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toxoplasmosis test is a blood test that checks for
antibodies to the Toxoplasma gondiiparasite. Your body's natural defense system (immune system) will make these antibodies only if you
have been infected by this tiny parasite. The amount and type of antibodies you
have shows whether your infection is recent or occurred in the past. More than
one blood test may be done over several weeks.
For most people,
toxoplasmosis is not dangerous and goes away on its own. But if a pregnant
woman becomes infected and passes it on to her growing baby (fetus), it can cause blindness and brain damage in the
You can become infected by eating food such as undercooked
or raw meat from an infected animal or by handling an infected cat or its stool
(feces). After you have been infected, you will have antibodies to
Toxoplasma gondii for the rest of your life, so you
cannot be infected again.
To see if your growing baby is
infected, the test can be done on a sample of the fluid that is around your
baby (amniotic fluid) taken during
A toxoplasmosis test is done to check if
Tell your doctor if you are pregnant and
have contact with a cat or clean a cat's litter box. Before your blood is
drawn, let your doctor know if you have bleeding or clotting problems, or if
you take blood-thinning medicine.
You do not need to do anything
else before you have this test.
The health professional taking a sample
of your blood will:
The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
There is very little chance of problems from
having blood drawn from a vein. You may get a small bruise at the site. You can
lower your chance of bruising by keeping pressure on the site for several
In rare cases, the vein may become swollen after the
blood sample is taken. This problem is called phlebitis. You can use a warm
compress several times a day to treat this.
Ongoing bleeding can be a problem for people with bleeding
disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can
make bleeding more likely. If you have bleeding or clotting problems, or if you
take blood-thinning medicine, tell the doctor before your blood is
toxoplasmosis test is a blood test that checks for antibodies to the Toxoplasma gondii parasite. The results of the test are usually given in
titers. A titer is a measure of how much the blood sample can be diluted with a
saltwater solution (saline) before the antibodies can no longer be found. Test
results are usually ready in 1 to 3 days.
A titer of 1 to 8 (1:8)
means that antibodies can be found when 1 part of the blood sample is diluted
by up to 8 parts of a saltwater solution (saline). A larger second number means
there are more antibodies in the blood. So a titer of 1 to 128 means there are
more toxoplasmosis antibodies in the blood than a titer of 1 to 32.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range that your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
IgM in babies:
IgM in adults:
Less than 1:64
Less than 1:1024
Toxoplasmosis antibodies usually form within 2 weeks after
being infected. The titer is the highest 1 to 2 months after infection.
Other infections can cause a
false-positive result in a newborn.
antibodies, such as
rheumatoid factor or antinuclear antibodies, may also
cause a false-positive result.
To learn more about toxoplasmosis
infection in pregnancy, see the topic
Toxoplasmosis During Pregnancy.
Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.
Current as of:
June 4, 2014
Sarah Marshall, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology
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