Diagnostic accuracy of point of care tests for Schistosoma haematobium: a systematic review

Abstract

Background: Urogenital schistosomiasis (UGS) caused by S. haematobium is a serious public health problem in Sub-Saharan Africa, associated with increased HIV acquisition and transmission in co-endemic areas of HIV and UGS. Accurate and accessible point-of-care testing for screening and diagnosis is vital for control and prevention of UGS in Sub-Saharan Africa. Point-of-care (POC) rapid diagnostic tests that have the merit of high sensitivity for both high and low parasite burden have been developed. These tests need to be assessed for their applicability in poorly resourced UGS-endemic areas so that control programs can be initiated. This diagnostic test accuracy (DTA) review evaluates the sensitivity and specificity of different direct POC, rapid (RDT) and field-applicable diagnostic tests. Objective: To assess the diagnostic accuracy of POC and rapid diagnostic tests for the direct diagnosis of urogenital schistosomiasis compared to laboratory-based reference tests in individuals from Africa, for improved screening and routine diagnosis in both endemic and non-endemic settings. Methods: Four databases were systematically searched for DTA studies on S. haematobium exposed patients in endemic and non-endemic settings from 2000-2022. Studies that compare the sensitivity and specificity of any direct POC or RDT for S. haematobium to a reference test were included. Using the variability of test thresholds, a bivariate or HSROC model was used in STATA 17 and Revman 5.3 software to calculate the summary ROC model for each eligible test. Heterogeneity tests and subgroup analyses for different reference standard comparators, age- groups and prevalence settings were conducted. Results were presented as percentages with a 95% confidence interval. Results: Thirty-three studies were evaluated, in which ten different POC and rapid tests were eligible, of which seven were included in a meta- analysis. Two field based molecular tests; loop mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) (sensitivity=99.9%, specificity=76.2% and sensitivity=94,1%, specificity=96.6% respectively) showed the most promise compared to a laboratory test. The immunochromatographic rapid diagnostic test (ICT-RDT) and S. mansoni cercarial transformation fluid RDT (SmCTF-RDT) serological tests are easy-to-use POC cassettes and have high sensitivity (96% and 98.4% respectively) but both require a centrifuge to obtain serum samples. Other serological tests: dipstick dye immunoassay (DDIA) and indirect haemagglutination assay (IHA) had lower sensitivities. The VI POC circulating cathodic antigen test (POC-CCA) (sensitivity=47%, specificity=71%) is not suitable for S. haematobium in prevalence settings of less than 50%. The up-converting phosphor lateral flow circulating anodic antigen test (UCP-LFCAA) (sensitivity=73%, specificity=72%), although laboratory intensive shows promise in endemic areas.