Toxoplasma IgG and IgM

Most people have toxoplasmosis without symptoms and do not know whether they have ever had it. Blood IgG and IgM antibody testing shows whether you have previously had toxoplasmosis and are protected, and helps confirm a suspected recent infection. It is most useful for women planning pregnancy or already pregnant, because usually only a first infection during or just before pregnancy can harm the fetus.

Who the test is for

• women planning pregnancy who want to know whether particular care with diet and hygiene will be needed;
• pregnant women, preferably early in pregnancy, when a gynaecologist wants to establish protection;
• pregnant women with fever, fatigue or enlarged lymph nodes, and when ultrasound shows fetal changes;
• people with enlarged neck lymph nodes, fatigue and mild fever lasting weeks without a clear cause;
• people whose ophthalmologist detects retinal inflammation and suspects toxoplasmosis;
• people with weakened immunity, for example before transplantation or with HIV, because previous infection can reactivate.

What the test reveals

Toxoplasma is a tiny parasite. It is most often acquired through undercooked meat, unwashed fruit and vegetables, or soil or sand contaminated with cat faeces. In healthy people infection usually passes unnoticed or like a mild viral illness; the parasite then remains dormant for life.

The test measures two antibody types:

• IgM appear first, in the first weeks after infection, but persist for months and even more than a year in many people.
• IgG appear somewhat later and remain for life, indicating past infection.

IgG and IgM can also be tested separately, but results are most informative together. Alongside toxoplasma, a gynaecologist often also requests antibodies to rubella and cytomegalovirus.

The procedure and preparation

Blood is taken from a vein, taking only a few minutes. No fasting or special preparation is needed. State whether you are pregnant and your pregnancy week. Bring previous toxoplasma antibody results if available: comparison often clarifies uncertain IgM.

What your result means

• IgG negative, IgM negative: you have not had toxoplasmosis and are unprotected. In pregnancy this means precautions, and a gynaecologist may suggest repeat testing.
• IgG positive, IgM negative: you had the infection previously. If testing was performed before or early in pregnancy, the fetus is generally not at risk.
• IgM positive, with or without IgG: recent infection is possible, but so are persistent IgM from an earlier infection or a false-positive result. A doctor usually requests another sample after two to three weeks and may request IgG avidity, showing whether infection is older than approximately four months.
• Borderline result: testing is usually repeated after two to three weeks.

Positive thresholds depend on method and are printed on the report. Positive IgM alone is not a diagnosis. A doctor, or a gynaecologist during pregnancy, interprets results considering pregnancy duration, symptoms and earlier findings. Confirmed infection during pregnancy means additional tests, fetal monitoring and treatment if needed.

How to arrange testing

You can have blood taken without an appointment or referral at one of our branches across Croatia (listed under Contact). Prices for all tests and panels are available in the price list. To check rubella, cytomegalovirus and herpes simplex alongside toxoplasma, a more cost-effective option is the TORCH test.

Frequently asked questions

Is positive toxoplasma IgG a bad result?

No. Positive IgG with negative IgM means previous toxoplasmosis and protection. Before pregnancy this is good news because a first infection during pregnancy, which can harm the fetus, is generally no longer a threat.

What if I have no toxoplasma antibodies?

Eat only thoroughly cooked meat and do not taste raw meat during preparation. Wash fruit and vegetables, wear gardening gloves and wash hands and equipment well after handling raw meat and soil. A gynaecologist may suggest repeat testing during pregnancy.

Must I get rid of my cat if pregnant?

No. Have someone else change the litter. If doing it yourself, wear gloves and change it daily because faeces become infectious only after one to five days. Feed the cat commercial food rather than raw meat.

Can toxoplasmosis occur twice?

In healthy people, previous infection provides lifelong protection, so repeat illness is very rare. The parasite nevertheless remains dormant and can reactivate with severely weakened immunity, for example with HIV or after transplantation.