CLSI document M36-A—Clinical Use and Interpretation of Serologic Tests for Toxoplasma gondii; Approved Guideline is intended to aid laboratorians and physicians in determining the status of patients potentially infected with Toxoplasma gondii. Because Toxoplasma organisms are rarely detected in humans infected with the parasites, immunodiagnostic methods are used to indicate the presence of the infection by detecting Toxoplasma-specific antibodies or parasite material in body fluids. Clinical toxoplasmosis can be categorized into four groups: 1) acquired in the immunocompetent patient; 2) acquired or reactivated in the immunodeficient patient; 3) ocular; and 4) congenital. Methods of diagnosis and their interpretations differ for each clinical category. This guideline summarizes the current methods of choice to diagnose toxoplasmosis and discusses the challenges associated with serologic testing for Toxoplasma.

This guideline provides the user with information about the biology of Toxoplasma gondii; the methods available for use in the laboratory diagnosis of human toxoplasmosis; the techniques that should be performed for specific clinical situations; the interpretation of the laboratory results; and the problems inherent in these methods.