Researchers collected fresh stool samples from the children and examined them using direct saline smears, iodine smears and Kato-Katz thick smears. These methods detected the parasite categories reported in the study and allowed investigators to estimate infection prevalence and egg density. The infected child had 1,080 eggs per gram of T. trichiura in stool. Investigators also used an interviewer-administered questionnaire to collect information on sociodemographic characteristics, sanitation, hygiene and recent anthelmintic treatment. Of the 273 participants, 166, or 60.8%, reported receiving an anthelmintic drug recently, but none reported receiving recent lymphatic-filariasis mass drug administration or antifilarial treatment. Every participant reported washing their hands before meals and after using the toilet.

The 2023 findings were compared descriptively with surveys conducted in Hamugewatta from 2001 to 2006. In Sri Lanka, albendazole was co-administered with diethylcarbamazine as part of the national lymphatic filariasis elimination programme, and the researchers noted that this combination may have had ancillary effects on soil-transmitted helminth transmission. The comparison nevertheless has substantial limitations. A 17-year surveillance gap separated the earlier survey period from the 2023 assessment, the populations examined at the two time points differed, and additional deworming and improvements in sanitation and hygiene occurred during the interval. As a result, the low prevalence observed in 2023 cannot be attributed to the original mass drug administration programme alone.

Soil-transmitted helminths remain a public-health concern in settings with inadequate sanitation and hygiene. The three principal types identified in the study background are Ascaris lumbricoides, Trichuris trichiura and hookworms. Their microscopic eggs or larvae can enter soil contaminated with human feces; infection may occur when people swallow eggs on dirty food or unwashed hands, or when active larvae pass directly through the skin. The survey therefore measured a low prevalence of these infections in one sentinel community and a small number of reported preventive behaviors at the time of data collection. It did not directly evaluate sanitation coverage, program coverage, transmission patterns or the reasons for the historical difference.

The study demonstrates a very low measured burden among the sampled children in July 2023, but its cross-sectional design does not establish whether transmission has been eliminated or whether the result can be generalized to other communities or age groups. The historical and contemporary observations also come from surveys with different populations, further limiting direct inference about change over time. The investigators concluded that continued surveillance is warranted to determine which factors are sustaining the low soil-transmitted helminth burden. Their evidence supports ongoing measurement of prevalence in the sentinel setting, while leaving the independent effects of the lymphatic-filariasis programme, subsequent deworming, sanitation and hygiene unresolved.

Subject of Research: Long-term soil-transmitted helminth prevalence among children after mass drug administration in Sri Lanka

Article Title: Soil-transmitted helminth prevalence in a Sri Lankan sentinel community 22 years after the initiation of mass drug administration: a cross-sectional survey

Article References: Liyanapathiranage, D. A., Fernando, B. N. T., & Yahathugoda, T. C. (2026). Soil-transmitted helminth prevalence in a Sri Lankan sentinel community 22 years after the initiation of mass drug administration: a cross-sectional survey. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14364-6

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14364-6

Keywords: soil-transmitted helminths, Sri Lanka, mass drug administration, albendazole, diethylcarbamazine, lymphatic filariasis, Trichuris trichiura, child health, sanitation, hygiene, cross-sectional survey, Soil-transmitted