UCSF

Confirmed diagnosis of chronic Chagas disease (CD) requires positive results by two different IgG serology tests. Variable sensitivity has been reported among tests and in different geographic regions. Inadequate specificity presents a particular challenge in low-prevalence settings such as the United States. This study provides a direct comparison of the latest-generation IgG serology assays with four previously assessed FDA-cleared tests. Seven hundred ten blood donor plasma specimens were evaluated by Wiener Lisado and Wiener v.4.0 enzyme-linked immunosorbent assays (ELISAs) and Abbott PRISM Chagas chemiluminescent assay (ChLIA). Sensitivity and specificity were assessed relative to infection status as determined by the original blood donation testing algorithm. All three latest-generation assays demonstrated 100% specificity (95% confidence interval [CI], 98.6 to 100.0). Wiener Lisado, Wiener v.4.0, and Abbott PRISM had sensitivities of 97.1% (95% CI, 95.1 to 98.4), 98.9% (95% CI, 97.4 to 99.6), and 95.5% (95% CI, 93.2 to 97.3), respectively. As with previously evaluated FDA-cleared tests, all three assays had the highest reactivity and sensitivity in samples from donors born in South America and lowest reactivity and sensitivity in specimens from those born in Mexico, with intermediate results in specimens from Central American donors. Wiener v.4.0 had the highest diagnostic sensitivity in all comparisons. Our findings suggest that the latest-generation CD serology tests could improve diagnostic sensitivity without affecting specificity.