A Comparative Study of the Sensitivity and Specificity of IgM and IgG Assay Techniques in the Diagnosis of Toxoplasmosis

Toxoplasmosis is a common disease between human and animal with an extensive distribution. It is caused by the parasitical protozoan Toxoplasma gondii. Most clinical laboratories have problems with the diagnosis of toxoplasmosis. The aim of this study is the comparison of sensitivity and specificity of conventional and unconventional methods in the diagnosis of Toxoplasmosis based on the measurement of IgM and IgG and introduction of the best method. Patients and In this comparative analytical study, from 100 people that physicians suspected of having the Toxoplasmosis symptoms and had been introduced to two laboratories in Tehran and Karaj for toxoplasmosis testing. Serum specimens were prepared and tested with Enzyme-linked immunoadsorbent assay(ELISA), Indirect fluorescent assay(IFA), Chemiluminescence(CLIA) and Enzyme linked fluorescent assay(ELFA). Data was analyzed via Chi-Square. In comparison with the IgG ELFA method, the IgG CLIA has the most sensitivity, specificity, positive and negative predictive values(100%). In comparision with IgM ELFA, IgM CLIA and IgM ELISA had the same sensitivity(92%), but IgM ELISA had more specificity(100%) than IgM CLIA(97.3%). In IgM ELISA positive and negative predictive values were 100% and 97.4% respectively and in IgM CLIA they were 96% and 98% respectively. Although results of the comparative methods are near to each other, the automatic methods(CLIA, ELFA) are preferred because of a high reproducibility, reduced personnel expenses, time saving, etc. Therefore we suggest using these methods for diagnosing Toxoplasmosis. Also it is suggrsted that for measuring IgM, the mentioned methods are the most suitable of diagnostic methods.