A cross-comparison of enteric pathogen prevalence and patterns of infection within and between wild-living Cross River gorillas (Gorilla gorilla diehli) and eastern chimpanzees (Pan troglodytes schweinfurthii) Open Access

Abstract

Emerging infectious diseases represent a serious threat to biodiversity conservation and global health. This is of particular concern for the great ape species, whose close evolutionary relatedness to humans puts them at high risk for cross-species transmission events. As humans and great apes increasingly come into contact with one another, the potential for pathogen exchange and disease emergence is heightened—threatening both great ape conservation and human health. Given what we know about shared susceptibility and pathogen transmission between humans and great apes, it is vital to understand baseline information on what pathogens exist in wild ape populations. Few studies have broadly investigated the pathogen communities of great apes, and those that have often tend to be limited in scope. The goals of this study were therefore to survey wild Cross River gorillas (Gorilla gorilla diehli, critically endangered) and eastern chimpanzees (Pan troglodytes schweinfurthii, endangered) for an array of viral, parasitic, and bacterial enteric pathogens. A novel real-time PCR diagnostic platform, The TaqMan Array Card, was used to noninvasively screen fecal samples for 39 enteric pathogen-specific gene targets in these two great ape subspecies. Pathogen prevalence, as well as patterns of infection and coinfection, were compared between species and within species among gorilla and chimpanzee populations. All gorilla individuals and approximately 70% of chimpanzee individuals were infected with at least one enteric pathogen. Of the infected gorillas, 44% showed single infections and 56% showed coinfections. Of the infected chimpanzees, 51% showed single infections and 49% showed coinfections. Adenovirus and Cryptosporidium parvum were the most common pathogens detected in both species. Proportionally, gorillas harbored more parasitic and bacterial infections than chimpanzees. These findings offer a comparative look into the pathogen profiles of a highly elusive and understudied great ape (the Cross River gorilla) and a habituated and extremely well-known great ape (the eastern chimpanzee). This study highlights the need for further research in order to better define health risks, monitor populations, and guide management actions to protect human and great ape health. 

Table of Contents

1. Introduction.................................................................................................................. 1-7

1.1. Emerging Infectious Diseases....................................................................... 1-2

1.2. Disease in Great Ape Conservation.................................................................. 2

1.3. Great Ape Pathogen Surveillance................................................................. 3-5

1.4. Cross River Gorilla....................................................................................... 5-6

1.5. Eastern Chimpanzee...................................................................................... 6-7

2. Goals and Hypothesis...................................................................................................... 7

3. Materials and Methods............................................................................................... 7-16

3.1. Cross River Gorilla Study Site...................................................................... 7-9

3.2. Eastern Chimpanzee Study Site.................................................................. 9-10

3.3. Sample Collection..................................................................................... 11-12

3.4. TaqMan Array Card Diagnostic Platform................................................. 12-13

3.5. Molecular Analysis................................................................................... 13-14

3.6. Analysis..................................................................................................... 14-16

4. Results...................................................................................................................... 16-19

4.1. Infection and Pathogen Prevalence........................................................... 16-17

4.2. Patterns of Coinfection............................................................................. 17-19

5. Discussion................................................................................................................ 19-25

6. References................................................................................................................ 26-39

7. Tables....................................................................................................................... 40-47

7.1. Table 1............................................................................................................ 40

7.2. Table 2............................................................................................................ 41

7.3. Table 3............................................................................................................ 41

7.4. Table 4............................................................................................................ 42

7.5. Table 5............................................................................................................ 42

7.6. Table 6............................................................................................................ 42

7.7. Table 7............................................................................................................ 43

7.8. Table 8............................................................................................................ 44

7.9. Table 9............................................................................................................ 45

7.10. Table 10........................................................................................................ 45

7.11. Table 11........................................................................................................ 46

7.12. Table 12........................................................................................................ 47

About this Master's Thesis

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School	Laney Graduate School
Department	Environmental Sciences
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Biology, Ecology Biology, Conservation Environmental Health
Keyword	gorilla zoonoses Chimpanzee emerging infectious diseases disease ecology
Committee Chair / Thesis Advisor	Dr. Thomas Gillespie, Emory University
Committee Members	Dr. Uriel Kitron , Emory University Dr. Lance Gunderson, Emory University

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