What is the significance of a positive IgM and negative IgG in a pregnant patient exposed to toxoplasmosis?

A positive IgM and negative IgG in a pregnant patient exposed to toxoplasmosis is significant because it suggests a recent or acute infection with the Toxoplasma gondii parasite. The presence of IgM antibodies indicates the body’s immediate response to the infection, whereas the absence of IgG antibodies means that the patient has not been previously exposed to the parasite.

Given that diagnosing toxoplasmosis, especially in pregnant patients, can have serious implications for both maternal and fetal health, it is crucial to confirm the diagnosis. This is often done through more specific testing, which may include additional serologic tests or polymerase chain reaction (PCR) testing, particularly since false positives can occur with certain serological tests for Toxoplasma.

Thus, while the positive IgM might indicate an acute infection, the definitive diagnosis typically requires further confirmation from a specialized reference laboratory that can provide more accurate testing and diagnostics for toxoplasmosis.