Latrine use, boiled water, and bed nets: associations between biomarkers of immune status and public health in a subsistence population

This study examines associations between clean water, sanitation, mosquito net usage, and immune biomarkers among the Tsimane, a remote subsistence population of forager-horticulturalists with a high pathogen load. Interviews with heads of household (n=710, aged 18-92, median age 40 years) were conducted to ascertain household water sources, ownership and usage of mosquito nets, and latrine use. In this sample, 21% of households used latrines, 20% always boiled their water, and 85% used mosquito nets. Regression models estimate their associations biomarkers of pathogen exposure, including white blood cell count (WBC), hemoglobin (Hb), eosinophils, and sedimentation rate (ESR). Controlling for age, sex, and distance from the closest market town, latrine use (Std. β = -0.11, p= 0.017) and boiling water (Std. β = -0.08, p= 0.059) are associated with lower WBCs. Latrine use is marginally associated with higher hemoglobin (Std. β = 0.09, p= 0.048), but not boiling water (p= 0.447). ESR trends toward lower levels for households that always boil water (Std. β= -0.09, p= 0.131), but is not associated with latrine use (p=0.803). Latrine use was significantly associated with lower eosinophil counts (Std. β= -0.14, p=0.013), but not boiling water (p=0.240). Mosquito nets are not associated with any of these biomarkers. Both boiling water and latrine use are associated with better health outcomes in this sample. These results suggest that scarce public health resources in rural subsistence populations without malarial risk may wish to prioritize boiling water and latrine use to improve health outcomes.