A Preliminary Study to Compare Recombinase Polymerase Amplification-Lateral Flow and Quantitative PCR in the Detection of Cutaneous Leishmania in Communities from the Volta Region of Ghana.

Background: Leishmaniasis is a parasitic disease that mostly affects populations in tropical and subtropical countries. In Ghana, cutaneous leishmaniasis (CL) is the most common form of the disease affecting communities of the Volta Region. Conventional parasitological method (microscopy) is the commonly used test for CL diagnosis in many endemic countries, but has low sensitivity in chronic cases. Therefore, there is a clear need for a sensitive and easy-to-use point-of-care diagnostic method like an isothermal recombinase polymerase amplification-lateral flow (RPA-LF) test, suitable for use in austere and low-resource settings for the identification of CL cases. This study compared the efficacy of RPA-LF test with quantitative PCR (qPCR) in detecting Leishmania in suspected CL cases from the Volta Region. Methods: Twenty-five participants between 5 and 14 years were enrolled in the study from whom a total of 26 samples were obtained. Lesion samples were collected using FTA® filter papers applied to ulcerated lesions for molecular diagnosis. DNA isolated from filter papers was used for both the RPA-LF test and qPCR. Results: Twenty-two participants (88%) presented with one or two ulcerated active lesions per individual, while the rest of them had plaques or dried lesions. Among the 26 samples, 19/26 (73%) had concordant results when comparing the two diagnostic methods. Conclusion: Data from this study suggest that the RPA-LF test can be used in addition to a conventional parasitological diagnostic test (microscopy) to detect CL cases in communities of the Volta Region.

Recombinase polymerase amplification lateral flow dipstick (RPA-LF) detection of Babesia orientalis in water buffalo (Bubalus babalis, Linnaeus, 1758).

Babesiosis caused by Babesia orientalis, an intraerythrocytic apicomplexan protozoan, is one of the most important diseases for water buffalo in central and southern China, leading to huge economic losses, and its main diagnostic method is microscopic examination. In this study, a recombinase polymerase amplification - lateral flow dipstick (RPA-LF) assay, targeting the mitochondrial COXI gene of B. orientalis, was developed to detect B. orientalis in water buffalo. The RPA-LF assay was carried out as an isothermal reaction at 37 °C within 15 min. The specificity assay showed no cross-reactivity with other protozoa, and the sensitivity assay revealed the minimum detection limit was 0.25 parasite/µL, which was 40-fold more sensitive than that of conventional PCR (0.25 versus10 parasites/µL blood). Moreover, the RPA-LF method was successfully applied to test clinical samples, with no significant difference being observed between RPA-LF and conventional PCR results. Compared with conventional PCR, the novel RPA-LF method had the advantages of simple operation, short time, high sensitivity, and high specificity for B. orientalis detection, indicating the potential use of RPA-LF for rapid field detection of B. orientalis.