The Variation of Baboon Immunity with Age and Gender: What we can learn from Fecal Parasite Burden and Immunoglobulin Levels

Abstract

The immune system is an immensely complex entity that has been studied in many living systems. With pathogens and parasites present everywhere in the world around us, the ability of living organisms to mount an immune response against such infections is undoubtedly essential to survival and fitness. However, mounting an immune response does come at a cost. The more energy that is invested into maintaining immunity, the less can be invested into reproduction and other aspects of living and fitness as the organism ages and goes through life. This thesis study aims to look at how immunity changes over age. In this study, a cross-sectional analysis of two immunological parameters (parasite burden measured via fecal egg counts and fecal immunoglobulin A levels) over age were looked at for both male and female baboons of the Amboseli Baboon Research Project study population. The goal of the study was to see whether age is a significant predictor of these two immunological parameters, and to look at the variation of parasite fecal egg counts and fecal IgA across the different developmental stages of life. Results of the study show that while increasing age predicts a significant increase in parasite burden for both sexes, it does not predict significant changes in the fecal immunoglobulin A levels for either sex. From these results, we can speculate that the baboon population does not tend to increase immune resistance to intestinal parasite burden as it ages. This lack of mounting increased resistance then comes at the trade-off of increased parasitic burden over age. Results of the study also show that males tend to have a greater increase in parasite burden as they age in comparison to females. With baboons serving as a close animal model to the human population, the results of this thesis study has potential global health implications for the human population. The findings of this thesis study perhaps suggest that human populations faced with energy constraints and parasite exposure like the Amboseli baboons will also experience increased parasitic burden over age without developing a significant increase in immune resistance towards the parasitic burden