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Examining Microbial Transfer Between Human and Non-Human Primates Using a One Health Approach

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July 2024

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2025-07-01

Authors

Smith, Dejah

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East Carolina University

Abstract

The health of humans, wildlife, plants, and their environments are interconnected, and this concept is fundamental promoting public health and conservation goals globally. The One Health approach defines the relationship of humans, plants, animals and our shared environments, positioning health at the core. This approach aids conservation management as facilities can look at health holistically, focusing not only on the health of the captive populations but also of the staff, volunteers, and the public. This is particularly important for the conservation of endangered species, such as lemurs. In Madagascar, lemur populations represent 20% of the worlds primate species and are endangered due to habitat fragmentation, deforestation, and anthropogenic factors. Captivity gives endangered populations a chance at rehabilitation and humans the opportunity to observe and learn from their behaviors, physiology, and development. Although captivity holds many benefits, we must think about how factors introduced by conservatory settings influence the health of captive animals and the humans who interact with them. Past studies have documented the transfer of microbes is documented to occur between humans and their pets. In this study, I examined the extent to which microbiome exchange occurred between human and non-human primates observed at the Duke Lemur Center (DLC) in Durham, North Carolina, USA. I hypothesized that (i) lemurs exposed to human microbiomes frequently (i.e., daily) and housed in captive only settings will exhibit altered gut microbial compositions and higher microbial diversity of human associated taxa than free-ranging lemurs that interact rarely with humans and maintain spatial proximity or no human contact. I also hypothesized that (ii) humans working in Duke Lemur Center departments with high levels of contact between NHPs will harbor an altered skin microbiome, composed of bacterial taxa associated with lemur species. To test this hypothesis, I collected fecal samples from four lemur populations, which included blue-eyed black lemurs (Eulemur flavifrons), Coquerel’s sifakas (Propithecus coquereli), crowned lemurs (Eulemur coronatus), and ring-tailed lemurs (Lemur catta). This research was approved by the East Carolina University’s Institutional Animal Care and Use Committee (IACUC) protocol number: AUP#P110. Human forehead and hand skin swab samples from 13 interns over five timepoints were provided voluntarily from the DLC summer interns who worked in various departments across the facility. These protocols were approved by East Carolina University’s Intuitional Review Board (#UMCIRB 22-000802). The gradient of lemur-human interaction intensity across DLC department was done to ensure a variety of frequency of interaction with the lemur populations. There were seven husbandry interns, four research interns, one education intern and one paleo-primatology intern. I extracted genomic DNA from human skin and lemur fecal samples and conducted 16S rRNA gene PacBio HiFi long-read sequencing. Results showed that human-associated taxa were observed to a greater extent in the gut microbiomes of enclosed lemurs where there was more frequent contact with humans. Variation in diversity was observed in the free-ranging, terrestrial population, Lemur catta, who I observed in the field as approaching gated areas and trails that people often occupied. In human forehead samples, taxa associated with the phylum Bacteroides were observed. Both lemur fecal samples and human skin samples harbored Bacteroides, demonstrating the presence of non-endemic microbes in lemur guts. In humans, this revealed that animal caretakers can exhibit altered microbial diversity due to contact intensity with lemurs since taxa from the Bacteroides phylum were observed in high relative abundance on the human skin microbiome of the animal husbandry interns only, which is contrary to past studies. Understanding the mechanisms of microbiome transmissions among humans and non-human primates is especially important for the conservation of captive non-human primates and the health of the humans managing captive populations. Transmission of microbes among humans and non-human primates can provide key information on how to best serve these captive populations and manage facilities to ensure the best outcomes for rehabilitation and conservation of species.

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