Molecular-based assessment of the efficacy of anthelminthic combination regimens for the treatment of Strongyloides stercoralis in Gabon

Purpose: To assess the efficacy of three proposed anthelminthic combination regimens for the treatment of strongyloidiasis using real-time polymerase chain reaction (real-time PCR) diagnostic method. Methods: We conducted an interventional randomized assessor-blinded clinical trial in which participants positive for strongyloidiasis were treated with three different therapeutic regimens: albendazole (ABZ) once a day for three days, and ABZ on days 1 and 3 associated with mebendazole (MBZ) or pyrantel (PYR) on day 2, respectively. All participants were seen after treatment for drug efficacy assessment. Microscopy methods and real-time PCR analysis were used for the diagnosis of strongyloidiasis, and the proportions of positive cases were compared between the two tests. Cure rate (CR) was reported to describe the efficacy of each treatment regimen. Risk factors for strongyloidiasis were assessed. Results: Fifty-nine of the 272 participants included in the study were positive for S. stercoralis infection at baseline as determined by either microscopy and/or PCR. The PCR-positive cases were 3.92 times higher than microscopy positive cases. The microscopy- and PCR-based corrected CRs were 100% and 68% (95%CI: 53–81), respectively. The CR was greater for the ABZ-ABZ-ABZ (77%; 95%CI: 55–92) than for the ABZ-MBZ-ABZ (69%; 95%CI: 39–91) or ABZ-PYR-ABZ (50%; 95%CI: 21–79) regimens, but the difference was not statistically significant. None of the factors investigated (age, sex, or location) were associated with either being infected with S. stercoralis in our cohort or being cured. Conclusion: Our findings indicate that on the one hand, the need for a more sensitive method than current microscopy for the diagnosis of strongyloidiasis and on the other hand ABZ alone repeated over three days has better efficacy for the treatment of strongyloidiasis than alternating ABZ with MBZ or PYR for the same period of treatment. However, its efficacy remains limited, raising the necessity for the development of alternative treatments. Clinical trial: Registered at ClinicalTrials.gov (NCT04326868) on March 04, 2020.