Diagnostic performance of a novel point-of-care test for the diagnosis of visceral leishmaniasis in Sudan: A Comparative Accuracy Study

Abstract

East-African countries suffer from a high incidence of Visceral Leishmaniasis (VL). Despite the availability of several diagnostic tests for VL, diagnosis remains a challenge in these countries. Due to the inefficiency of current diagnostics, a novel rapid diagnostic test (RDT) (INgezim Leishma-CROM) based on a recombinant multi-epitope kinesin antigen, rKLi8.3, was compared with the currently used rK39 RDT (IT-LEISH) in Eastern Sudan. Methods This study enrolled 107 VL suspects who attended a health centre in Gedaref between October 2022 and June 2023. Diagnostic accuracy was assessed by comparing the performance of the new index test (INgezimLeishma-CROM) with the comparator test (IT-LEISH) and parasitological examination as reference standard. Results Of 107 VL suspects screened by parasitological examination, 77 VL patients were smear positive and 30 were smear negative. Independent serological testing of these patients using INgezim Leishma-CROM showed a sensitivity of 98.7% [95% CI 92.23-99.97] and specificity of 92.5% [95% CI 75.71-99.09]. For IT-LEISH, both sensitivity [95% CI 84.39-97.20] and specificity [95% CI 75.71-99.09] were 92.5%. INgezim Leishma-CROM demonstrated increased diagnostic accuracy (97.2%) compared to IT-LEISH RDT (92.5%). Both RDTs gave positive results in 2 cases from the smear negative group that were previously treated for VL. All other non-VL cases (malaria, typhoid, brucellosis) were negative in both RDTs, showing 100% specificity, while VL patients co-infected with malaria were positive in both tests. Within the smear-negative group, 3 VL symptomatic cases that had been previously treated but still show clinical signs were all positive with INgezim Leishma-CROM but only 2 cases were positive with IT-LEISH.