A toxoplasmosis test is a blood test that determines if you have serum antibodies to the Toxoplasma gondii parasite. It’s also called a toxoplasma test.
Your body only makes the antibodies after the T. gondii parasite infects you. The number and type of antibodies you have indicates whether your infection was recent or it 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. The condition is often asymptomatic. However, if a pregnant person contracts the infection, it may pass to their fetus.
Eating raw or undercooked meat from an infected animal puts you at risk of a T. gondii infection. You may also contract the infection after handling an infected cat or its feces, which can happen when cleaning a litter box.
After you contract the infection, you’ll have the T. gondii antibodies as long as you live. This generally means that you can’t have the infection again.
Your doctor may wish to conduct a toxoplasmosis test under the following circumstances:
- You’re pregnant, and they want to know whether you have T. gondii antibodies.
- You’re pregnant, and they want to determine whether your unborn baby has toxoplasmosis.
A T. gondii infection can cause brain damage and blindness in a developing baby. Your doctor can test a sample of amniotic fluid, which is the fluid that surrounds your baby in the womb, to see if they have the infection.
Your doctor may also want to test you if you have a weakened immune system due to an illness such as HIV. A weakened immune system puts you at a greater risk of contracting toxoplasmosis and other infections.
No specific preparation is necessary for the test.
However, you should let your doctor know if you’ve 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 take a blood thinner.
To test an adult or a child for T. gondii, a healthcare professional will take a sample of blood from their arm. Giving a blood sample involves the following steps:
- First, the healthcare professional will clean the site with a swab of rubbing alcohol.
- They’ll then insert the needle into a vein and attach a tube to fill with blood.
- After drawing enough blood, they’ll remove the needle and cover the site with a gauze pad.
Testing your baby
If you’re pregnant and you currently have a toxoplasmosis infection, there’s a chance that your baby will contract the infection, so your doctor will need to perform further tests.
According to a 2014 study, if toxoplasmosis is left untreated, the chances of your baby contracting it are around:
- 25 percent in the first trimester
- 54 percent in the second trimester
- 65 percent in the third trimester
Your doctor can perform an amniocentesis after the first 15 weeks of pregnancy.
They’ll use a very fine needle to remove a small amount of fluid from the amniotic sac, which is the sac that surrounds your baby. A laboratory will then test the fluid for signs of toxoplasmosis.
As with any blood test, there’s a minimal risk of minor bruising at the needle site.
In rare cases, the vein may swell or become inflamed after a blood draw. This condition is known as phlebitis. Applying a warm compress to the swollen area several times per day can help treat phlebitis.
Ongoing bleeding could be a problem if you have a bleeding disorder or if you’re taking a medication that thins your blood, such as:
- warfarin (Coumadin, Jantoven)
- ibuprofen (Advil, Motrin)
- naproxen (Aleve, Naprosyn)
- other anti-inflammatory drugs
Risks associated with amniocentesis
Amniocentesis carries a slight risk of miscarriage. The test can sometimes also cause:
- abdominal cramping
- irritation at the site of the injection
- fluid leakage at the site of the needle insertion
Your antibody levels can be measured in international units per milliliter (IU/mL).
Reference ranges will vary by lab and will depend on which assay, or investigative procedure, was used.
For example, for the Quest Diagnostics test, a result greater than 8.79 IU/mL is considered positive for toxoplasmosis. A result between 7.2 and 8.79 IU/mL is considered equivocal, and a result less than 7.2 IU/mL is considered negative.
For the Mayo Clinic Laboratories test, a result greater than or equal to 12 IU/mL is considered positive. A result between 10 and 11 IU/mL is considered equivocal, and a result less than or equal to 9 IU/mL is considered negative.
Test results will usually be ready within 3 days.
According to regulations from the
Did you know?
Toxoplasmosis antibodies form within 2 weeks after an infection. They’ll reach their highest levels 1 or 2 months after infection.
If you have acute toxoplasmosis, your doctor may recommend one of the following treatments:
Pyrimethamine (Daraprim) is a malaria treatment that’s also commonly used for toxoplasmosis.
Sulfadiazine is an antibiotic used in combination with pyrimethamine to treat toxoplasmosis.
Treatments for pregnant people and babies
If you have a toxoplasmosis infection but your baby doesn’t, your doctor can prescribe the antibiotic spiramycin.
This drug has approval in Europe to be used for toxoplasmosis, but the United States still considers it experimental. Use of this drug will decrease your baby’s chances of getting a toxoplasmosis infection, but it won’t interfere with normal growth and development.
Your doctor may prescribe pyrimethamine and sulfadiazine if your baby has an infection, but only if the situation is extreme. This is because both of these drugs can have harmful side effects for you and your unborn baby.
The bottom line
Treatment may reduce the severity of the disease, but it can’t reverse the damage that’s already been done.