The presence of both IgM and IgG antibody in toxoplasmosis infections suggests that the infection

• A. Is Chronic.
• B. Occurred More Recently Than 18 Months Ago.
• C. Has Resolved Itself.
• D. Occurred More Than 2 Years Ago.

Answer: (B)

Having both IgM and IgG indicates a recent infection. IgM is produced early in the immune response and tends to wane after months, while IgG appears soon and remains long-term. When both are present in toxoplasmosis, it means the body has recently mounted an immune response, placing the infection within a relatively recent time frame, typically within the past year or so and certainly not long after 18 months. If the infection had occurred well over a year ago, IgM would usually be absent or very low, and you’d expect to see IgG alone. For more precise timing, clinicians may use IgG avidity testing, where low avidity supports a recent infection and high avidity suggests an older one.