Soil-Transmitted Helminth Eggs Are Present in Soil at Multiple Locations within Households in Rural Kenya

PLoS One. 2016 Jun 24;11(6):e0157780. doi: 10.1371/journal.pone.0157780. eCollection 2016.

Abstract

Almost one-quarter of the world's population is infected with soil-transmitted helminths (STH). We conducted a study to determine the prevalence and location of STH-Ascaris, Trichuris, and hookworm spp.-egg contamination in soil within rural household plots in Kenya. Field staff collected soil samples from July to September 2014 from the house entrance and the latrine entrance of households in Kakamega County; additional spatial sampling was conducted at a subset of households (N = 22 samples from 3 households). We analyzed soil samples using a modified version of the US Environmental Protection Agency (EPA) method for enumerating Ascaris in biosolids. We found 26.8% of households had one or more species of STH eggs present in the soil in at least one household location (n = 18 out of 67 households), and Ascaris was the most commonly detected STH (19.4%, n = 13 out of 67 households). Prevalence of STH eggs in soil was equally likely at the house entrance (19.4%, N = 67) as at the latrine entrance (11.3%, N = 62) (p = 0.41). We also detected STH eggs at bathing and food preparation areas in the three houses revisited for additional spatial sampling, indicating STH exposure can occur at multiple sites within a household plot, not just near the latrine. The highest concentration of eggs in one house occurred in the child's play area. Our findings suggest interventions to limit child exposure to household soil could complement other STH control strategies.

MeSH terms

  • Adolescent
  • Animals
  • Child
  • Child, Preschool
  • Family Characteristics*
  • Female
  • Helminthiasis / epidemiology*
  • Helminthiasis / parasitology
  • Helminthiasis / transmission*
  • Helminths*
  • Humans
  • Kenya / epidemiology
  • Male
  • Parasite Egg Count
  • Prevalence
  • Rural Population*
  • Soil / parasitology*

Substances

  • Soil

Grants and funding

Funding was provided in the form of student fellowships to Lauren Steinbaum by the National Science Foundation Graduate Research Fellowship Program (1000160864; www.nsfgrfp.org), the U.S. Agency for International Development Research and Innovation Fellowships Program (2000004603, www.usaid.gov/RIFellowships), and the Stanford Center for African Studies Summer Graduate Student Research Grant Program (http://africanstudies.stanford.edu/fellowships/research_and_language_fellowships). This study was made possible by utilizing the data collection infrastructure established by the WASH Benefits Kenya study (the WASH Benefits study is supported by a grant from the Bill and Melinda Gates Foundation to UC Berkeley). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.