Circulating Epstein–Barr Virus Antibody Levels as a Biomarker of Socioecological Adversity in Amazonian Ecuador

Objectives: Circulating Epstein–Barr virus antibodies (EBV-Ab) are used as a biomarker of chronic stress in high-income settings, but their relevance in environments with a high burden of infectious disease, nutritional constraints, and limited resources is less clear. We investigated EBV-Ab as a biomarker of adversity in a setting where local ecology and economy may affect immune development differently than in wealthy countries. Methods: We measured EBV-Ab in finger-prick dried blood spots collected from Indigenous Shuar (n = 433) and non-Indigenous Colonos (n = 84) ranging from < 1 to 87 years old in Amazonian Ecuador. For a subset of adults (≥ 15 years, n = 210), we collected socioeconomic information (income, education, and occupation) and assessed household-level market integration. We determined the most important predictors of EBV-Ab for adults and children using multi-model averaging of linear regression models. Results: Male children (< 15 years) had lower EBV-Ab than female children (model averaged β [SE]: −0.238 [0.066]). For adults, Shuar had higher EBV-Ab than Colonos (model averaged β [SE]: 0.235 [0.113]), and high systolic blood pressure was an important predictor of elevated EBV-Ab (model averaged β [SE]: 0.088 [0.047]). Individuals who reported unpaid domestic work as their primary occupation had higher EBV-Ab than agricultural workers (model averaged β [SE]: 0.302 [0.113]). Individuals living in houses with more market-sourced infrastructure had lower EBV-Ab (model averaged β [SE]: −0.088 [0.068]). Conclusions: Circulating EBV-Ab may capture context-specific aspects of socioecological adversity in Amazonian Ecuador, highlighting disparities in EBV-Ab between Indigenous and non-Indigenous Ecuadorians and differences in immune function related to market integration.