Results from two cohort studies in Central Africa show that clearance of Wuchereria bancrofti infection after repeated rounds of mass drug administration with albendazole alone is closely linked to individual adherence

Abstract

Abstract Background Two community trials conducted from 2012 to 2018 in the Republic of Congo and the Democratic Republic of the Congo demonstrated the efficacy of semi-annual mass drug administration (MDA) with albendazole (ALB) alone on lymphatic filariasis (LF). However, a high inter-individual heterogeneity in the clearance of infection was observed. Methods We analyzed trial data to assess the effect of individual adherence to ALB MDA on clearance of circulating filarial antigenemia (CFA) and microfilaremia. Community residents were offered a single dose of ALB every 6 months and tested for LF with a rapid test for CFA at baseline and then annually. CFA test results were scored on a semi-quantitative scale. At each round, microfilaremia was assessed in CFA-positives. All CFA-positive subjects for whom at least one follow-up measure was available were included in the analyses. Parametric survival models were used to assess the influence of treatment adherence on LF infection indicators. Results Out of 2658 subjects enrolled in the trials, 394 and 129 were eligible for analysis of CFA and microfilaremia clearance, respectively. After adjusting for age, sex and initial CFA score, the predicted mean time for clearing CFA was shorter in persons who had taken 2 doses of ALB per year (3.9 years) than in persons who had taken 1 or 0 dose (4.4 and 5.3 years, P & .001 for both). A similar pattern was observed for microfilaremia clearance. Conclusions These results demonstrate a clear dose-response relationship for the effect of ALB on clearance of CFA and microfilaremia.