Regional variation in Ascaris lumbricoides and Trichuris trichiura infections by age cohort and sex: effects of market integration among the indigenous Shuar of Amazonian Ecuador

Abstract

BackgroundSoil-transmitted helminth (STH) infection peaks during childhood and varies by sex. The impact of market integration (MI) (increasing production for and consumption from a market-based economy) on these infection patterns, however, is unclear. In this study, STH infection is examined by sex and age among indigenous Shuar inhabiting two regions of Amazonian Ecuador: (1) the modestly market-integrated Upano Valley (UV) and (2) the more traditional Cross-Cutucú (CC) region.MethodsKato-Katz fecal smears were examined for parasite presence and infection intensity. Factorial ANOVAs and post hoc simple effects analyses were performed by sex to compare infection intensity between regions and age categories (infant/child, juvenile/adolescent, adult).ResultsSignificant age and regional differences in Ascaris lumbricoides and Trichuris trichiura infection were detected. Overall, infants/children and juveniles/adolescents displayed higher parasite loads than adults. CC females exhibited higher A. lumbricoides loads than UV females, while the opposite pattern was observed for T. trichiura infection in males.ConclusionsRegional infection patterns varied by sex and parasite species, perhaps due to MI-linked environmental and lifestyle changes. These results have public health implications for the identification of individuals at risk for infection and contribute to ongoing efforts to track changes and alleviate STH infection in indigenous populations undergoing MI.

Soil‐transmitted helminth infection and intestinal inflammation among the Shuar of Amazonian Ecuador

“…This study presents preliminary but unique data on relationships between STH infection and intestinal inflammation using FC among a small sample of Shuar children and adults. The Shuar are an indigenous population from Amazonian Ecuador with previously documented moderate to high rates of STH infection (Cepon-Robins et al, 2014;Gildner et al, 2016).…”

“…However, Shuar are currently experiencing increasingly rapid but widely variable market integration (i.e., the degree of production for and consumption from marketbased economies) within and across communities. Market integration among the Shuar has increased variation in several aspects of infrastructure and lifestyle, including in healthcare, house construction, sanitation, and exposure to pathogens (e.g., STHs; Cepon-Robins et al, 2014;Gildner et al, 2016;Liebert et al, 2013;Stagaman et al, 2018;Urlacher et al, 2016;Urlacher et al, 2018).…”

“…Research by the Shuar Health and Life History Project (SHLHP) has documented high prevalence of STH infection among the Shuar (Cepon-Robins et al, 2014;Gildner et al, 2016), with children having significantly higher STH infection rates and intensities than adults (Cepon-Robins et al, 2014;Gildner et al, 2016). Furthermore, biomarkers associated with the adaptive immune response to STH infection, like immunoglobulin E (IgE), peak mid-childhood (about 10 years of age) (Blackwell et al, 2011), indicating that childhood is an important time for macroparasite exposure and associated immune system development (Blackwell et al, 2011;Cepon-Robins et al, 2014;Gildner et al, 2016). Furthermore, Shuar who live in rural villages characteristic of most of the population, exhibit no evidence of chronic low-grade systemic inflammation measured via C-reactive protein in adulthood, suggesting that elevated systemic inflammation with age is not com-…”

“…First-morning stool samples were collected and analyzed in the field for presence and intensity of species-specific STH infection based on methods reported previously by the SHLHP (Cepon-Robins et al, 2014;Gildner et al, 2016). Two species of STH were detected: Ascaris lumbricoides (large roundworm) and Trichuris trichiura (whipworm).…”

“…The Shuar are an indigenous population from Amazonian Ecuador with previously documented moderate to high rates of STH infection (Cepon-Robins et al, 2014;Gildner et al, 2016). The Shuar are an indigenous population from Amazonian Ecuador with previously documented moderate to high rates of STH infection (Cepon-Robins et al, 2014;Gildner et al, 2016).…”