The toxoplasma test looks for antibodies in the blood to a parasite called toxoplasmosis . The parasite causes an infection called , which poses a danger to a developing baby if a pregnant women gets it. It is also dangerous in people with AIDS.
Toxoplasma serology; Toxoplasma antibody titer
How the test is performed
A blood sample is needed. For information on how this is done, see: Venipuncture
The sample is sent to a lab, where antibodies to are detected using several tests, including an indirect fluorescent antibody test, ELISA, and the Sabin-Feldman dye test.
How to prepare for the test
There is no special preparation for the test.
How the test will feel
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
The test is done soon after pregnancy to detect toxoplasmosis infection in a newborn baby. It may also be used to screen pregnant women for the antibodies to the parasite.
The presence of antibodies before pregnancy probably protects a developing baby against toxoplasmosis at birth. However, antibodies that develop during pregnancy may mean the mother and baby are infected. This increases the risk of miscarriage or birth defects.
This test may also be done if you have:
- Unexplained lymph node swelling
- An unexplained rise in the blood white cell (lymphocyte) count
- HIV and have symptoms of a brain infection (including headache, seizures, weakness, and speech or vision problems)
- Inflammation of the back part of the eye (chorioretinitis)
A titer (measurement of the concentration in a sample) of less than 1:16 indicates that there has likely never been an infection with .
What abnormal results mean
A titer of 1:16 - 1:256 is a sign that you have probably been infected with the parasite sometime in the past.
A titer of greater than 1:1,024 may be a sign of an active toxoplasmosis infection.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Montoya JG, Boothroyd JC, Kovacs JA. Toxoplasma gondii. In: Mandell GL, Bennett JE, Dolin R, eds. . 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap279.
Montoya JG. Toxoplasmosis. In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 357.