Brucellosis is an infectious disease caused by bacteria. People can get the disease when they are in contact with infected animals or animal products contaminated with the bacteria. Animals that are most commonly infected include sheep, cattle, goats, pigs, and dogs, among others.
Transmission
Humans are generally infected with brucellosis in one of three ways:
Eating undercooked meat or consuming unpasteurized/raw dairy products
The most common way to be infected is by eating or drinking unpasteurized/raw dairy products. When sheep, goats, cows, or camels are infected, their milk becomes contaminated with the bacteria.
If the milk from infected animals is not pasteurized, the infection will be transmitted to people who consume the milk and/or cheese products.
Breathing in the bacteria that cause brucellosis (inhalation)
Breathing in the bacteria that causes brucellosis may also lead to infection. This risk is generally greater for people in laboratories that work with the bacteria. In addition, slaughterhouse and meat-packing employees have also been known to be exposed to the bacteria and ultimately become infected.
Bacteria entering the body through skin wounds or mucous membranes
Bacteria can also enter wounds in the skin/mucous membranes through contact with infected animals.
This poses a problem for workers who have close contact with animals or animal excretions (newborn animals, fetuses, and excretions that may result from birth). Such workers may include:
- slaughterhouse workers
- meat-packing plant employees
- veterinarians
People who hunt animals may also be at risk. When they are in contact with infected animals, exposure to the bacteria may occur through:
- skin wounds
- accidentally ingesting undercooked meat
- inhaling the bacteria while dressing their game. Commonly infected animals include: bison, elk, caribou, moose and wild hogs (feral swine).
Person-to-person spread of brucellosis is extremely rare. Infected mothers who are breast-feeding may transmit the infection to their infants. Sexual transmission has been rarely reported. While uncommon, transmission may also occur via tissue transplantation or blood transfusions.
Signs and Symptoms
Brucellosis can cause of range of signs and symptoms, some of which may present for prolonged periods of time.
Initial symptoms can include:
- fever
- sweats
- malaise
- anorexia
- headache
- pain in muscles, joint, and/or back
- fatigue
Some signs and symptoms may persist for longer periods of time. Others may never go away or reoccur.
These can include:
- recurrent fevers
- arthritis
- swelling of the testicle and scrotum area
- swelling of the heart (endocarditis)
- neurologic symptoms (in up to 5% of all cases)
- chronic fatigue
- depression
- swelling of the liver and/or spleen
Risk of Exposure
Areas at Risk
Although brucellosis can be found worldwide, it is more common in countries that do not have 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)
- Mexico, South and Central America
- Eastern Europe
- Asia
- Africa
- The Caribbean
- The Middle East
Risks from Unpasteurized Dairy Products
Unpasteurized cheeses (sometimes called "village cheeses") from areas at increased risk for brucellosis may represent a particular risk for tourists.
Developing countries often do not have safeguards that can help prevent or monitor possible outbreaks, such as pasteurization laws, animal control/slaughter regulations, and brucellosis surveillance programs.
When traveling in these areas, some people may unknowingly consume unpasteurized dairy products. People from the U.S. who travel to these areas should:
- recognize that milk and dairy products may not be pasteurized and could be unsafe to consume.
- only consume meat products which are thoroughly cooked, since many countries cannot ensure brucellosis-free meat products.
Occupational Risks
People in certain occupations or settings may face increased exposure to the bacteria that cause brucellosis. These can include:
- slaughterhouse workers
- meat-packing employees
- veterinarians
- laboratory workers
Hunters may also face increased risk of exposure. Some game animals that can transmit brucellosis include:
- wild hogs (feral swine)
- elk
- bison
- caribou
- moose
Risks for Expecting Mothers
- Women who are pregnant and have been exposed to brucellosis should consult with their obstetricians/healthcare provider for evaluation. Laboratory tests and a short course of antibiotics also known as post-exposure prophylaxis (PEP) may be recommended.
- Prompt diagnosis and treatment of brucellosis during pregnancy can be lifesaving for the fetus.
- While rare, human-to-human transmission from lactating mothers to their breastfed infants has been reported.
- If you have been diagnosed with brucellosis, please consult with your obstetrician/healthcare provider for healthy nursing options.
Treatment
Generally, the antibiotics doxycycline and rifampin are recommended in combination for a minimum of 6-8 weeks. Let your doctor know if you are:
- pregnant
- allergic to doxycycline or rifampin
- suffer from a reduced or absent immune response (immunosuppressed)
Before treatment begins, a diagnosis of brucellosis infection must be made by a doctor.
Tests will be performed to look for bacteria in samples of blood, bone marrow, or other body fluids. In addition, a blood test can be performed to detect antibodies against the bacteria.
Once a diagnosis is made, a doctor can prescribe antibiotics.
Depending on the timing of treatment and severity of illness, recovery may take a few weeks to several months. Death from brucellosis is rare, occurring in no more than 2% of all cases.
Prevention
The best way to prevent brucellosis infection is to be sure you do not consume:
- undercooked meat
- unpasteurized dairy products, including:
Pasteurization is when raw milk is heated to a high temperature for a short period of time. This heating process destroys harmful bacteria that may make the milk unsafe to consume.
If you are not sure that the dairy product is pasteurized, do not eat it.
People who handle animal tissues (such as hunters and animal herdsman) should protect themselves by using:
This will help ensure that bacteria from potentially infected animals do not get into eyes or inside a cut or abrasion on the skin.
