Erica Grant

Project title: A comparative analysis of gut microbiota on the human-macaque interface in Northeast Thailand

Degree: MPH | Program: One Health (ONE) | Project type: Thesis/Dissertation
Completed in: 2018 | Faculty advisor: Peter Rabinowitz


Traditional zoonotic disease research efforts centered on detection of high profile pathogens may miss opportunities to understand broader microbial transmission dynamics between humans, animals, and the environment. The Global Assessment of Zoonotic and Environmental Risks (GAZER) platform seeks to address this knowledge gap by examining overlaps of bacterial microbiome communities between humans, animals, and environments in settings where interaction with animals is high and potential for human health impacts of this contact are greater. This thesis presents data from Maha Sarakham, Thailand, where a growing population of long-tailed macaques (Macaca fascicularis) in the Kosumpee Forest Park interface with residents of the adjacent village. In particular, community members working in or near the park experience a high level of direct and indirect contact with macaques through feeding as well as aerosols of macaque feces during cleaning. Workers were surveyed to characterize tasks that contribute to exposure and other dietary or lifestyle factors that influence gut microbiome composition. We employed comparative microbiome analysis based on the V4 region of the 16S rRNA gene from DNA extracts of stool samples to assess the degree of similarity between gut bacterial communities and potential for pathogen transmission between macaques and workers. Fecal samples were collected from humans (exposed, n=12; control, n=6) and macaques (exposed, n=8; control, n=4) using the OMNIgene.GUT kit and sequenced on the Illumina HiSeq platform. SourceTrackers was the primary tool to assess degree of microbial sharing between humans and macaques and revealed no significant difference in microbial sharing with macaques between exposed and control humans. Variance detected in PCoA visualizations of the unweighted UniFrac distance were tested using adonis and betadisper to investigate the potential role of the Anna Karenina principle (AKP). Exposed macaque samples exhibited significantly greater dispersion than controls (p<0.01). Human samples had homogenous dispersion but different spatial medians between groups (p<0.03), implying a shift in microbial composition. Alterations in gut microbiota of exposed macaques highlights the potential for increased susceptibility to other diseases. Task observations and surveys assessing knowledge, attitudes, and practices among workers revealed opportunities to employ of protective measures or training to reduce exposure to occupational hazards. This information can also be used to mitigate negative aspects of contact between humans and macaques in order to optimize the health of both populations. URI