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"Make new friends and keep the old? Parasites, immune function, health, and changing market integration in Amazonian Forager-Horticulturalists" by Aaron Blackwell

Friday, January 27, 2012
12:00 AM
411 West Hall

As traditional populations become more integrated with national and transnational economies and cultures, factors such as diet, access to resources, disease exposure, and family composition all change. Within population and cross-cultural comparisons are needed to understand how these changes are integrated, and how they affect the health and well-being of these populations. In this talk I will discuss how life history theory provides a framework for understanding trade-offs and changes, and discuss my work among two Amazonian groups, the Shuar of Ecuador and the Tsimane of Bolivia.
As traditional populations become more integrated with national and transnational economies and cultures, factors such as diet, access to resources, disease exposure, and family composition all change. Within population and cross-cultural comparisons are needed to understand how these changes are integrated, and how they affect the health and well-being of these populations. In this talk I will discuss how life history theory provides a framework for understanding trade-offs and changes, and discuss my work among two Amazonian groups, the Shuar of Ecuador and the Tsimane of Bolivia. In particular, I examine infection with intestinal worms (helminths) as a critical factor that affects the development of immune function, children’s growth, and inflammatory or auto-immune diseases common in Western populations, a suggestion known as the “hygiene hypothesis”. I use ELISA to assess antibody levels, and flow cytometry to count white blood cell populations. My results show that a particular class of antibody (IgE) is highly elevated in parasitized populations, and that IgE levels are associated with poorer growth in Shuar, Tsimane, and the United States. In the Tsimane, natural killer cells are elevated compared to other populations, while helper T-cells are suppressed. Helminth infection is also associated with a higher prevalence of respiratory diseases in Tsimane children, but is protective against arthritis and inflammatory pain in older adults. These results suggest helminths impose significant costs on traditional populations and also support the “hygiene hypothesis”, suggesting that many of the health differences observed between Western and traditional populations may be tied to parasitic infection or lack thereof.