Market integration and soil-transmitted helminth infection among the Shuar of Amazonian Ecuador

PLoS One. 2020 Jul 31;15(7):e0236924. doi: 10.1371/journal.pone.0236924. eCollection 2020.

Abstract

Background: Soil-transmitted helminth (STH) infections have many negative health outcomes (e.g., diarrhea, nutritional deficiencies) that can also exacerbate poverty. These infections are generally highest among low-income populations, many of which are also undergoing market integration (MI; increased participation in a market-based economy). Yet the direct impact of MI-related social and environmental changes on STH infection patterns is poorly understood, making it unclear which lifestyle factors should be targeted to better control disease spread. This cross-sectional study examines if household infrastructure associated with greater MI is associated with lower STH burdens among Indigenous Ecuadorian Shuar.

Methods: Kato-Katz fecal smears were used to determine STH infection status and intensity (n = 620 participants; 308 females, 312 males, aged 6 months-86 years); Ascaris lumbricoides (ascarid) and Trichuris trichiura (whipworm) were the primary infection types detected. Structured interviews assessing lifestyle patterns (e.g., measures of household infrastructure) measured participant MI. Multilevel regression analyses and zero-inflated negative binomial regression models tested associations between MI measures and STH infection status or intensity, controlling for individual and community characteristics.

Results: Participants residing in more market-integrated households exhibited lower infection rates and intensities than those in less market integrated households. Parasite infection status and T. trichiura infection intensity were lower among participants living in houses with wood floors than those with dirt floors, while individuals using well or piped water from a spring exhibited lower A. lumbricoides infection intensities compared to those using river or stream water. Unexpectedly, latrine type was not significantly related to STH infection status or intensity. These results suggest that sources of exposure differ between the two helminth species.

Conclusions: This study documents associations between household measures and STH infection among an Indigenous population undergoing rapid MI. These findings can help healthcare programs better target interventions and reduce STH exposure among at-risk populations.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Animals
  • Ascariasis / epidemiology
  • Ascariasis / transmission
  • Ascaris lumbricoides / isolation & purification
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Ecuador / epidemiology
  • Family Characteristics
  • Feces / parasitology*
  • Female
  • Helminthiasis* / epidemiology
  • Helminthiasis* / transmission
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Population Groups / statistics & numerical data
  • Poverty / statistics & numerical data*
  • Prevalence
  • Risk Factors
  • Sanitation / statistics & numerical data
  • Soil / parasitology*
  • Surveys and Questionnaires
  • Toilet Facilities / statistics & numerical data
  • Trichuriasis / epidemiology
  • Trichuriasis / transmission
  • Trichuris / isolation & purification
  • Young Adult

Substances

  • Soil

Grants and funding

Support for the research was provided by the Wenner-Gren Foundation for Anthropological Research (Grant #9231, 8476, 8749); National Science Foundation (Doctoral Dissertation Improvement Grant #BCS-1650674, BCS-1341165); Lewis and Clark Exploration Grant; Ryoichi Sasakawa Young Leaders Fellowship Fund; the Center for Latino/a and Latin American Studies; and, the University of Oregon. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.