Novel IgM-based lateral flow assay for diagnosis of congenital Chagas disease

BackgroundThe diagnosis of congenital Chagas disease in newborns relies on the microhematocrit method which exhibits reduced sensitivity during the early stages of infection and quantitative PCR for Trypanosoma cruzi, which is applied only in specialised centre due to its technical complexity. Consequently, the majority of congenital transmission cases are confirmed after an extended period of serological monitoring, resulting in delayed treatments and reduced cure rates. The need for new, accurate tests for the timely diagnosis of the disease in newborns is evident.ObjectivesWe developed a lateral flow assay based on IgM detection (IgM-LFA) using the novel chimeric antigen CP4, which have demonstrated high performance in IgM-ELISA, as previously reported by our group.MethodsThe accuracy of IgM-LFA was evaluated comparatively with IgM-ELISA using 28 serum samples from infants up to three months old, congenitally infected (n = 11) or non-infected (n = 17) with T. cruzi. Additionally, it was assessed for its agreement with microhematocrit and quantitative PCR, through estimating the Cohen's Kappa coefficient (k).ResultsThe IgM-LFA showed 100% specificity and 81.82% sensitivity and IgM-ELISA gave 100% specificity and sensitivity when evaluated against the standard algorithm diagnosis for congenital Chagas disease. Notably, the IgM-LFA identified two additional cases in relation to microhematocrit and showed a correlation of k = 0.84 with quantitative PCR, corresponding to almost perfect agreement with this molecular test.ConclusionThese results suggest that IgM-LFA has the potential to facilitate decentralised detection of congenital Chagas disease, contributing to the early and enhance detection of infected newborns.