Finding the right tests…
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Finding the right tests…
ELISA
Most people who catch Toxoplasma gondii, a parasite spread through undercooked meat, unwashed produce, or contact with cat faeces or contaminated soil, never notice any symptoms - and this blood test is how a past infection like that gets confirmed years later. A positive IgG result means you were infected at some point, and for most people this now means lasting protection rather than an ongoing problem. In pregnancy specifically, checking for this existing immunity before conception tells a doctor whether the mother is already protected, since it's a first-time infection during pregnancy - not old immunity - that actually puts the baby at risk.
The result is reported as a positive or negative IgG antibody status, sometimes with a titre showing how strong the antibody response is. A positive result before pregnancy is generally reassuring, since it means the infection already happened and typically protects a developing baby from a first-time infection later. If IgG is positive at the same time as IgM, the timing becomes less clear, and an additional test called IgG avidity is used to help work out whether the infection is old or genuinely recent.
Unlike many infections, past exposure to Toxoplasma gondii is generally reassuring rather than concerning, because the immunity it leaves behind protects a future pregnancy from a first-time infection - the situation that actually carries risk for the baby. A positive IgG result taken before or early in pregnancy confirms that protection is already in place.
- Undercooked or cured meat, including pork, lamb, and venison - Unwashed fruit and vegetables, or contaminated water - Soil contact during gardening, or contact with cat faeces, usually through litter box cleaning - Rarely, an organ transplant or blood transfusion from an infected donor
Cats can shed the parasite in their faeces for a short window after their own first infection, which is why litter box hygiene gets specific mention in prevention advice - daily cleaning and wearing gloves reduce the risk considerably. Owning a cat does not by itself make infection likely for most people with normal hygiene habits.
If your IgG is positive but timing matters - most importantly during pregnancy - your doctor adds an IgM test and sometimes an IgG avidity test, which measures how tightly your antibodies bind the parasite and strengthens the longer ago an infection happened.
Before pregnancy, it's generally reassuring, since it usually means lasting immunity that protects a future pregnancy from a first-time infection. Your doctor only becomes concerned if IgM is also positive, which can suggest a more recent infection.
Not necessarily - most guidance recommends practical precautions like daily litter box cleaning and using gloves, rather than avoiding cats altogether. Ask someone else to handle litter box duty if possible, and wash your hands well afterward.
It measures how tightly your antibodies bind the parasite, which increases the longer ago an infection happened. It's used when IgG and IgM are both positive and your doctor needs to work out whether the infection is old or recent, especially during pregnancy.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
Yes, undercooked or cured meat, including pork, lamb, and venison, is one of the more common ways people are infected. Cooking meat to a safe internal temperature reduces this risk substantially.
There's no fasting requirement for this test. Ask your doctor or the centre when you book, particularly if it's part of a wider antenatal panel.
No, most people with a positive IgG result and no IgM or symptoms need no treatment at all, since it simply reflects past exposure. Treatment is reserved for active infection, pregnancy with a new infection, or people with weakened immune systems.