contact the Centers for Disease Control and Prevention (cdc.gov).
Other useful resources for more information include:
- The National Organization for Rare Disorders (rarediseases.org)
- The United States Department of Agriculture (usda.gov)
- Orphanet portal for rare diseases (orpha.net)
- The Monarch Initiative database (monarchinitiave.org)
- Learn about clinical trials for brucellosis at ClinicalTrials.gov.