Rethinking Human-Nonhuman Primate Contact and Pathogenic Disease Spillover

Seasonal Patterns of Mpox Index Cases, Africa, 1970-2021

Across 133 confirmed mpox zoonotic index cases reported during 1970-2021 in Africa, cases occurred year-round near the equator, where climate is consistent. However, in tropical regions of the northern hemisphere under a dry/wet season cycle, cases occurred seasonally. Our findings further support the seasonality of mpox zoonotic transmission risk.

Human behaviors driving disease emergence

Interactions between humans, animals, and the environment facilitate zoonotic spillover-the transmission of pathogens from animals to humans. Narratives that cast modern humans as exogenous and disruptive forces that encroach upon "natural" disease systems limit our understanding of human drivers of disease. This review leverages theory from evolutionary anthropology that situates humans as functional components of disease ecologies, to argue that human adaptive strategies to resource acquisition shape predictable patterns of high-risk human-animal interactions, (2) humans construct ecological processes that facilitate spillover, and (3) contemporary patterns of epidemiological risk are emergent properties of interactions between human foraging ecology and niche construction. In turn, disease ecology serves as an important vehicle to link what some cast as opposing bodies of theory in human ecology. Disease control measures should consider human drivers of disease as rational, adaptive, and dynamic and capitalize on our capacity to influence ecological processes to mitigate risk.

Strongyloides in non-human primates: significance for public health control

Primates are an important source of infectious disease in humans. Strongyloidiasis affects an estimated 600 million people worldwide, with a global distribution and hotspots of infection in tropical and subtropical regions. Recently added to the list of neglected tropical diseases, global attention has been demanded in the drive for its control. Through a literature review of Strongyloides in humans and non-human primates (NHP), we analysed the most common identification methods and gaps in knowledge about this nematode genus. The rise of molecular-based methods for Strongyloides detection is evident in both humans and NHP and provides an opportunity to analyse all data available from primates. Dogs were also included as an important host species of Strongyloides and a potential bridge host between humans and NHP. This review highlights the lack of molecular data across all hosts-humans, NHP and dogs-with the latter highly underrepresented in the database. Despite the cosmopolitan nature of Strongyloides, there are still large gaps in our knowledge for certain species when considering transmission and pathogenicity. We suggest that a unified approach to Strongyloides detection be taken, with an optimized, repeatable molecular-based method to improve our understanding of this parasitic infection. This article is part of the Theo Murphy meeting issue 'Strongyloides: omics to worm-free populations'.

Contesting the Reservoir: Guarani-Mbya Criticisms of Zoonosis, Race, and Dirt in the Jaraguá Indigenous Land, Brazil

In Brazil, epidemiological understandings of zoonosis have historically articulated with race and class hierarchies, placing so-called non-modern bodies at the core of etiological theories and sanitary interventions. I describe how the Guarani-Mbya people living in the Jaraguá Indigenous Land in the city of São Paulo question the racialized narratives that human-rat contact is a major driver of infections such as leptospirosis. By analyzing Indigenous concepts of body, disease, and dirt, I suggest that the Guarani-Mbya disease ontology reflects a criticism of urbanization, in that it is considered to have pathogenic effects on the lives of Indigenous peoples and rats.

Propagating Visions of a Forest Reservoir: A Supposed Zoonotic Outbreak in the Brong-Ahafo Region of Ghana

When examined closely, the backgrounds of some of the most widely cited origin stories for zoonotic disease outbreaks have been found to be irreconcilable with empirical data. Stated simply, these explanatory landscapes do not appear to have existed. Here, I present a detailed case study of one such fictional landscape, that of a monkey-filled forest which was identified as the source of a suspected zoonotic outbreak in the Brong-Ahafo Region of Ghana in 2010. Taking my approach from cultural epidemiology, I elucidate the mechanisms by which this fictional landscape was constructed and transmitted among the professionals involved in the response.

Introduction: Disease Reservoirs: From Colonial Medicine to One Health

The introduction of the special issue "Disease Reservoirs: Anthropological and Historical Approaches" sets out the origins and trajectories of disease reservoir frameworks. First, it charts the emergence and elaborations of the reservoirs concept within and across early 20th-century colonial contexts, emphasising its configuration within imperial projects that sought to identify, map and control spaces of contagion among humans, animals, and pathogens. Following this, it traces the position the reservoir framework assumed within post-colonial practices and imaginaries of global health, with particular reference to the emerging infectious disease paradigm. The introduction shows that, in contemporary usages, while the concept continues to frame animals, humans and their bodies as containers of previously identified pathogens, it also emphasises the imperative of anticipating as-of-yet unknown diseases, harboured in the bodies of certain animals, through networks and techniques of surveillance. Consequently, the introduction argues that the notion of disease reservoirs remains intimately intertwined with concerns over the classification, organization, and management of peoples, pathogens, animals, and space. Finally, the introduction outlines the seven papers that form this special issue, stressing how they dialogue, complement, and challenge previous historical and anthropological approaches to disease reservoirs, with an eye to opening up new avenues for cross-disciplinary exploration.

It Was Not the Perfect Storm: The Social History of the HIV-2 Virus in Guinea-Bissau

The perfect storm model that was elaborated for the HIV-1M pandemic has also been used to explain the emergence of HIV-2, a second human immunodeficiency virus-acquired immunodeficiency syndrome (HIV-AIDS) that became an epidemic in Guinea-Bissau, West Africa. The use of this model creates epidemiological generalizations, ecological oversimplifications and historical misunderstandings as its assumptions-an urban center with explosive population growth, a high level of commercial sex and a surge in STDs, a network of mechanical transport and country-wide, en masse mobile campaigns-are absent from the historical record. This model fails to explain how the HIV-2 epidemic actually came about. This is the first study to conduct an exhaustive examination of sociohistorical contextual developments and align them with environmental, virological and epidemiological data. The interdisciplinary dialogue indicates that the emergence of the HIV-2 epidemic piggybacked on local sociopolitical transformations. The war's indirect effects on ecological relations, mobility and sociability were acute in rural areas and are a key to the HIV-2 epidemic. This setting had the natural host of the virus, the population numbers, the mobility trends and the use of technology on a scale needed to foster viral adaptation and amplification. The present analysis suggests new reflections on the processes of zoonotic spillovers and disease emergence.

Living Safely With Bats: Lessons in Developing and Sharing a Global One Health Educational Resource

As part of a public health behavior change and communication strategy related to the identification of a novel ebolavirus in bats in Sierra Leone in 2016, a consortium of experts launched an effort to create a widely accessible resource for community awareness and education on reducing disease risk. The resulting picture book, Living Safely With Bats, includes technical content developed by a consortium of experts in public health, animal health, conservation, bats, and disease ecology from 30 countries. The book has now been adapted, translated, and used in more than 20 countries in Africa and Asia. We review the processes used to integrate feedback from local stakeholders and multidisciplinary experts. We also provide recommendations for One Health and other practitioners who choose to pursue the development and evaluation of this or similar zoonotic disease risk mitigation tools.

Postscript: A pandemic read on African health and environmental histories

This postscript reflects on this special issue's contributions for readers preoccupied with the COVID-19 pandemic. First, these articles on African environment and health underscore that past process of and interventions into land use and human health have cumulative effects on disease emergence and re-emergence. Relatedly, although multiple epidemics have affected the African continent and other parts of the world over the past century, global health institutions and actors have sidelined or forgotten these epidemics. These analyses draw our attention to the historical production and mobilization of specific concepts which frame what questions are asked, how they are answered, and the material solutions provided or withheld. And finally, these pieces highlight the ethical stakes of agricultural, conservation, and health interventions, reminding us that the African continent's histories are fraught with inequities from colonial and postcolonial extractive relations and racist assumptions that have undermined livelihoods, food security and health. As African states, institutions, and global health critics politick for vaccine equity and deplore the inequitable access to COVID-19 vaccines in African countries compared to the rest of the world, these articles remind us that these long-standing inequities should catalyze fundamental change.

The role of great ape behavioral ecology in One Health: Implications for captive welfare and re-habilitation success

Behavior is the interface through which animals interact with their environments, and therefore has potentially cascading impacts on the health of individuals, populations, their habitats, and the humans that share them. Evolution has shaped the interaction between species and their environments. Thus, alterations to the species-typical "wild-type" behavioral repertoire (and the ability of the individual to adapt flexibly which elements of the repertoire it employs) may disrupt the relationship between the organism and its environment, creating cascading One Health effects. A good example is rehabilitant orangutans where, for example, seemingly minor differences from wild conspecifics in the time spent traveling on the ground rather than in the forest canopy can affect an individual's musculoskeletal and nutritional health, as well as social integration. It can also increase two-way transmission of infectious diseases and/or pathogens with local human populations, or potentially with neighboring wild populations if there are no geographical barriers and rehabilitants travel far enough to leave their release area. Primates are well known ecosystem engineers, reshaping plant communities and maintaining biodiversity through seed dispersal, consuming plants, and creating canopy gaps and trails. From the habitat perspective, a rehabilitant orangutan which does not behave like a wild orangutan is unlikely to fulfill these same ecosystem services. Despite the importance of the diversity of an ape's behavioral repertoire, how it compares to that of wild conspecifics and how it alters in response to habitat variation, behavior is an often under-appreciated aspect of One Health. In this review, focusing on orangutans as an example of the kinds of problems faced by all captive great apes, we examine the ways in which understanding and facilitating the expression of wild-type behavior can improve their health, their ability to thrive, and the robustness of local One Health systems.

Sparse Evidence for Giardia intestinalis, Cryptosporidium spp. and Microsporidia Infections in Humans, Domesticated Animals and Wild Nonhuman Primates Sharing a Farm-Forest Mosaic Landscape in Western Uganda

Zoonotic pathogen transmission is considered a leading threat to the survival of non-human primates and public health in shared landscapes. Giardia spp., Cryptosporidium spp. and Microsporidia are unicellular parasites spread by the fecal-oral route by environmentally resistant stages and can infect humans, livestock, and wildlife including non-human primates. Using immunoassay diagnostic kits and amplification/sequencing of the region of the triosephosphate isomerase, small ribosomal subunit rRNA and the internal transcribed spacer genes, we investigated Giardia, Cryptosporidium, and microsporidia infections, respectively, among humans, domesticated animals (livestock, poultry, and dogs), and wild nonhuman primates (eastern chimpanzees and black and white colobus monkeys) in Bulindi, Uganda, an area of remarkably high human-animal contact and spatial overlap. We analyzed 137 fecal samples and revealed the presence of G. intestinalis assemblage B in two human isolates, G. intestinalis assemblage E in one cow isolate, and Encephalitozoon cuniculi genotype II in two humans and one goat isolate. None of the chimpanzee and colobus monkey samples were positive for any of the screened parasites. Regular distribution of antiparasitic treatment in both humans and domestic animals in Bulindi could have reduced the occurrence of the screened parasites and decreased potential circulation of these pathogens among host species.

Implications of Zoonoses From Hunting and Use of Wildlife in North American Arctic and Boreal Biomes: Pandemic Potential, Monitoring, and Mitigation

The COVID-19 pandemic has re-focused attention on mechanisms that lead to zoonotic disease spillover and spread. Commercial wildlife trade, and associated markets, are recognized mechanisms for zoonotic disease emergence, resulting in a growing global conversation around reducing human disease risks from spillover associated with hunting, trade, and consumption of wild animals. These discussions are especially relevant to people who rely on harvesting wildlife to meet nutritional, and cultural needs, including those in Arctic and boreal regions. Global policies around wildlife use and trade can impact food sovereignty and security, especially of Indigenous Peoples. We reviewed known zoonotic pathogens and current risks of transmission from wildlife (including fish) to humans in North American Arctic and boreal biomes, and evaluated the epidemic and pandemic potential of these zoonoses. We discuss future concerns, and consider monitoring and mitigation measures in these changing socio-ecological systems. While multiple zoonotic pathogens circulate in these systems, risks to humans are mostly limited to individual illness or local community outbreaks. These regions are relatively remote, subject to very cold temperatures, have relatively low wildlife, domestic animal, and pathogen diversity, and in many cases low density, including of humans. Hence, favorable conditions for emergence of novel diseases or major amplification of a spillover event are currently not present. The greatest risk to northern communities from pathogens of pandemic potential is via introduction with humans visiting from other areas. However, Arctic and boreal ecosystems are undergoing rapid changes through climate warming, habitat encroachment, and development; all of which can change host and pathogen relationships, thereby affecting the probability of the emergence of new (and re-emergence of old) zoonoses. Indigenous leadership and engagement in disease monitoring, prevention and response, is vital from the outset, and would increase the success of such efforts, as well as ensure the protection of Indigenous rights as outlined in the United Nations Declaration on the Rights of Indigenous Peoples. Partnering with northern communities and including Indigenous Knowledge Systems would improve the timeliness, and likelihood, of detecting emerging zoonotic risks, and contextualize risk assessments to the unique human-wildlife relationships present in northern biomes.

Social representations of animal diseases: anthropological approaches to pathogens crossing species barriers

Debates about emerging infectious diseases often oppose natural conceptions of zoonotic reservoirs with cultural practices bringing humans into contact with animals. This article compares the representations of cross-species pathogens at ontological levels below the opposition between nature and culture. It describes the perceptions of distinctions between interiority and physicality, between wild and domestic, and between sick and dead in three different contexts where human societies manage animal diseases: Australia, Laos and Mongolia. Our article also argues that zoonotic pathogens are one of the entities mobilized by local knowledge to attenuate troubles in ordinary relations with animals, and shows that the conservation of cultural heritage is a tool of mitigation for infectious diseases emerging in animal reservoirs.

Potential zoonotic pathogens hosted by endangered bonobos

Few publications, often limited to one specific pathogen, have studied bonobos (Pan paniscus), our closest living relatives, as possible reservoirs of certain human infectious agents. Here, 91 stool samples from semicaptive bonobos and bonobos reintroduced in the wild, in the Democratic Republic of the Congo, were screened for different infectious agents: viruses, bacteria and parasites. We showed the presence of potentially zoonotic viral, bacterial or parasitic agents in stool samples, sometimes coinfecting the same individuals. A high prevalence of Human mastadenoviruses (HAdV-C, HAdV-B, HAdV-E) was observed. Encephalomyocarditis viruses were identified in semicaptive bonobos, although identified genotypes were different from those identified in the previous fatal myocarditis epidemic at the same site in 2009. Non-pallidum Treponema spp. including symbiotic T. succinifaciens, T. berlinense and several potential new species with unknown pathogenicity were identified. We detected DNA of non-tuberculosis Mycobacterium spp., Acinetobacter spp., Salmonella spp. as well as pathogenic Leptospira interrogans. Zoonotic parasites such as Taenia solium and Strongyloides stercoralis were predominantly present in wild bonobos, while Giardia lamblia was found only in bonobos in contact with humans, suggesting a possible exchange. One third of bonobos carried Oesophagostomum spp., particularly zoonotic O. stephanostomum and O. bifurcum-like species, as well as other uncharacterized Nematoda. Trypanosoma theileri has been identified in semicaptive bonobos. Pathogens typically known to be transmitted sexually were not identified. We present here the results of a reasonably-sized screening study detecting DNA/RNA sequence evidence of potentially pathogenic viruses and microorganisms in bonobo based on a noninvasive sampling method (feces) and focused PCR diagnostics.

An Ethnographic Approach to Characterizing Potential Pathways of Zoonotic Disease Transmission from Wild Meat in Guyana

The hunting, butchery, and consumption of wild meat is an important interface for zoonotic disease transmission. Despite this, few researchers have used ethnography to understand the sociocultural factors that may increase zoonotic disease transmission from hunting, particularly in Amazonia. Here, we use ethnographic methods consisting of structured, semi-structured and unstructured interviews, and participant observation to address questions pertaining to wild meat consumption, pathways of zoonotic disease transmission, food security, and the cultural identity of indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. Our data revealed that the majority of Waiwai eat wild meat two to three times/week and 60% of respondents reported butchery-related injuries. However, semi-structured and unstructured interviews, and participant observation data indicate that the Waiwai do not perceive most cuts from butchery as injuries, despite being a potential route of pathogen exposure. Additionally, participant observation revealed that hunting is integral to Waiwai identity and the Waiwai exhibit a cultural aversion to domestic meats. These findings provide valuable insights into the interplay of hunting and wild meat consumption and disease in Amazonia and demonstrate how an ethnographic approach provides the contextual data necessary for identifying potential pathways of zoonotic transmission from wild meat.

Infectious Disease Risk Across the Growing Human-Non Human Primate Interface: A Review of the Evidence

Most of the human pandemics reported to date can be classified as zoonoses. Among these, there is a long history of infectious diseases that have spread from non-human primates (NHP) to humans. For millennia, indigenous groups that depend on wildlife for their survival were exposed to the risk of NHP pathogens' transmission through animal hunting and wild meat consumption. Usually, exposure is of no consequence or is limited to mild infections. In rare situations, it can be more severe or even become a real public health concern. Since the emergence of acquired immune deficiency syndrome (AIDS), nobody can ignore that an emerging infectious diseases (EID) might spread from NHP into the human population. In large parts of Central Africa and Asia, wildlife remains the primary source of meat and income for millions of people living in rural areas. However, in the past few decades the risk of exposure to an NHP pathogen has taken on a new dimension. Unprecedented breaking down of natural barriers between NHP and humans has increased exposure to health risks for a much larger population, including people living in urban areas. There are several reasons for this: (i) due to road development and massive destruction of ecosystems for agricultural needs, wildlife and humans come into contact more frequently; (ii) due to ecological awareness, many long distance travelers are in search of wildlife discovery, with a particular fascination for African great apes; (iii) due to the attraction for ancient temples and mystical practices, others travelers visit Asian places colonized by NHP. In each case, there is a risk of pathogen transmission through a bite or another route of infection. Beside the individual risk of contracting a pathogen, there is also the possibility of starting a new pandemic. This article reviews the known cases of NHP pathogens' transmission to humans whether they are hunters, travelers, ecotourists, veterinarians, or scientists working on NHP. Although pathogen transmission is supposed to be a rare outcome, Rabies virus, Herpes B virus, Monkeypox virus, Ebola virus, or Yellow fever virus infections are of greater concern and require quick countermeasures from public health professionals.

Multidisciplinarity in Microbiome Research: A Challenge and Opportunity to Rethink Causation, Variability, and Scale

This essay, written by a biologist, a microbial ecologist, a biological anthropologist, and an anthropologist-historian, examines tensions and translations in microbiome research on animals in the laboratory and field. The authors trace how research questions and findings in the laboratory are extrapolated into the field and vice versa, and the shifting evidentiary standards that these research settings require. Showing how complexities of microbiomes challenge traditional standards of causation, the authors contend that these challenges require new approaches to inferences used in ecology, anthropology, and history. As social scientists incorporate investigations of microbial life into their human studies, microbiome researchers venture into field settings to develop mechanistic understandings about the functions of complex microbial communities. These efforts generate new possibilities for cross-fertilizations and inference frameworks to interpret microbiome findings. Microbiome research should integrate multiple scales, levels of variability, and other disciplinary approaches to tackle questions spanning conditions from the laboratory to the field.

Should monkeys wash their hands and feet: A pilot-study on sources of zoonotic parasite exposure

Human exposure to zoonotic parasites via contaminated soil is a much studied area. Less research has been performed on exposure via contact with animals and surfaces such as picnic tables with which infected animals might be in contact. On St. Kitts, wild African green monkeys (AGM; Chlorocebus aethiops sabaeus), which are known to have zoonotic parasites, roam freely in areas with outdoor dining facilities and are used in the tourist industry. In this study, the hands and feet of eight AGM and picnic tables where AGM were known to walk on were examined for parasitic organisms. Six of the AGM had parasitic organisms on their hands and/or feet. Trichuris spp. eggs, hookworm larvae and eggs and pinworm eggs were recovered from the tables. The results of this pilot study highlight other potential means of transfer of zoonotic parasites and suggest that surfaces without obvious fecal material can be contaminated with zoonotic parasites.

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Trichuris trichiura and hookworms were found on the hands and feet of monkeys

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Parasitic organisms were found on picnic tables frequented by monkeys and cats

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Vervets and other animals could transfer parasitic stages via walking on surfaces

Using physical contact heterogeneity and frequency to characterize dynamics of human exposure to nonhuman primate bodily fluids in central Africa

Emerging infectious diseases of zoonotic origin constitute a recurrent threat to global health. Nonhuman primates (NHPs) occupy an important place in zoonotic spillovers (pathogenic transmissions from animals to humans), serving as reservoirs or amplifiers of multiple neglected tropical diseases, including viral hemorrhagic fevers and arboviruses, parasites and bacteria, as well as retroviruses (simian foamy virus, PTLV) that are pathogenic in human beings. Hunting and butchering studies in Africa characterize at-risk human social groups, but overlook critical factors of contact heterogeneity and frequency, NHP species differences, and meat processing practices. In southeastern Cameroon, a region with a history of zoonotic emergence and high risk of future spillovers, we conducted a novel mixed-method field study of human physical exposure to multiple NHP species, incorporating participant-based and ecological methodologies, and qualitative interviews (n = 25). We find frequent physical contact across adult human populations, greater physical contact with monkeys than apes, especially for meat handling practices, and positive correlation of human exposure with NHP species abundance and proximity to human settlement. These fine-grained results encourage reconsideration of the likely dynamics of human-NHP contact in past and future NTD emergence events. Multidisciplinary social science and ecological approaches should be mobilized to generate more effective human and animal surveillance and risk communications around neglected tropical diseases. At a moment when the WHO has included "Disease X", a presumably zoonotic pathogen with pandemic potential, on its list of blueprint priority diseases as, new field-based tools for investigating zoonotic disease emergence, both known and unknown, are of critical importance.

A systematic review of evidence that enteroviruses may be zoonotic

Enteroviruses infect millions of humans annually worldwide, primarily infants and children. With a high mutation rate and frequent recombination, enteroviruses are noted to evolve and change over time. Given the evidence that human enteroviruses are commonly found in other mammalian species and that some human and animal enteroviruses are genetically similar, it is possible that enzootic enteroviruses may also be infecting human populations. We conducted a systematic review of the English and Chinese literature published between 2007 and 2017 to examine evidence that enteroviruses may be zoonotic. Of the 2704 articles screened for inclusion, 16 articles were included in the final review. The review of these articles yielded considerable molecular evidence of zooanthroponosis transmission, particularly among non-human primates. While there were more limited instances of anthropozoonosis transmission, the available data support the biological plausibility of cross-species transmission and the need to conduct periodic surveillance at the human–animal interface.