Brucellosis

1 What is Brucellosis?

Brucellosis is an infectious disease that spreads through the air or when humans come in contact with animals infected with Brucella bacteria.

Animals that most commonly get infected include sheep, cattle, goats, pigs and dogs.

Most often, the ingestion of animal products contaminated with the bacteria, especially unpasteurized milk, cheese and other dairy products can cause this bacterial infection.

The symptoms of brucellosis include fever, joint pain and fatigue. The infection can be treated successfully with antibiotics.

The treatment may take several weeks to months and recurrences are common.

While brucellosis rarely manifests in the United States, the disease affects hundreds of thousands of people and animals throughout the world.

Avoiding the use of unpasteurized dairy products and taking certain precautions while working with animals or in a laboratory can help prevent brucellosis.

2 Symptoms

Brucellosis symptoms can appear anytime between a few days to months following the infection.

A wide range of signs and symptoms will occur and some may persist for a prolonged period.

Initial symptoms appear similar to those of the flu and include:

Brucellosis symptoms may sometimes disappear for several weeks or months and then reoccur.

In some cases, brucellosis may become chronic with its symptoms persisting for longer periods of time even after treatment.

Long-term signs and symptoms include chronic fatigue, recurrent fevers, arthritis and spondylitis — an inflammatory arthritis that affects the spine and adjacent joints, neurologic symptoms (in up to 5% of cases), inflammation of the heart (endocarditis), swelling of the liver and/or spleen, swelling of the testicle and scrotum area and depression.

Brucellosis in its early stages may be difficult to differentiate from other conditions that occur with similar symptoms such as the flu.

Seek your doctor's advice if you develop a rapidly rising persistent fever, muscle aches or unusual tiredness and if you have any risk factors for the disease.

3 Causes

Brucellosis is caused by immediate contact with Brucella bacteria, which resides in animals and can also become airborne.

Brucellosis generally affects many wild and domestic animals.

Cattle, goats, sheep, pigs, dogs, camels, wild boar and rein deer are more prone to this infectious disease caused by bacteria.

A form of brucellosis may also affect harbor seals, porpoises and certain whales.

Human beings may get infected with brucellosis through one of the three major routes that include:

  • Consumption of under cooked meat or unpasteurized/raw dairy products: Brucella bacteria present in the milk of infected animals such as cattle and goats can spread to humans through intake of unpasteurized milk, ice cream, butter and cheeses. The bacteria can also be transmitted through ingestion of raw or under cooked meat that is obtained from infected animals.
  • Inhalation: Brucella bacteria can spread easily through the air. Breathing in these bacteria may also lead to infection. The risk of inhalation is generally greater in people working in laboratories, on farms, slaughterhouse workers, and meat-packing employees as they are exposed to these bacteria.
  • Direct contact: Bacteria in the blood, semen or placenta of an infected animal may enter your bloodstream through a cut in the skin or mucus membranes. Domestic animals rarely spread brucellosis as normal contact with animals that involves touching, brushing or playing does not cause infection. Also, immuno-compromised people should avoid handling dogs known to have this disease.

Brucellosis usually does not spread from one person to the other, but in few cases, women may transmit the disease to their infants during labor or through their breast milk.

Rarely, brucellosis may spread through sexual activity or through contaminated blood or bone marrow transfusions.

4 Making a Diagnosis

Doctors usually confirm a diagnosis of brucellosis by testing for the Brucella bacteria through a sample of blood or bone marrow.

If you think that you have signs of brucellosis, you may initially consult your family doctor or a general practitioner. You may also be referred to an infectious disease specialist if needed.

A diagnosis of brucellosis is made by understanding how and when you were exposed to the bacteria that caused the disease.

You can help your doctor by being well prepared for your appointment with as much information as possible.

Prior to your appointment, you may keep ready a list of answers to the following questions:

  • When did you first start experiencing your symptoms?
  • Have you consumed raw (unpasteurized) dairy products, such as goat cheese?
  • Does your job involve direct contact with animals or with animal tissues?
  • Have you traveled outside the United States recently?
  • Do you work in a laboratory that tests infectious organisms?
  • Have you been hunting recently?

During the physical examination, your doctor may:

  • Check for pain and stiffness by asking you to move your joints
  • Check your reflexes and muscle strength
  • Palpate your abdomen to check whether there is any organ enlargement or tenderness

Additionally, a blood test may be done to detect the presence of antibodies against the bacteria.

To help detect complications of brucellosis, you may have additional tests, such as:

  • X-rays: X-ray images reveal changes in your bones and joints.
  • Computerized tomography (CT) scan or magnetic resonance imaging (MRI): These imaging tests help in recognizing inflammation or abscesses in the brain and other tissues.
  • Cerebrospinal fluid culture: This test requires a small sample of the fluid collected from the space surrounding your brain and spinal cord for infections such as meningitis and encephalitis.
  • Echocardiography: This test makes use of sound waves to create images of your heart in order to check for signs of infection or tissue damage to your heart.

5 Treatment

The goals of treating brucellosis include providing symptomatic relief, prevention of a relapse of the disease and avoiding complications.

You will be prescribed antibiotics such as doxycycline and rifampin in combination for at least 6-8 weeks.

Inform your doctor if you are:

  • Pregnant
  • Suffering from decreased immune response (immunosuppressed state)
  • Allergic to medicines such as doxycycline or rifampin

Complete recovery from the disease may need several months.

Sometimes, the disease may reoccur or become chronic

6 Prevention

 Brucellosis infection can be prevented by taking the following precautions:

  • Avoid consumption of unpasteurized dairy foods: In recent years in the United States, few cases of brucellosis have been thought to have occurred due to use of raw dairy products from domestic herds. Still, the best method to prevent brucellosis is to avoid unpasteurized milk, cheese and ice cream, irrespective of their origin. If you're traveling to other countries, avoid all raw dairy foods.
  • Pasteurization is a process in which raw milk is heated to a high temperature for a short period of time. This kills harmful bacteria that make milk unsafe to drink. Do not eat any dairy product if you are unsure whether it is pasteurized or not.
  • Cook meat thoroughly: Cook all meat until it reaches an internal temperature of 145 to 165 F (63° to 74° C). When eating out, order beef and pork at least medium-well. It is unlikely that domestic meat in the United States contains Brucella bacteria, but proper cooking destroys other harmful bacteria such as salmonella and Escherichia coli. When traveling abroad, avoid buying meat from street vendors and order meat that is well-cooked.
  • Wear gloves: People who handle animal tissues such as veterinarians, farmers, hunters or slaughterhouse workers, and animal herdsman should protect themselves by wearing rubber gloves, goggles, gown and aprons while handling sick or dead animals or animal tissue or when assisting an animal giving birth. This prevents the bacteria from getting into eyes or a cut or abrasion on the skin.
  • Take safety precautions in high-risk workplaces: If you work in a laboratory, handle all the specimens under appropriate biosafety conditions. Treat all workers who have been exposed immediately. Slaughterhouses should follow few protective measures, such as isolation of the killing floor from other meat processing areas and use of protective clothing.
  • Vaccinate domestic animals: In the United States, an aggressive vaccination program has almost eliminated brucellosis in livestock herds. As the brucellosis vaccine is live vaccine, it can give rise to disease in people. Anyone who has an accidental needle prick while vaccinating an animal should be treated promptly.

7 Risks and Complications

There are several risks and complications associated with brucellosis.

Brucellosis is rarely encountered in the United States.

Other parts of the world that have much higher rates of brucellosis infection, such as:

  • Around the Mediterranean Sea
  • Eastern Europe
  • Latin America
  • Asia
  • Africa
  • The Caribbean
  • The Middle East

People staying in or traveling to these regions are more likely to consume unpasteurized goat cheese, sometimes called village cheese.

Unpasteurized goat cheese that gets imported from Mexico has been linked to many cases of brucellosis in the United States.

Occupations at higher risk

People who work with animals or come into direct contact with infected blood are at a greater risk of developing brucellosis.

Examples of such occupations include:

  • Veterinarians
  • Dairy farmers
  • Ranchers
  • Slaughterhouse workers
  • Hunters
  • Microbiologists

Brucellosis can affect almost any part of your body, including your reproductive system and major organs such as the liver, heart and central nervous system.

Chronic brucellosis may lead to complications in either one organ or all throughout your body.

Possible complications include:

  • Infection of the heart's inner lining (endocarditis): This is one of the most serious complications of brucellosis. Endocarditis, if it goes untreated can cause damage or destroy the heart valves, and is a common cause of brucellosis-related deaths.
  • Arthritis: Joint infection with symptoms such as pain, stiffness and swelling in your joints, particularly the knees, hips, ankles, wrists, and spine.
  • Spondylitis: Inflammation of the joints between the bones (vertebrae) of your spine or between your spine and pelvic bone. This condition is hard to treat and may cause long-term damage.
  • Inflammation and infection of the testicles (epididymo-orchitis): The Brucella bacteria that causes brucellosis may infect the epididymis, the coiled tube that connects the vas deferens and the testicle. The infection may also spread to the testicle itself, causing severe pain and swelling.
  • Inflammation and infection of the spleen and liver: Brucellosis can also involve the spleen and liver, resulting in enlargement beyond their normal size.
  • Central nervous system infections: These are potentially life-threatening disorders such as meningitis, an inflammation of the membranes covering the brain and spinal cord, and encephalitis, which is an inflammation of the brain itself.
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