Comparison of the Toxogen® rapid test with ELISA immunoenzymatic technique for toxoplasmosis serology in pregnant women

Abstract

The aim of this study was to compare the technical performance of the Toxogen® rapid test against the ELISA technique for serological screening and/or serological monitoring of toxoplasmosis in pregnant women. Methods and material: A prospective, descriptive and analytical study was conducted over a period of 7 months from January to July 2018. One hundred and eighty-two toxoplasmosis serologies were carried out on 144 pregnant women followed in two hospitals in Mahajanga and in a private laboratory in Antananarivo. Two serologies were performed for each case, the first by the rapid test Toxogen®, a latex agglutination test, and the second by the IgG-ELISA and IgM-ELISA technique. Results: The Toxogen® rapid test had a sensitivity of 62.5%, a specificity of 97.1%, a Positive Predictive Value of 94.3%, a Negative Predictive Value of 76.7% compared to the IgG-ELISA technique. The correlation between the dilution titer by the Toxogen® rapid test and the optical density (OD) of anti-toxoplasmics IgG by the ELISA technique was very low (r² = 0.17, p <0.001). The crude prevalence of toxoplasmosis was 30,6% (n=44) by the Toxogen® rapid test and 46.5% (n=67) by the IgG-ELISA technique, the difference was significant (p <0.001). We had 2 cases (0.01%) positives by the IgM-ELISA which were not detected by the Toxogen® rapid test. Conclusion: The Toxogen® rapid test cannot substitute the ELISA technique for the serological screening and/or serological monitoring of toxoplasmosis in pregnant women.