RESUMEN
Background: Worldwide, >654 million children live in regions where soil-transmitted helminth (STH) infections are endemic. These parasites cause a variety of symptoms, including anemia. Methods: In May 2023, fecal and blood samples were collected from children aged 6 to 11 years attending government run (public) elementary schools in the Simanindo and Ronggur Nihuta sub-districts of Samosir Island, Indonesia where a twice a year mass drug administration (MDA) program is currently in place. A questionnaire was administered to students' parents or adult family members on possible risk factors for STH infections. Qualitative data were collected through in-depth interviews and focus group discussions. Results: In total, 187 and 221 children in Simanindo and Ronggur Nihuta provided samples, respectively. The STH infection prevalence in Simanindo was 4.8% (9/187) and the infection prevalence in Ronggur Nihuta was 5.9% (13/221). In Simanindo, all infections were caused by Trichuris trichiura (n = 9), and in Ronggur Nihuta infections were caused by Ascaris lumbricoides (n = 6), Trichuris trichiura (n = 5), and A. lumbricoides + T. trichiura (n = 2). Three children had anemia but were negative for STH infections. While the results of the parent/adult questionnaires indicated access to a generally safe water supply and septic system, information from the in-depth interviews and focus groups revealed that the local water supply becomes greatly diminished during the dry season. Conclusions: While MDA has been shown to effectively control roundworms and hookworms, additional measures to control trichuriasis are needed. There is also a need for the government to invest in improving the public water supply infrastructure.