Comparative study of the serologic response of IgA and IgM type in the diagnosis of acute toxoplasmosis

BACKGROUND: IgM serologic response in the diagnosis of acute toxoplasmosis presents interpretation problems. A comparative study with IgA detection of antibodies was performed. METHODS: A parallel serologic study was carried out with IgM and IgA enzymoimmunoassay enhancement techniques in the sera of patients suspected of having toxoplasmosis. RESULTS: Positive results for IgM and/or IgA were presented in 74 sera (47 patients): 86.3% for the former and 58.9% for the latter (p < 0.001). The group of IgA-/IgA+ sera presented a low mean of proportionality index (PI): 1.6 versus the IgM+ sera group in the context of IgG seroconversion with a PI of 3.4 (p < 0.001). Out of the 9 patients with demonstrated IgG, all were IgA+ and seven IgM+. CONCLUSIONS: The present data seem to support greater specificity of the determination of IgA antibodies than that of IgM in the diagnosis of acute toxoplasmosis.