Evaluation and validation of a PrintrLab-based LAMP assay to identify Trypanosoma cruzi in newborns in Bolivia: a proof-of-concept study

• Published in: The Lancet. Microbe 2024-09, Vol.5 (9), p.100887, Article 100887
• Main Authors: Rojas Panozo, Lizeth, Rivera Nina, Silvia, Wehrendt, Diana P, Casellas, Aina, Pinto, Lilian, Mendez, Susana, Kuo, Chi-Wei, Lozano, Daniel F, Ortiz, Lourdes, Pinazo, Maria-Jesus, Picado, Albert, Sanz, Sergi, Abril, Marcelo, Gascon, Joaquim, Wong, Season, Schijman, Alejandro G, Torrico, Faustino, Alonso-Padilla, Julio
• Format: Article
• Language: English
• ISSN: 2666-5247; 2666-5247
• DOI: 10.1016/S2666-5247(24)00110-1

Vertical transmission of Trypanosoma cruzi represents approximately 20% of new Chagas disease cases. Early detection and treatment for women of childbearing age and newborns is a public health priority, but the lack of a simple and reliable diagnostic test remains a major barrier. We aimed to evaluate the performance of a point-of-care loop-mediated isothermal amplification (LAMP) assay for the detection of T cruzi. In this proof-of-concept study, we coupled a low-cost 3D printer repurposed for sample preparation and amplification (PrintrLab) to the Eiken T cruzi-LAMP prototype to detect vertically transmitted T cruzi, which we compared with standardised PCR and with the gold-standard algorithm (microscopy at birth and 2 months and serological study several months later). We screened pregnant women from two hospitals in the Bolivian Gran Chaco province, and those who were seropositive for T cruzi were offered the opportunity for their newborns to be enrolled in the study. Newborns were tested by microscopy, LAMP, and PCR at birth and 2 months, and by serology at 8 months. Between April 23 and Nov 17, 2018, 986 mothers were screened, among whom 276 were seropositive for T cruzi (28·0% prevalence, 95% CI 25·6–31·2). In total, 224 infants born to 221 seropositive mothers completed 8 months of follow-up. Congenital transmission was detected in nine of the 224 newborns (4·0% prevalence, 1·9–7·5) by direct microscopy observation, and 14 more cases were diagnosed serologically (6·3%, 3·6–10·3), accounting for an overall vertical transmission rate of 10·3% (6·6–15·0; 23 of 224). All microscopy-positive newborns were positive by PrintrLab-LAMP and by PCR, while these techniques respectively detected four and five extra positive cases among the remaining 215 microscopy-negative newborns. The PrintrLab-LAMP yielded a higher sensitivity than microscopy-based analysis. Considering the simpler use and expected lower cost of LAMP compared with PCR, our findings encourage its evaluation in a larger study over a wider geographical area. Inter-American Development Bank.