Evaluation of the Abbott ARCHITECT Toxo IgM assay

Chemiluminescent microparticle immunoassay-based detection and prevalence of Toxoplasma gondii infection in childbearing women (Iran)

Toxoplasmosis is a common zoonotic disease, which is of particular importance in women before and during pregnancy. In this study, the chemiluminescent microparticle immunoassay was used to detect Toxoplasma gondii and the seroepidemiology of Toxoplasma gondii was investigated among childbearing women in Qom, Iran. In this study, 202 blood samples were collected from childbearing women for evaluation of toxoplasmosis. Serum samples were isolated to determine anti-Toxoplasma IgM and IgG antibodies. Based on findings, the total prevalence of anti-Toxoplasma antibodies was 134 (66.3%) [95% CI 59.6-72.5]. In addition, 133 (65.8%) [95% CI 59.1-72.1], 19 (9.4%) [95% CI 6.1-14.2] and 18 (8.9%) [95% CI 5.7-13.6] samples were IgG-positive, IgM-positive and positive for both antibodies, respectively. The highest infection rate was reported over the age of 35 years, and positive lgM antibodies were detected in women below 29 years. T. gondii infection showed a significant correlation with age, pregnancy, contact with cats, exposure to soil, and consumption of raw food (P < 0.05). The serological tests revealed that nearly 33.7% [95% CI 27.5-40.4] of women at childbearing age (49.1% [95% CI 36.4-61.9] of pregnant women versus 27.9% [95% CI 21.3-35.6] of non-pregnant women) had no anti-Toxoplasma antibodies. Therefore, this population is more prone to acute infections with Toxoplasma.

Performance of Zika Assays in the Context of Toxoplasma gondii, Parvovirus B19, Rubella Virus, and Cytomegalovirus (TORCH) Diagnostic Assays

Infections during pregnancy that may cause congenital abnormalities have been recognized for decades, but their diagnosis is challenging. This was again illustrated with the emergence of Zika virus (ZIKV), highlighting the inherent difficulties in estimating the extent of pre- and postnatal ZIKV complications because of the difficulties in establishing definitive diagnoses. We reviewed the epidemiology, infection kinetics, and diagnostic methods used for Toxoplasma gondii, parvovirus B19, rubella virus, and cytomegalovirus (TORCH) infections and compared the results with current knowledge of ZIKV diagnostic assays to provide a basis for the inclusion of ZIKV in the TORCH complex evaluations. Similarities between TORCH pathogens and ZIKV support inclusion of ZIKV as an emerging TORCH infection. Our review evaluates the diagnostic performance of various TORCH diagnostic assays for maternal screening, fetal screening, and neonatal screening. We show that the sensitivity, specificity, and positive and negative predictive value of TORCH complex pathogens are widely variable, stressing the importance of confirmatory testing and the need for novel techniques for earlier and accurate diagnosis of maternal and congenital infections. In this context it is also important to acknowledge different needs and access to care for different geographic and resource settings.

Evaluation of the LDBIO point of care test for the combined detection of toxoplasmic IgG and IgM

The toxoplasma ICT IgG-IgM rapid diagnostic test for the simultaneous detection of specific toxoplasmic immunoglobulin (Ig) G and IgM was compared with the Architect fully automated chemiluminescence test. Four hundred sera were included, among which 248 scored negative in Architect. The cassettes were easily read with the naked eye. Diagnostic sensitivity and specificity were 97% and 96%, respectively. The test scored 8 false-positive IgG and yielded negative results in 3 sera displaying unspecific IgM in Architect. The LDBIO appears to be a reliable first line test, although the false-positive results for IgG deserve further investigation. Such an easily performed test could be used advantageously for screening for toxoplasmosis in pregnant women.

Help in the Choice of Automated or Semiautomated Immunoassays for Serological Diagnosis of Toxoplasmosis: Evaluation of Nine Immunoassays by the French National Reference Center for Toxoplasmosis

Toxoplasmosis, a benign infection, is asymptomatic or paucisymptomatic in over 80% of cases, except in immunocompetent patients suffering from ocular toxoplasmosis or in immunocompromised patients with opportunistic or congenital toxoplasmosis. Diagnosis is based mainly on serology testing. Thus, we compared the performance of the nine most commonly used commercial automated or semiautomated immunoassays for IgG and IgM Toxoplasma gondii antibody detection, that is, the Advia Centaur, Architect, AxSYM, Elecsys, Enzygnost, Liaison, Platelia, VIDAS, and VIDIA assays. The assays were conducted on four panels of serum samples derived during routine testing from patients with an interfering disease and who exhibited a low IgG antibody level in one of two clinical settings, namely, acute or chronic toxoplasmosis. As a result, IgG sensitivities ranged from 97.1% to 100%, and IgG specificities ranged from 99.5% to 100%. For IgG quantification, strong differences in IgG titers (expressed in IU/ml) were noted depending on the assay used. IgM sensitivities ranged from 65% to 97.9%, and IgM specificities ranged from 92.6% to 100%. For defining the best serological strategies to be implemented, it appears crucial to compare the diagnostic performance of the different tests with respect to their specificity and sensitivity in detecting the presence of IgG and IgM antibodies.

Performance characteristics of current-generation Immulite 2000 TORCH Assays

The performances of seven Immulite 2000 (Siemens Healthcare Diagnostics) TORCH (Toxoplasma gondii, other microorganisms, rubella virus, cytomegalovirus, and herpes simplex virus) assays were evaluated in comparison with the performances of the ETI-MAX 3000 (DiaSorin) TORCH assays. The two systems demonstrated good agreement, and given their sensitivity, specificity, and positive predictive value, they can be used with confidence for TORCH prenatal screening.

Evaluation of the Roche Elecsys Toxo IgG and IgM electrochemiluminescence immunoassay for the detection of gestational Toxoplasma infection

Unidentified gestational infection with Toxoplasma gondii may lead to fetal infection with severe complications later in childhood. Because diagnosis of maternal infection solely depends on serology, routine tests with high sensitivity and specificity are required. In this study, the new Roche Elecsys Toxo IgG and IgM immunoassay was compared with Sabin-Feldman dye test and immunosorbent agglutination assay-IgM as reference test. Serum samples were analyzed from 927 pregnant women, including 100 negative, 706 chronic, and 121 acute infections. The combination of both Elecsys IgG and IgM assays demonstrated high sensitivity and specificity of 97.1% and 100.0%, respectively, and a positive and negative predictive value of 100.0% and 81.3%, respectively. The Elecsys assay is a useful tool as a first-line screening method to detect gestational infections. However, if gestational infection is assumed, confirmatory testing by a reference laboratory might be necessary to discriminate between pre- and postconceptional infection to start antiparasitic treatment to avoid mother-to-fetus transmission and severe sequelae.