Diagnosis of Human Toxoplasmosis Using Rapid Chromatographic Immunoassay and Enzyme-Linked Immuno-Sorbent Assay (ELISA) Compared to Polymerase Chain Reaction

Abstract

Background: Toxoplasma gondii is an obligate intracellular protozoan pathogen, There are many different procedures for the laboratory diagnosis of Toxoplasma infection in pregnant women, congenitally-infected fetuses and newborns, they are mainly performed by serological testing, and PCR (for confirmatory purpose), beside many commercial diagnostic tests, which use Toxoplasma lysate antigen. These procedures differ from each other based on cost, time-consumption, and accuracy of the test, which should meet patient’s needs. Aim of study: To compare different tests used for diagnosis of T. gondiiin aborted women. Rapid Chromatographic Immunoassay and Enzyme-Linked Immuno- Sorbent Assay (ELISA) were compared to polymerase chain reaction. Materials and Methods: In this study, blood samples were collected from onehundred pregnant women suspected with toxoplasmosis in Baghdad city-Iraq, and diagnosed by three different procedures for the T. gondii infection, rapid chromatographic (IgM or IgG immunoblot), ELISA(IgM or IgG) test. Molecular diagnoses were performed in peripheral blood by PCR and targeting the Toxoplasma gondii B1 gene. The results were described as frequency and percentage of positivity; also, specificity and sensitivity of immunoblot were assessed according to the result of other tests. Results: According to the result of three testing methods, (83%) samples showed positive for T.gondii using Rapid chromatographic method .While with ELISA test, 28 % samples were IgM positive and 72% samples were IgG positive and by PCR technique 92 % positive . Sensitivity and specificity of immunoblot (IgG, 85% and 86%, respectively) (IgM, 88% and 81%, respectively ). Relatively higher sensitivity and specificity was found in ELISA (IgG, 89 % and 91%, respectively) III and specificity ( IgM, 89% and 90%) respectively. While by PCR technique has shown 100 % sensitivity and 99.8% specificity respectively. Conclusion: This study concluded that ELISA test is more suitable for detection of anti-T. gondii IgG and IgM antibodies in both acute and chronic infection compared to the rapid chromatographic test. However, PCR has the highest sensitivity and specificity.