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

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

Pathogen disgust sensitivity protects against infection in a high pathogen environment

“…Therefore, the variables included in our Disgust questionnaire are not primary pathways of STH transmission. Analyses of larger datasets collected after this study also show that parasite load varies by region and community, likely due to variation in market integration-related hygiene/sanitation, infrastructure, and environmental factors, like water source (50)(51)(52). The present study supports this finding, with Parasites clustering strongly at the community level.…”

“…Stool Collection and Analysis. Fresh stool samples were collected and processed based on methods previously described (50)(51)(52). For each specimen, a single Kato-Katz thick smear (Vestergaard Frandsen) ( 88) was examined microscopically by a trained observer (T.J.C.-R.).…”

“…Individuals living in the Cross Cutucú region tend to have higher prevalence and intensity of STH infection (50,51). More market-integrated housing, particularly floor type (i.e., wood versus dirt) and water access (i.e., piped/well versus river/stream), are associated with reduced STH burden (52) and are more common in the Upano Valley. Additionally, more modern housing and reduced engagement in traditional subsistence activities are linked to less-diverse intestinal microbiota (53).…”

Low prevalence of anemia among Shuar communities of Amazonian Ecuador

“…Reliance on foraging, fishing, and hunting vary but are generally greater in the CC region (e.g., Liebert et al, 2013; Urlacher et al, 2016). Shuar exhibit high rates of stunting and infectious disease burden but with complex inter‐ and intra‐regional variation in prevalence (e.g., Blackwell, Pryor, Pozo, Tiwia, & Sugiyama, 2009; Gildner et al, 2016, 2020; Urlacher et al, 2018). Helminth infection rates of whipworm and roundworm are high (Cepon‐Robins et al, 2014; Gildner et al, 2016, 2020).…”

“…Data from Shuar of Amazonian Ecuador allow for an analysis of how market integration (MI: the degree of consumption from and production for a market economy; Lu, 2007) affects anemia rates (Liebert et al, 2013). Most Shuar live in two main regions of the Morona‐Santiago province in Ecuador: the Upano Valley (UV), which has greater access to healthcare facilities and market centers (Liebert et al, 2013; Urlacher et al, 2016), and Cross‐Cutucú (CC), which is more remote and generally associated with high rates of parasitic infection (Cepon‐Robins et al, 2014; Gildner et al, 2016, 2020).…”