The Toxoplasma IgG Avidity test helps determine whether a Toxoplasma gondii infection is recent (acute) or past (chronic) by measuring the strength (avidity) of IgG antibodies against the parasite.
✅ Low avidity → Recent infection (within the last 3–5 months)
✅ High avidity → Past infection (longer than 4–5 months ago)
✅ Assess Recent Infection in Pregnancy – Determines if the infection occurred before or during pregnancy (important for congenital toxoplasmosis risk).
✅ Confirm Timing of Infection – In cases where both Toxoplasma IgM and IgG are positive.
✅ Differentiate Active vs. Past Infection – Helps avoid unnecessary treatment.
| Avidity Level | Interpretation | Infection Timing |
|---|---|---|
| Low Avidity (<30%) | Suggests recent or active infection | Within 3–5 months |
| Borderline (30–40%) | Unclear; retesting may be needed | Possible recent infection |
| High Avidity (>40%) | Suggests past infection | More than 4–5 months ago |
📌 A high avidity result excludes recent infection, even if IgM is positive.
📌 A low avidity result suggests recent infection but must be confirmed with other tests.
📌 Toxoplasma PCR (Blood/Amniotic Fluid) – Confirms active infection, especially in pregnancy.
📌 Ultrasound/Fetal MRI – Checks for congenital toxoplasmosis effects in pregnant women.
📌 Repeat IgG & IgM Tests – Helps track antibody changes over time.
✔ Toxoplasma IgG Avidity helps distinguish recent vs. past infection, especially in pregnancy.
✔ A high avidity result rules out a recent infection, avoiding unnecessary treatment.
✔ A low avidity result suggests a recent infection but must be confirmed with additional tests.