Treatment efficacy and re-infection rates of soil-transmitted helminths following mebendazole treatment in schoolchildren, Northwest Ethiopia

BACKGROUND: Transmission of soil-transmitted helminth (STH) infection remains high in Ethiopia. This study aimed at assessing the therapeutic efficacy of mebendazole against soil-transmitted helminths and determining the re-infection rates of the parasites among schoolchildren in Northwest Ethiopia. METHODS: A school-based cross-sectional study was conducted. Data was collected using a structured questionnaire. Stool specimens were examined using direct wet mount microscopy and Kato-Katz methods. Schoolchildren who tested positive for soil-transmitted helminths were treated with 500 mg single-dose of mebendazole. Cure and egg reduction rates were evaluated 2 to 3 weeks post treatment. Moreover, the re-infection rate of these parasites among those who were cured was determined 1 year after treatment. Data were analyzed using SPSS version 20. P value < 0.05 was considered as statistically significant. RESULT: A drug efficacy study was conducted on 62, 52, and 14 children infected by Ascaris lumbricoides (A. lumbricoides), hookworm, and Trichuris trichiura (T. trichiura), respectively. The cure rates (CR) of mebendazole against A. lumbricoides, hookworm, and T. trichiura were found to be 96.9%, 23.1%, and, 28.6%, respectively. The egg reduction rate (ERR) of A. lumbricoides was found to be 99.6% whereas 49.6% and 56.3% were reported for hookworm and T. trichiura, respectively. Eighty schoolchildren who were treated and cured from any STH infections were included for the determination of re-infection rate. Out of 80 children, 36.3% (29/80) were found to be re-infected after 1 year: 22 (75.9%), 6 (20.7%), and 1 (1.3%) of study participants were re-infected with A. lumbricoides, hookworm, and both infections, respectively. All re-infections were grouped under the “light infection” category. CONCLUSION: Mebendazole was found to be highly effective against A. lumbricoides, but had relatively low efficacy against hookworms and T. trichiura. These results bring into question the use of mebendazole in STH mass drug administration (MDA) programs in this region if albendazole, a drug with higher efficacy against hookworms, is available. Moreover, a significant number of treated children were re-infected with either or both of A. lumbricoides or hookworms 1 year after treatment emphasizing the need for better integrated intestinal helminthiasis control measures.