A toxoplasma test is a blood test that determines if you have serum antibodies to the Toxoplasma gondii parasite. It’s also called a toxoplasmosis test. Your body only makes these antibodies after you’ve been infected by this parasite. The number and type of antibodies you have indicate 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. This can 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, which is the fluid that surrounds your baby in the womb.
You’re at risk of infection by T. gondii when you eat raw or undercooked meat from an infected animal. You may also catch it by handling an infected cat or its feces, which can happen when cleaning their litter box. After you become infected, you’ll have the T. gondii antibodies as long as you live. This generally means that you can’t be infected again.
Your doctor may wish to conduct a toxoplasmosis test to determine if:
- you’re pregnant and have T. gondii antibodies
- your baby has toxoplasmosis
Your doctor may also want to test you if you have a weakened immune system due to an illness that puts you at a greater risk of contracting toxoplasmosis, such as HIV.
No specific preparation is necessary 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 take a blood thinner.
To test an adult or child for T. gondii, a healthcare provider will take a sample of blood from your arm. Giving a blood sample involves the following steps:
- First, a healthcare provider 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.
According to regulations by the Centers for Disease Control and Prevention (CDC), a laboratory specializing in the diagnosis of toxoplasmosis must analyze the blood sample.
Testing Your Baby
If you’re pregnant and currently have a toxoplasmosis infection, there’s a 30 percent chance that your baby will become infected, so your doctor will need to perform further tests.
Your doctor can perform an amniocentesis after the first 15 weeks of pregnancy. Your doctor will 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.
Although an ultrasound can’t diagnose toxoplasmosis, it can show signs that your baby might have an infection, such as fluid buildup on the brain.
Risks Associated with a Blood Test
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. Applying a warm compress to the swollen area several times per day can treat this condition, which is known as phlebitis.
Ongoing bleeding could be a problem if you have a bleeding disorder or if you’re taking a blood thinner such as:
- warfarin (Coumadin)
- ibuprofen (Advil)
- naproxen (Alleve)
- other anti-inflammatory drugs
Risks Associated with Amniocentesis
Amniocentesis carries a slight risk of miscarriage. The test can sometimes also cause abdominal cramping, irritation, or fluid leakage at the site of the needle insertion.
Your results will usually be ready within three days.
The units used when measuring the results are known as 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 an infection. The titer will reach the highest level one or two months after infection.
If the lab analysis finds a titer of 1:16 to 1:256, this means you probably have had a toxoplasmosis infection in the past. A titer of 1:1,024 or greater is probably a sign of an active infection.
If you have acute toxoplasmosis, your doctor may advise one of the following treatments:
Pyrimethamine (Daraprim) is a treatment for malaria that’s also a common treatment for toxoplasmosis. Your doctor may ask you to take additional folic acid because pyrimethamine can cause folic acid deficiency. It can also lower your vitamin B-12 levels.
This is an antibiotic used in combination with pyrimethamine (Daraprim) to treat toxoplasmosis.
Treating Pregnant Women and Babies
If you have a toxoplasmosis infection but your baby doesn’t, your doctor can prescribe the antibiotic spiramycin. This drug has approval to be used for this condition in Europe, 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 because both of these drugs can have harmful side effects for you and your unborn child. Treatment may reduce the severity of the disease, but it can’t reverse the damage that has already been done.