Toxoplasma gondii Antibodies, IgM

The test provides qualitative identification of Toxoplasma gondii IgM antibodies to assist in the presumptive diagnosis of acute or recent toxoplasmosis. Use in conjunction with T. gondii IgG. If IgM is reactive while IgG is nonreactive, repeat both IgG and IgM in approximately two weeks to evaluate seroconversion. In pregnancy, when both IgG and IgM are positive, perform IgG avidity testing to help differentiate recent from remote infection. Toxoplasma gondii Antibodies, IgM (also referred to as Anti-Toxoplasma IgM) is applicable to the evaluation of suspected infection in immunocompromised patients.

Toxoplasma gondii is an obligate intracellular protozoan. Cats serve as the definitive host and shed resilient oocysts that can contaminate soil, food, and water. Humans acquire infection by ingesting oocysts or by consuming tissue cysts present in undercooked meat. In immunocompetent persons, infection is frequently asymptomatic or presents as a mild, self-limited febrile illness. Severe disease is associated with congenital transmission and with immunocompromise, where encephalitis and ocular involvement are common. Following exposure, IgM antibodies generally appear within 1–2 weeks, rise transiently, and then decline over subsequent months. Low-level IgM may persist for extended periods, which can complicate interpretation. Detection of IgM produced by the fetus indicates congenital infection.