Doctoral Dissertation Improvement: Social change, parasite exposure and immune dysregulation: An evolutionary medicine approach

University Of Oregon Eugene, Eugene OR

Investigators

Abstract

Two recent hypotheses--the Hygiene Hypothesis and the Disappearing Microbiota Hypothesis--argue that the dramatic rise in allergies and autoimmune disorders in industrialized nations stems from decreased exposure to pathogens. These hypotheses posit a mismatch between contemporary lifestyles and the evolved biology of the human species. People living in developed nations such as the United States are experiencing reduced exposure to parasitic worms and bacteria, as well as overall changes to the microbial composition of the gut, compared to individuals living in less developed nations. These changes appear to be resulting in decreased immune stimulation and an increased vulnerability to allergy and autoimmune diseases, which are nearly absent in non-Western populations. The present dissertation study by doctoral student Tara Cepon (University of Oregon), under the supervision of Dr. James Snodgrass, tests both the Hygiene and Disappearing Microbiota Hypotheses among the Shuar, a forager-horticulturalist population from Amazonian Ecuador who are currently experiencing rapid yet uneven cultural change related to integration into the market-based economy. The project examines relationships among social/lifestyle factors, intestinal parasite composition, and immune function and dysregulation among three geographically separated Shuar communities experiencing different degrees of market involvement and related social change. Through household interviews, microscopic and molecular analyses of fecal samples, and biomarkers of immune function, the present project will shed light on patterns of parasite exposure and the role of humans as ecosystems for our parasitic residents, as well as the contribution that these residents make to immune development and function. This study also will advance knowledge of the health effects of cultural change by focusing needed attention on how environmental shifts affect infectious and autoimmune disease prevalence. Beyond these contributions, this study has important implications for public health policy, community outreach, international science partnerships, and education. The research increases our understanding of the effects of market-related changes on health variation among Shuar and, by extension, other populations undergoing cultural change. Further, it has the potential to provide insights that can be used for improving local and global health by identifying lifestyle factors to target when implementing policies to reduce infectious and chronic disease burden. Finally, this project will train a female scientist and will provide research opportunities for undergraduates.