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Serology for Brucellosis

What Is Serology for Brucellosis?

Serology is the science dealing with blood serum and especially its immunological reactions and properties. Blood sent for serology means the serum will be tested for antibodies, antigens, and other immune system properties.

Antibodies are proteins made by the immune system. They help to destroy the following that can invade your body:

  • bacteria
  • viruses
  • parasites
  • fungi

If antigens get into the body, they can cause a number of illnesses and diseases. One of these is brucellosis.

Antibodies are structured to target specific antigens. This is why serology not only helps determine whether a person has a current infection but also what type of agent is responsible. The serologic test for brucellosis is often simply known as the Brucella antibody test.

If antibodies for Brucella bacteria are found in your blood, you may have had brucellosis or you may currently have it.

Symptoms of Brucellosis

Brucellosis can be either acute (short-term) or chronic (long-term) infectious disease. The symptoms include:

  • muscle pain
  • joint pain
  • chills
  • profuse sweating
  • fever
  • fatigue
  • weakness
  • back pain
  • swollen glands

Causes of Brucellosis

A class of bacteria called Brucella cause brucellosis. There are several strains of these bacteria that can lead to problems in humans. These are:

  • Brucella melitensis
  • Brucella abortus
  • Brucella suis
  • Brucella canis

The bacteria tend to be passed from animals to humans. Animals that can carry and transmit the Brucella bacteria include:

  • goats
  • sheep
  • cattle
  • camels
  • pigs
  • dogs (rarely)

Brucella is not transmitted to humans through casual contact such as touching. There’s an extremely low risk of getting brucellosis from eating the meat of an infected animal if it’s fully cooked.

Most cases of brucellosis are due to direct contact with the bodily fluids of infected animals. These include urine and blood. It can also be passed on by direct contact with the tissues, placentas, and aborted fetuses of infected animals.

Eating unpasteurized dairy products made from the milk of infected animals can also put you at risk.

Purpose of a Serologic Test for Brucellosis

The bacteria that cause brucellosis are not passed easily from animals to humans. Also, many people don’t come into contact with animals that normally carry Brucella. As a result, testing will likely be ordered if you have the symptoms and you were in a situation where infection could have occurred.

People at higher risk than the general population include farm workers and veterinarians. Slaughterhouse workers and meat inspectors also have a higher-than-average risk.

Procedure for a Serologic Test for Brucellosis

ICON: Process

If your doctor suspects you have brucellosis, you’ll need to provide a blood sample to be analyzed.

This isn’t a complicated procedure, and shouldn’t cause any severe pain or discomfort. Your doctor will insert a needle into a vein and collect a small amount of blood in a vial. It will then be analyzed in the lab. The test usually used to analyze your blood is called a Brucella agglutination test.

Understanding the Results of Serology for Brucellosis

Antibodies are produced in response to the Brucella infection. A person who wasn’t exposed to Brucella shouldn’t have any antibodies for the bacteria in their blood.

An absence of Brucella antibodies is considered a normal result. If you do have these antibodies, it means you are or were likely infected with the bacteria.

False Positives and Other Concerns About Reliability

There are a few reasons why diagnosing an active Brucella infection can be challenging.

  • Some other types of bacteria can cause a false positive, which means testing positive for the presence of Brucella when it’s not present.
  • Some immunizations can cause a test to be positive when there’s no infection.
  • A positive test doesn’t always mean you have a current infection. It could mean you were exposed to Brucella at some point in the past. It might also mean you have an immunity against this type of bacteria.
  • If you were recently exposed to the Brucella antigen, there may be too few antibodies to be detected by the test.

More tests or follow-up testing may be needed to confirm or rule out brucellosis.

How Is Brucellosis Treated?

As with the vast majority of bacterial infections, brucellosis is treated with antibiotics. The duration of the treatment will depend on factors such as whether there are any complications. It’s possible for people who have been treated to relapse. The symptoms can also persist for a long time, sometimes even years.

It’s important to keep in mind that brucellosis is very rare. In fact, there are only 100 to 200 cases of it per year in the United States. If your doctor does suspect you have brucellosis, following up with testing and treatment is vital to increase your chances of a full recovery.

Content licensed from:

Written by: Krista O'Connell
Medically reviewed on: Jan 04, 2016: Mark LaFlamme, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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