Challenges of onchocerciasis elimination in the Democratic Republic of Congo

BACKGROUND: Onchocerciasis remains a major public health problem in the Democratic Republic of Congo (DRC), one of the countries with the highest burden globally. Despite more than two decades of community-directed treatment with ivermectin (CDTI), progress toward elimination has been slower than expected. This review examines the main epidemiological, operational, and governance-related barriers that continue to hinder elimination efforts. METHODS: We conducted a structured narrative review informed by World Health Organization (WHO) frameworks for evaluating neglected tropical disease programmes. National programme reports, WHO technical documents, peer-reviewed publications, and grey literature produced between 2001 and 2020 were reviewed. Searches were performed in PubMed, Scopus, and Google Scholar using terms related to onchocerciasis, Onchocerca volvulus, Loa loa, ivermectin, CDTI, elimination, mapping, surveillance, and the DRC. Evidence was triangulated across epidemiological, operational, and governance domains. RESULTS: Major barriers include incomplete elimination mapping, large areas of unknown endemicity, and widespread co-endemicity with Loa loa, which limits the safe implementation of mass drug administration. Additional challenges include difficult terrain, insecurity, limited entomological capacity, programme interruptions, and concerns about sub-optimal ivermectin response. Operational weaknesses such as inadequate therapeutic and geographic coverage, delayed drug delivery, weak supervision, and attrition of community drug distributors further undermine CDTI effectiveness. Governance weaknesses, including delayed fund disbursement and insufficient accountability, also affect programme performance. CONCLUSION: Achieving elimination in the DRC will require completion of nationwide elimination mapping, strengthened epidemiological and entomological surveillance, improved governance, and financing mechanisms, and tailored strategies for Loa loa co-endemic and conflict-affected settings. Recent WHO guidance on elimination mapping and evolving strategies such as test-and-not-treat and moxidectin may help accelerate progress.