Toxoplasma Test

Written by Corinna Underwood | Published on July 25, 2012
Medically Reviewed by Brenda B. Spriggs, MD, MPH, FACP

Overview

A toxoplasma or toxoplasmosis test is a blood test that is used to determine if you have the antibodies to protect your body from the Toxoplasma gondii parasite in your body. Your body only makes these antibodies once you have been infected by this parasite. The number and type of antibodies you have reveal whether your infection was recent or occurred some time ago. Your doctor may conduct more than one blood test over a period of several weeks.

For most adults, toxoplasmosis is harmless and goes away without the need for treatment. If a pregnant woman becomes infected, however, the infection may pass to the fetus and could cause brain damage and blindness in the growing child. To see if your baby has become infected, your doctor can test a sample of the amniotic fluid (the fluid that surrounds your baby in the womb).

You are at risk of infection by Toxoplasma gondii when you eat raw or undercooked meat from an animal that was infected. You may also catch it by handling an infected cat or its feces. Once you are infected, you will have the Toxoplasma gondii antibodies as long as you live. This means that you cannot be infected again.

Who Requires a Toxoplasma Test?

Your doctor may wish to conduct a toxoplasmosis test if you have any of the following conditions:

  • if you are pregnant and you have Toxoplasma gondii antibodies
  • if your baby has toxoplasmosis
  • if you have a weakened immune system as a result of an illness such as HIV, which means you are at a greater risk of contracting toxoplasmosis

Where and How Is the Test Administered?

Getting Tested

In order to test an adult or child for Toxoplasma gondii, the doctor will need to take a sample of blood from the patient’s arm. First, the site will be cleaned with a swab of rubbing alcohol. The needle will then be inserted into a vein and a tube will be attached to fill with blood. When enough blood has been drawn, the needle is removed and the site is covered with a gauze pad.

According to regulations laid out by the Centers for Disease Control and Prevention, the blood sample must then be analyzed by a laboratory specializing in the diagnosis of toxoplasmosis.

Testing Your Baby

If you are pregnant and currently have a toxoplasmosis infection, there is a 30 to 40 percent chance that your baby will become infected, so your doctor will need to perform further tests.

Amniocentesis

This procedure can be performed safely after the first 15 weeks of pregnancy. Your doctor will use a very fine needle to remove a small amount of fluid from the sac that surrounds your baby (the amniotic sac). The fluid will then be tested in the laboratory for signs of toxoplasmosis.

Ultrasound

Although ultrasound cannot diagnose toxoplasmosis, it can show signs that your baby might be infected, such as fluid buildup on the brain.

Understanding the Results

Your results will usually be ready within three days.

The results are measured in titers. A titer is the amount of salt water needed to dilute the blood until no more antibodies can be detected. Toxoplasmosis antibodies form within two weeks after infection. The titer will reach the highest level one or two months after infection.

If a titer of 1:16 to 1:256 is found, this means you were probably infected in the past. If a titer of 1:1,024 or greater is found, this is probably a sign of an active infection.

What Are the Risks of the Test?

As with any blood test, there are minimal risks of experiencing minor bruising at the needle site. In rare cases, the vein may become swollen or inflamed after blood is drawn. This condition, known as phlebitis, can be treated by applying a warm compress to the swollen area several times each day. Ongoing bleeding could be a problem if you suffer from a bleeding disorder or you are taking blood-thinning medication such as warfarin (Coumadin), aspirin, or other anti-inflammatory drugs like ibuprofen (Advil) or naproxen (Alleve).

Amniocentesis does carry a slight risk of miscarriage. The test can sometimes also cause minor side effects such as abdominal cramping, irritation, or leaking fluid where the needle was inserted.

Preparation for the Toxoplasma Test

No preparation is needed for the test. You should let your doctor know if you have been in contact with a cat or if you clean a litter box. You should also tell your doctor if you have problems with clotting or bleeding or if you are taking blood-thinning medication.

What to Expect After the Test

If you are healthy, you probably won’t need any treatment for toxoplasmosis. But if you are suffering from acute toxoplasmosis, your doctor may prescribe one of the following medications:

Pyrimethamine (Daraprim)

This is a treatment for malaria that is often used for the treatment of toxoplasmosis. Your doctor may ask you to take additional folic acid, because pyrimethamine can cause folic acid deficiency. It can also lower vitamin B12 levels.

Sulfadiazine

This is an antibiotic used in combination with pyrimethamine (Daramine) to treat toxoplasmosis.

Treating Pregnant Women and Babies

If you are infected with toxoplasmosis but your baby is not infected, your doctor will prescribe could prescribe the antibiotic spiramycin. This drug is approved for use in this condition in Europe but is still considered experimental in the U.S. .Use of this drug will decrease your baby’s chances of becoming infected and is will not interfere with normal growth and development.

If your baby is infected, your doctor may prescribe pyrimethamine and sulfadiazine, but only if the situation is extreme, as both of these drugs can have harmful side effects for you and your unborn child. Though treatment may reduce the severity of the disease, it cannot reverse the damage that has already been done.

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