Assessment of the diagnostic accuracy and relevance of a novel ELISA system developed for seroepidemiologic surveys of Helicobacter pylori infection in African settings

Beside diagnostic uncertainties due to the lack of a perfect gold standard test for Helicobacter pylori infection, the diagnosis and the prevalence estimation for this infection encounter particular challenges in Africa including limited diagnostic tools and specific genetic background. We developed and evaluated the accuracy of an enzyme-linked immunosorbent assay (ELISA) system tailored for H. pylori genetics in Africa (HpAfr-ELISA). Strains belonging to main genetic populations infecting Africans were exploited as sources for whole-cell antigens to establish in-house the ELISA system. A phase II unmatched case-control study explored the diagnostic accuracy of the HpAfr-ELISA using a training set of samples collected from dyspeptic patients from Kinshasa, the Democratic Republic of Congo (DRC) who had been tested with invasive standard tests (i.e., histology, culture, and rapid urease test) in 2017. Then the assay was cross-validated through a community-based survey assessing the prevalence of H. pylori and associated factors in 425 adults from Mbujimayi, DRC in 2018. Bayesian inferences were used to deal with statistical uncertainties of estimates (true prevalence, sensitivity, and specificity) in the study population. At its optimal cut-off-value 20.2 U/mL, the assay achieved an estimated sensitivity of 97.6% (95% credible interval [95%CrI]: 89.2; 99.9%) and specificity of 90.5% (95%CrI: 78.6; 98.5). Consistent outcomes obtained at repeated tests attested the robustness of the assay (negative and positive agreements always > 70%). The true prevalence of H. pylori was estimated 53.8% [95%CrI: 42.8; 62.7%]. Increasing age (adjusted odds ratio [aOR] > 1.0 [95% confidence interval (CI): > 1.0; 1.1]; p
Author summary Enzyme-linked immunosorbent assay (ELISA) systems are useful tools for mass screening of Helicobacter pylori infection but their use encounters important challenges in Africa. This is mainly due to the specific genetic background of African H. pylori that may jeopardize the accuracy of currently available ELISA kits. In this study, we developed a new ELISA system, i.e. HpAfr-ELISA, based on pooled antigens of H. pylori that represent main genetic populations colonizing Africa. This new assay could be validated analytically using training samples collected in H. pylori positive and negative patients from the Democratic Republic of Congo (DRC). Then, the tool was successfully applied to a real-world community-based mass survey aiming at assessing the epidemiology of H. pylori in a rural area of the DRC. The characteristics of the HpAfr-ELISA assay indicated good robustness and high performances for detection of H. pylori. Statistical modeling enabled estimating the true latent prevalence of H. pylori infection and identifying factors predicting the exposition to the infection in the study population. This outcome will be useful for drawing efficient health policies and optimally allocating available resources to fight the H. pylori infection and related complications (e.g., gastric cancer) in the study area and globally in Africa.