Background Targeted mass drug administration (MDA) of single-dose albendazole to the at-risk population as preventive chemotherapy or deworming is recommended by WHO to halt transmission of soil-transmitted helminth (STH) in endemic countries. We assessed the effectiveness of single-dose albendazole distributed through a school-based MDA program against hookworm, ascaris lumbricoides, and trichuris trichiura STH infection.

Methods 984 STH-positive school children from two rural woredas in southern Ethiopia were enrolled. Stool samples were examined before MDA and at weeks 4 and 8 post-MDA. Efficacy was assessed using cure rate (CR) and egg reduction rate (ERR).

Results The proportion of children who were cured of any STH parasite at week 4 and week 8 of post-MDA were 46% and 43.3%. The CR was 97.2%, 71.5%, and 49.5% for hookworm, ascaris lumbricoides, and trichuris trichiura respectively at week 4 post-MDA. The ERR at week 4 was 98.8%, 84.5%, and 68.3% for hookworm, ascaris lumbricoides and trichuris trichiura respectively. The observed CR (97.2%) and ERR (98.8%) for hookworm were above the WHO efficacy threshold (CR ≥95%, ERR ≥90%). However, CR (71.5%) and ERR (84.5%) for ascaris lumbricoides were lower than the WHO efficacy threshold (>95%) indicating a reduced efficacy. The CR (49.5%) for trichuris trichiura was below the WHO efficacy threshold (>50%) but the ERR (68.3%) was above the WHO efficacy threshold (>50%). The CR of ascaris lumbricoides in younger children was significantly lower compared to the older children (64.4% versus 74.2%, p=0.006).

Conclusion We found a reduced efficacy of single-dose albendazole against ascaris lumbricoides and doubtful for trichuris trichiura but efficacious in treating hookworm. Therefore, alternative treatment options are needed for the effective elimination of STH as a public health problem by 2030.

Funding: This study was supported by the EDCTP2 program as part of the PROFORMA project (Grant number CSA2016S-1618).