Risk assessment: a model for predicting cross-species transmission of simian foamy virus from macaques (M. fascicularis) to humans at a monkey temple in Bali, Indonesia

Zoonotic pathogens in wild Asian primates: a systematic review highlighting research gaps

Introduction

Ongoing global changes, including natural land conversion for agriculture and urbanization, modify the dynamics of human-primate contacts, resulting in increased zoonotic risks. Although Asia shelters high primate diversity and experiences rapid expansion of human-primate contact zones, there remains little documentation regarding zoonotic surveillance in the primates of this region.

Methods

Using the PRISMA guidelines, we conducted a systematic review to compile an inventory of zoonotic pathogens detected in wild Asian primates, while highlighting the coverage of primate species, countries, and pathogen groups surveyed, as well as the diagnostic methods used across the studies. Moreover, we compared the species richness of pathogens harbored by primates across diverse types of habitats classified according to their degree of anthropization (i.e., urban vs. rural vs. forest habitats).

Results and discussion

Searches of Scopus, PubMed, and the Global Mammal Parasite Database yielded 152 articles on 39 primate species. We inventoried 183 pathogens, including 63 helminthic gastrointestinal parasites, two blood-borne parasites, 42 protozoa, 45 viruses, 30 bacteria, and one fungus. Considering each study as a sample, species accumulation curves revealed no significant differences in specific richness between habitat types for any of the pathogen groups analyzed. This is likely due to the insufficient sampling effort (i.e., a limited number of studies), which prevents drawing conclusive findings. This systematic review identified several publication biases, particularly the uneven representation of host species and pathogen groups studied, as well as a lack of use of generic diagnostic methods. Addressing these gaps necessitates a multidisciplinary strategy framed in a One Health approach, which may facilitate a broader inventory of pathogens and ultimately limit the risk of cross-species transmission at the human-primate interface. Strengthening the zoonotic surveillance in primates of this region could be realized notably through the application of more comprehensive diagnostic techniques such as broad-spectrum analyses without a priori selection.

Rabies exposure in travellers to Asia, the Middle East, Africa, South and Central America-a German Airport study

BACKGROUND

Rabies causes thousands of deaths worldwide and trips to rabies endemic countries are popular. Travellers are often uncertain whether pre-exposure prophylaxis (PrEP) is advisable since they find it difficult to estimate the exposure risk during travel and the availability of post-exposure prophylaxis in endemic regions. The aim of this study was to determine the potential rabies exposures in travellers and to assess their knowledge on rabies. Secondly, we explored the access to appropriate post-exposure medical care in respective countries.

METHODS

We conducted a cross-sectional study at Frankfurt Airport. Returning adult travellers arriving from Asia, the Middle East, Africa, South and Central America were invited to participate in this questionnaire-based study while waiting in the baggage claim area.

RESULTS

Over a one-month recruitment phase in March 2019, we enrolled 3066 travellers; 2929 were included in the analysis. The gender ratio was balanced; the median age was 42 years (range 18-83 years). Participants arrived from Asia (46%), Africa (29%), Central/South America (13%), the Middle East (8%) and the Caribbean (8%). Forty-five per cent sought pretravel advice and 22% received ≥2 injections of rabies PrEP. Travellers with pretravel advice from tropical medicine specialists reached significantly higher knowledge scores than others. We found that potential rabies exposure occurred in 2.0% (57/2915) of travellers with 31% (13/42) of the contacts being unprovoked; 19% (8/42) of the exposed sought medical care and 3/8 were adequately treated before returning to Germany. Risk factors for animal exposure were: male sex, young age, trips to Asia and a long stay abroad (>4 weeks).

CONCLUSIONS

A total of 2% of returning travellers (n = 2915) experienced a potential rabies exposure during their journey. A majority of the exposed individuals did not seek medical care; those seeking medical care were often treated inadequately. Rabies information must be emphasised during pretravel counselling and PrEP should be offered generously, especially to travellers with high exposure risks.

Ethics of Primate Fieldwork: Toward an Ethically Engaged Primatology

Field primatologists have ethical responsibilities that extend beyond study subjects to the local human communities living near primate populations and their surrounding ecosystems. In this review, we explore the history of ethical discussions within anthropological primatology and examine the best practices for an ethically engaged primatology that should be followed and role-modeled by primatologists. An increasing number of primates are showing reduced population sizes and are in imminent danger of extinction; thus, we need to carefully consider the ethics of intervening to ensure the survival of remaining populations, the impact of anthropogenic factors (e.g., climate change), and whether long-term field research results in conservation outcomes that consider local human communities. Because best practices change over time as theoretical frameworks and methodological tools advance and scientific goals change, field primatologists must continually reflect on what constitutes ethical practice and consider how research influences the overlapping dimensions of fieldwork: primates, people, and ecosystems.

Primates on display: Potential disease consequences beyond bushmeat

Human interactions with nonhuman primates vary tremendously, from daily cultural engagements and food commodities, to pet ownership and tourist encounters. These interactions provide opportunities for the exchange of pathogenic organisms (both zoonoses and anthroponoses). As exposures are not limited to areas where bushmeat usage continues to be a major problem, we must work to understand better our motivations for engaging in activities like owning primates as pets and having direct physical contact with wild primates within the context of nature-based tourism. These topics, and the theoretical potential for pathogen transmission, are reviewed in the present manuscript. This is followed by a case study utilizing 3845 survey responses collected from four international locations known for primate-based tourism, with results indicating that while a majority of people understand that they can give/get diseases to/from wild primates, a surprising percentage would still touch or feed these animals if given the opportunity. Many people still choose to touch and/or own primates, as their drive to bond with animals outweighs some basic health behaviors. Desires to tame, control, or otherwise establish emotional connections with other species, combined with the central role of touch for exploring our environment, necessitate the development of better communication and educational campaigns to minimize risks of emerging infectious diseases.

Understanding Primate Herpesviruses

Viruses related to the herpes simplex viruses of humans are present in all nonhuman primate (NHP) species tested and cross species transmission has been documented. The herpesvirus present in macaques, Herpes B virus (BV) rarely causes disease in its natural macaque host. However, when transmitted to a nonnative host, BV has occasionally caused severe and even fatal disease if not treated immediately. Here we present a comprehensive review of the taxonomy, molecular biology, physiology, epidemiology, diagnosis and treatment of BV. We also summarizes what is known about related herpesviruses of other NHP species and the zoonotic potential of these viruses.

Disease and Human/Animal Interactions

Understanding pathogen exchange among human, wildlife, and livestock populations, and the varying ecological and cultural contexts in which this exchange takes place, is a major challenge. The present review contextualizes the risk factors that result from human interactions with livestock, companion animals, animal exhibits, wildlife through nature-based tourism, and wildlife through consumption. Given their phylogenetic relatedness to humans, primates are emphasized in this discussion; primates serve as reservoirs for several human pathogens, and some human pathogens can decimate wild primate populations. Anthropologists must play a central role in understanding cultural variation in attitudes toward other species as well as perceived risks when interacting with animals. I argue that the remediation of emerging infectious diseases will be accomplished primarily through human behavioral changes rather than through efforts in pathogen discovery. Given the history of human interactions with wildlife, candid discussions on zoonotic diseases will be increasingly important for our combined survival.

Macacine Herpesvirus 1 in Long-Tailed Macaques, Malaysia, 2009-2011

Virus shedding by 39% of wild-caught macaques creates potential occupational risk for humans.

Macacine herpesvirus 1 (MaHV1; B virus) naturally infects macaques (Macaca spp.) and can cause fatal encephalitis in humans. In Peninsular Malaysia, wild macaques are abundant, and translocation is used to mitigate human–macaque conflict. Most adult macaques are infected with MaHV1, although the risk for transmission to persons who handle them during capture and translocation is unknown. We investigated MaHV1 shedding among 392 long-tailed macaques (M. fascicularis) after capture and translocation by the Department of Wildlife and National Parks in Peninsular Malaysia, during 2009–2011. For detection of MaHV1 DNA, PCR was performed on urogenital and oropharyngeal swab samples. Overall, 39% of macaques were shedding MaHV1 DNA; rates of DNA detection did not differ between sample types. This study demonstrates that MaHV1 was shed by a substantial proportion of macaques after capture and transport and suggests that persons handling macaques under these circumstances might be at risk for exposure to MaHV1.

Rabies Postexposure Prophylaxis for Travelers Injured by Nonhuman Primates, Marseille, France, 2001-2014

Most exposures of residents of Marseille to nonhuman primates occurred among unvaccinated adult travelers to Southeast Asia within the first 10 days of their arrival at 2 major tourist locations in Thailand and 1 in Indonesia. A small proportion of travelers received rabies immunoglobulin in the country of exposure.

Conservation Medicine: A Solution-Based Approach for Saving Nonhuman Primates

Challenges that threaten the long-term survival of nonhuman primates (NHP) include habitat fragmentation, hunting, and increasingly, infectious diseases. In addition to direct mortality from noninfectious diseases (e.g., hunting) and infectious diseases (e.g., Ebola), human-driven alterations of environments that support NHP often contribute to a decline in population viability. This decline is frequently the result of physiological stress, poor reproduction, decreased immunity, and exposure to novel pathogens. To better understand the diseases that threaten NHP populations, a conservation medicine approach—the application of medicine to augment the conservation of wildlife and ecosystems—is imperative so that we may provide management solutions to help ensure the long-term survival of NHP. Additionally, it is crucial that we gain a better understanding of pathogens at the interface of nonhuman and human primates since the zoonotic potential may create conservation challenges, or alternatively may provide the impetus for conservation actions to be practiced (e.g., minimize bushmeat trade).

Replication-Competent Foamy Virus Vaccine Vectors as Novel Epitope Scaffolds for Immunotherapy

The use of whole viruses as antigen scaffolds is a recent development in vaccination that improves immunogenicity without the need for additional adjuvants. Previous studies highlighted the potential of foamy viruses (FVs) in prophylactic vaccination and gene therapy. Replication-competent FVs can trigger immune signaling and integrate into the host genome, resulting in persistent antigen expression and a robust immune response. Here, we explored feline foamy virus (FFV) proteins as scaffolds for therapeutic B and T cell epitope delivery in vitro. Infection- and cancer-related B and T cell epitopes were grafted into FFV Gag, Env, or Bet by residue replacement, either at sites of high local sequence homology between the epitope and the host protein or in regions known to tolerate sequence alterations. Modified proviruses were evaluated in vitro for protein steady state levels, particle release, and virus titer in permissive cells. Modification of Gag and Env was mostly detrimental to their function. As anticipated, modification of Bet had no impact on virion release and affected virus titers of only some recombinants. Further evaluation of Bet as an epitope carrier was performed using T cell epitopes from the model antigen chicken ovalbumin (OVA), human tyrosinase-related protein 2 (TRP-2), and oncoprotein E7 of human papillomavirus type 16 (HPV16E7). Transfection of murine cells with constructs encoding Bet-epitope chimeric proteins led to efficient MHC-I-restricted epitope presentation as confirmed by interferon-gamma enzyme-linked immunospot assays using epitope-specific cytotoxic T lymphocyte (CTL) lines. FFV infection-mediated transduction of cells with epitope-carrying Bet also induced T-cell responses, albeit with reduced efficacy, in a process independent from the presence of free peptides. We show that primate FV Bet is also a promising T cell epitope carrier for clinical translation. The data demonstrate the utility of replication-competent and -attenuated FVs as antigen carriers in immunotherapy.

Optimization of a Novel Non-invasive Oral Sampling Technique for Zoonotic Pathogen Surveillance in Nonhuman Primates

Free-ranging nonhuman primates are frequent sources of zoonotic pathogens due to their physiologic similarity and in many tropical regions, close contact with humans. Many high-risk disease transmission interfaces have not been monitored for zoonotic pathogens due to difficulties inherent to invasive sampling of free-ranging wildlife. Non-invasive surveillance of nonhuman primates for pathogens with high potential for spillover into humans is therefore critical for understanding disease ecology of existing zoonotic pathogen burdens and identifying communities where zoonotic diseases are likely to emerge in the future. We developed a non-invasive oral sampling technique using ropes distributed to nonhuman primates to target viruses shed in the oral cavity, which through bite wounds and discarded food, could be transmitted to people. Optimization was performed by testing paired rope and oral swabs from laboratory colony rhesus macaques for rhesus cytomegalovirus (RhCMV) and simian foamy virus (SFV) and implementing the technique with free-ranging terrestrial and arboreal nonhuman primate species in Uganda and Nepal. Both ubiquitous DNA and RNA viruses, RhCMV and SFV, were detected in oral samples collected from ropes distributed to laboratory colony macaques and SFV was detected in free-ranging macaques and olive baboons. Our study describes a technique that can be used for disease surveillance in free-ranging nonhuman primates and, potentially, other wildlife species when invasive sampling techniques may not be feasible.

Wild nonhuman primates are frequent sources of pathogens that could be transmitted to humans because they are closely genetically related and have intimate contact with humans in many parts of the world. Sampling primates to screen for zoonotic pathogens is logistically challenging because standard invasive sampling techniques, such as the collection of a blood sample or an oral swab, requires field anesthesia. This research describes a non-invasive oral sampling technique that involves distributing a rope for primates to chew on that can be retrieved and screened for pathogens. Oral samples were successfully collected from multiple wild primate species in remote field settings and viruses were detected in those samples. This non-invasive sampling method has the potential for future applications in disease studies examining primates as sources of diseases that could affect humans in remote tropical settings.

Zoonotic simian foamy virus in Bangladesh reflects diverse patterns of transmission and co-infection

Simian foamy viruses (SFVs) are ubiquitous in non-human primates (NHPs). As in all retroviruses, reverse transcription of SFV leads to recombination and mutation. Because more humans have been shown to be infected with SFV than with any other simian borne virus, SFV is a potentially powerful model for studying the virology and epidemiology of viruses at the human/NHP interface. In Asia, SFV is likely transmitted to humans through macaque bites and scratches that occur in the context of everyday life. We analyzed multiple proviral sequences from the SFV gag gene from both humans and macaques in order to characterize retroviral transmission at the human/NHP interface in Bangladesh. Here we report evidence that humans can be concurrently infected with multiple SFV strains, with some individuals infected by both an autochthonous SFV strain as well as a strain similar to SFV found in macaques from another geographic area. These data, combined with previous results, suggest that both human-facilitated movement of macaques leading to the introduction of non-resident strains of SFV and retroviral recombination in macaques contribute to SFV diversity among humans in Bangladesh.

Frequency of different human mollicutes species in the mucosa of the oropharynx, conjunctiva, and genitalia of free-ranging and captive capuchin monkeys (Cebus spp.)

This study is the first to evaluate the occurrence of several Mollicutes species in Brazilian capuchin monkeys (Cebus spp.). Mollicutes were detected by culture and polymerase chain reaction (PCR) in samples of the oropharyngeal, conjuctiva, and genital mucosae of 58 monkeys. In the oropharynx, Mollicutes in general (generic PCR to the Class), and those of the genus Ureaplasma (genus PCR), were detected in 72.4% and 43.0% of the samples, respectively. The identified species in this site included: Mycoplasma arginini (43.1%), M. salivarium (41.4%), and M. pneumoniae (19.0%). Both Ureaplasma and Mycoplasma are genera of the order Mycoplasmatales. In the preputial/vaginal mucosa, PCR detected Mollicutes in general in 27.58% of the samples, the genus Ureaplasma in 32.7%, the species M. arginini in 8.6%, and Acholeplasma laidlawii of the order Acholeplasmatales in 1.7% In the conjunctiva, Mollicutes in general were detected in 29.3% of the samples, with 1.7% being identified as A. laidlawii. Culturing was difficult due to contamination, but two isolates were successfully obtained. The Mollicutes species of this study provided new insights into these bacteria in Brazilian Cebus. Studies are lacking of the actual risk of Mollicutes infection or the frequency at which primates serve as permanent or temporary reservoirs for Mollicutes. In the present study, the samples were collected from monkeys without clinical signs of infection. The mere presence of Mollicutes, particularly those also found in humans, nevertheless signals a need for studies to evaluate the impact of these microorganisms on the health of non-human primates (NHPs) and the possibility of cross-species transmission between NHPs and humans.

HTLV-3/4 and simian foamy retroviruses in humans: discovery, epidemiology, cross-species transmission and molecular virology

Non-human primates are considered to be likely sources of viruses that can infect humans and thus pose a significant threat to human population. This is well illustrated by some retroviruses, as the simian immunodeficiency viruses and the simian T lymphotropic viruses, which have the ability to cross-species, adapt to a new host and sometimes spread. This leads to a pandemic situation for HIV-1 or an endemic one for HTLV-1. Here, we present the available data on the discovery, epidemiology, cross-species transmission and molecular virology of the recently discovered HTLV-3 and HTLV-4 deltaretroviruses, as well as the simian foamy retroviruses present in different human populations at risk, especially in central African hunters. We discuss also the natural history in humans of these retroviruses of zoonotic origin (magnitude and geographical distribution, possible inter-human transmission). In Central Africa, the increase of the bushmeat trade during the last decades has opened new possibilities for retroviral emergence in humans, especially in immuno-compromised persons.

Novel simian foamy virus infections from multiple monkey species in women from the Democratic Republic of Congo

Background

Zoonotic transmission of simian retroviruses in Central Africa is ongoing and can result in pandemic human infection. While simian foamy virus (SFV) infection was reported in primate hunters in Cameroon and Gabon, little is known about the distribution of SFV in Africa and whether human-to-human transmission and disease occur. We screened 3,334 plasmas from persons living in rural villages in central Democratic Republic of Congo (DRC) using SFV-specific EIA and Western blot (WB) tests. PCR amplification of SFV polymerase sequences from DNA extracted from buffy coats was used to measure proviral loads. Phylogenetic analysis was used to define the NHP species origin of SFV. Participants completed questionnaires to capture NHP exposure information.

Results

Sixteen (0.5%) samples were WB-positive; 12 of 16 were from women (75%, 95% confidence limits 47.6%, 92.7%). Sequence analysis detected SFV in three women originating from Angolan colobus or red-tailed monkeys; both monkeys are hunted frequently in DRC. NHP exposure varied and infected women lived in distant villages suggesting a wide and potentially diverse distribution of SFV infections across DRC. Plasmas from 22 contacts of 8 WB-positive participants were all WB negative suggesting no secondary viral transmission. Proviral loads in the three women ranged from 14 – 1,755 copies/10⁵ cells.

Conclusions

Our study documents SFV infection in rural DRC for the first time and identifies infections with novel SFV variants from Colobus and red-tailed monkeys. Unlike previous studies, women were not at lower risk for SFV infection in our population, providing opportunities for spread of SFV both horizontally and vertically. However, limited testing of close contacts of WB-positive persons did not identify human-to-human transmission. Combined with the broad behavioral risk and distribution of NHPs across DRC, our results suggest that SFV infection may have a wider geographic distribution within DRC. These results also reinforce the potential for an increased SFV prevalence throughout the forested regions of Africa where humans and simians co-exist. Our finding of endemic foci of SFV infection in DRC will facilitate longitudinal studies to determine the potential for person-to-person transmissibility and pathogenicity of these zoonotic retroviral infections.

Ethnoprimatology and the Anthropology of the Human-Primate Interface

Humans are literal and figurative kin to other primates, with whom many of us coexist in diverse social, ecological, symbolic, conflictual, and even hopeful contexts. Anthropogenic action is changing global and local ecologies as fast as, or faster than, we can study them. Ethnoprimatology, the combining of primatological and anthropological practice and the viewing of humans and other primates as living in integrated and shared ecological and social spaces, is becoming an increasingly popular approach to primate studies in the twenty-first century. This approach plays a core linking role between anthropology and primate studies and may enable us to more effectively assess, and better understand, the complex ecologies and potential for sustainability in human–other primate communities. Here I review the basic theoretical underpinnings, historical contexts, and a selection of current research outcomes for the ethnoprimatological endeavor and indicate what this approach can tell us about human–other primate relations in the Anthropocene.

Cross-species transmission of simian retroviruses: how and why they could lead to the emergence of new diseases in the human population

The HIV-1 group M epidemic illustrates the extraordinary impact and consequences resulting from a single zoonotic transmission. Exposure to blood or other secretions of infected animals, through hunting and butchering of bushmeat, or through bites and scratches inflicted by pet nonhuman primates (NHPs), represent the most plausible source for human infection with simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus (STLV) and simian foamy virus. The chance for cross-species transmissions could increase when frequency of exposure and retrovirus prevalence is high. According to the most recent data, human exposure to SIV or STLV appears heterogeneous across the African countries surveyed. Exposure is not sufficient to trigger disease: viral and host molecular characteristics and compatibility are fundamental factors to establish infection. A successful species jump is achieved when the pathogen becomes transmissible between individuals within the new host population. To spread efficiently, HIV likely required changes in human behavior. Given the increasing exposure to NHP pathogens through hunting and butchering, it is likely that SIV and other simian viruses are still transmitted to the human population. The behavioral and socio-economic context of the twenty-first century provides favorable conditions for the emergence and spread of new epidemics. Therefore, it is important to evaluate which retroviruses the human population is exposed to and to better understand how these viruses enter, infect, adapt and spread to its new host.

Frequent and recent human acquisition of simian foamy viruses through apes' bites in central Africa

Human infection by simian foamy viruses (SFV) can be acquired by persons occupationally exposed to non-human primates (NHP) or in natural settings. This study aimed at getting better knowledge on SFV transmission dynamics, risk factors for such a zoonotic infection and, searching for intra-familial dissemination and the level of peripheral blood (pro)viral loads in infected individuals. We studied 1,321 people from the general adult population (mean age 49 yrs, 640 women and 681 men) and 198 individuals, mostly men, all of whom had encountered a NHP with a resulting bite or scratch. All of these, either Pygmies (436) or Bantus (1085) live in villages in South Cameroon. A specific SFV Western blot was used and two nested PCRs (polymerase, and LTR) were done on all the positive/borderline samples by serology. In the general population, 2/1,321 (0.2%) persons were found to be infected. In the second group, 37/198 (18.6%) persons were SFV positive. They were mostly infected by apes (37/39) FV (mainly gorilla). Infection by monkey FV was less frequent (2/39). The viral origin of the amplified sequences matched with the history reported by the hunters, most of which (83%) are aged 20 to 40 years and acquired the infection during the last twenty years. The (pro)viral load in 33 individuals infected by a gorilla FV was quite low (<1 to 145 copies per 10⁵ cells) in the peripheral blood leucocytes. Of the 30 wives and 12 children from families of FV infected persons, only one woman was seropositive in WB without subsequent viral DNA amplification. We demonstrate a high level of recent transmission of SFVs to humans in natural settings specifically following severe gorilla bites during hunting activities. The virus was found to persist over several years, with low SFV loads in infected persons. Secondary transmission remains an open question.

Most of the viral pathogens that have emerged in humans during the last decades have a zoonotic origin. After the initial interspecies transmission, these viruses have followed different evolutionary routes and have spread among humans through distinct mechanisms. The understanding of the initial steps of the emergence of several viruses and associated diseases often remains quite poor. Human infection by simian foamy viruses (SFV) can be acquired by persons occupationally exposed to non-human primates (NHP) or in natural settings. Epidemiological and microbiological studies in specific high-risk populations are necessary to gain new insights into the early events of the emergence process, and the potential to spread or cause disease among humans. The present study found that hunting is still a very common and risky activity for SFV infection in forest areas of South Cameroon. Indeed, recent interspecies transmission of SFVs to young adults is still very frequent, as 1 person out of 5 among the hunters who have reported a bite or scratch by a non-human primate and 2 persons out of a thousand in the general population are persistently infected by a SFV, mostly from an ape. Secondary transmission to other family members and presence of a disease in infected persons are still open questions that are being investigated.

Primates and primatologists: social contexts for interspecies pathogen transmission

Humans and nonhuman primates (NHP) interact in a variety of contexts. The frequency, duration, and intensity of interspecies interaction influence the likelihood that contact results in cross-species transmission of infectious agents. In this study, we present results of a cross-sectional survey of attendees at a national conference of primatologists, characterizing their occupational exposures to NHP. Of 116 individuals who participated in the study, 68.1% reported having worked with NHP in a field setting, 68.1% in a laboratory setting, and 24.1% at a zoo or animal sanctuary. Most subjects (N=98, 84.5%) reported having worked with multiple NHP taxa, including 46 (39.7%) who had worked with more than five distinct taxa. Sixty-nine subjects (59.5%) recalled having been scratched by a NHP and 48 (41.1%) had been bitten; 32 subjects reporting being bitten more than once. Eleven subjects (9.5%) reported having been injured by a needle containing NHP tissue or body fluids. We conclude that primatologists are at high risk for exposure to NHP-borne infectious agents. Furthermore, primatologists' varied occupational activities often bring them into contact with multiple NHP species in diverse contexts and geographic areas, over extended periods of time, making them a unique population with respect to zoonotic and anthropozoonotic disease risk.

Rabies post-exposure prophylaxis in travellers returning from Bali, Indonesia, November 2008 to March 2010

Since 2008, when the outbreak of rabies in Bali began, 45 patients have attended GeoSentinel or EuroTravNet sites for rabies post-exposure prophylaxis (PEP), representing 12.6% of all travellers seen for PEP in all network clinics during the same time period. This suggests that Bali is emerging as a commonly visited destination among travellers presenting for rabies PEP. The data demonstrate that the majority of animal-related injuries in travellers returning from Bali are associated with exposure to monkeys, and not dog bites/scratches. The clinical implications of this are discussed.

Ethical issues faced by field primatologists: asking the relevant questions

Field primatologists face unusual ethical issues. We study animals rather than people and receive research approval from animal care rather than ethics committees. However, animal care evaluation forms are developed from concerns about laboratory animal research and are based on the "Three R's" for humane treatment of captive experimental subjects (replacement, reduction and refinement), which are only debatably relevant to field research. Scientists who study wild, free-ranging primates in host countries experience many ethical dilemmas seldom dealt with in animal care forms. This paper reviews the ethical issues many field primatologists say they face and how these might be better addressed by animal care forms. The ethical issues arising for field researchers are divided into three categories: "Presence, Protocols and People" and for each the most frequent issues are described. The most commonly mentioned ethical concern arising from our presence in the field is the possibility of disease transmission. Although most primate field studies employ only observational protocols, the practice of habituating our study animals to close human presence is an ethical concern for many since it can lessen the animals' fear of all humans, thereby facilitating undesirable behaviors (e.g., crop-raiding) and rendering them vulnerable to harm. Field primatologists who work in host countries must observe national laws and local traditions. As conservationists, primatologists must often negotiate between the resource needs and cultural practices of local people and the interests of the nonhuman primates. Many say they face more ethical dilemmas arising from human interactions than from research on the animals per se. This review concludes with suggestions for relevant questions to ask on animal care forms, and actions that field primatologists can take to better inform animal care committees about the common ethical issues we experience as well as how to develop guidelines for addressing them.

Synanthropic primates in Asia: potential sentinels for environmental toxins

Macaques are similar to humans both physiologically and behaviorally. In South and Southeast Asia they are also synanthropic, ecologically associated with humans. Synanthropy with humans raises the possibility that macaques come into contact with anthropogenic toxicants, such as lead and mercury, and might be appropriate sentinels for human exposures to certain toxic materials. We measured lead (Pb) and mercury (Hg) levels and characterized the stable isotopic compositions of delta(15)N and delta(13)C in hair from three groups of free-ranging macaques at the Swoyambhu temple in Kathmandhu, Nepal, an urban population that has abundant contact with humans. Hair lead levels were significantly higher among young macaques and differed among the three groups of macaques that were sampled. Hair Hg levels were low. No statistical association was found between stable isotopic compositions (delta(15)N and delta(13)C) and Pb and Hg levels. Our data did not find evidence that lead levels were associated with diet. We conclude that, in this population of macaques, behavioral and/or physiologic factors may play a significant role in determining exposure to lead. Chemical analysis of hair is a promising, noninvasive technique for determining exposure to toxic elements in free-ranging nonhuman primates.

Simian foamy virus infection in humans: prevalence and management

Simian foamy viruses (SFVs) are highly prevalent in all nonhuman primate species and can infect humans following occupational and non-occupational exposure to infected animals and their tissues, blood or body fluids. Virus transmission results in a stable, persistent infection that seems to be latent. SFV infections are thus far nonpathogenic, with no evidence of adverse clinical outcome in their natural nonhuman primate hosts or by experimental injection in animals and upon cross-species transmission in humans. Since the emergence of pathogenic viruses from nonpathogenic viruses upon cross-species infection is well-documented for several retroviruses, it is prudent to take necessary precautions to deter SFV infections in humans. These steps will help prevent the emergence of a novel pathogen and reduce the risk of transmission of another potential pathogenic human retrovirus.

Interactions between visitors and Formosan macaques (Macaca cyclopis) at Shou-Shan Nature Park, Taiwan

Ecotourism involving feeding wildlife has raised public attention and is a controversial issue, especially concerning nonhuman primates. Between July 2002 and April 2005, the behavior of monkeys and tourists was collected through scan samplings, focal samplings and behavior samplings at the Shou-Shan Nature Park located in Taiwan's second largest city--Kaohsiung. In addition, the number of tourists and monkeys was counted in different hours and places within the park. Four hundred visitors were interviewed using a questionnaire to gather data on sex, age, purpose and frequency of visit to the park. The number of tourists was significantly higher during weekends than in weekdays in all locations. Humans dominated in the initiation of interspecies interactions--the overall ratio of human-initiated and monkey-initiated interactions was 2.44:1. Human-monkey conflicts accounted for only 16.4% of the total interactions (n=2,166), and adult human males and adult male macaques participated in higher rates than other age/sex groups in these conflicts. Visitors showed more affiliative behavior (15.9%) than agonistic behavior (8%) toward the macaques. In response to visitors' threat or attack, the Formosan macaques mostly showed submissive behavior with bared teeth, squealed or ran away to avoid confrontation (69.1%)--only few responded with counteraggression (18.7%). This study for the first time provided evidence that food provisioning increased both the frequency and duration of aggression among Formosan macaques (P<0.001). During food provisioning, the average frequency and the duration of agonistic events of macaques were more than 4 times higher compared with those without food provisioning. The average frequency of food provision by tourists was 0.73 times/hr--more than twice the incident that monkeys grabbed the food from tourists (0.34 times/hr). If people refrain from feeding monkeys and destroying the city park's natural vegetation, monkeys can be used to educate public about nature conservation in an urban setting.

Diverse contexts of zoonotic transmission of simian foamy viruses in Asia

These infections are likely prevalent among persons who live or work near nonhuman primates.

In Asia, contact between persons and nonhuman primates is widespread in multiple occupational and nonoccupational contexts. Simian foamy viruses (SFVs) are retroviruses that are prevalent in all species of nonhuman primates. To determine SFV prevalence in humans, we tested 305 persons who lived or worked around nonhuman primates in several South and Southeast Asian countries; 8 (2.6%) were confirmed SFV positive by Western blot and, for some, by PCR. The interspecies interactions that likely resulted in virus transmission were diverse; 5 macaque taxa were implicated as a potential source of infection. Phylogenetic analysis showed that SFV from 3 infected persons was similar to that from the nonhuman primate populations with which the infected persons reported contact. Thus, SFV infections are likely to be prevalent among persons who live or work near nonhuman primates in Asia.

Characterizing human-macaque interactions in Singapore

Previous studies have noted substantial human-macaque interactions involving physical contact in Bali, Indonesia; Gibraltar; and Mt. Emei, China [Fuentes, American Journal of Primatology 68:880-896, 2006; Zhao, Tibetan macaques, visitors, and local people at Mt. Emei: problems and countermeasures. In: Paterson and Wallis, editor. Commensalism and conflict: the human-primate interface. Norman, OK: American Society of Primatologists. p 376-399, 2005]. The aim of this study was to conduct preliminary observations in order to begin to characterize interaction patterns between humans and long-tailed macaques (Macaca fascicularis) in Singapore. Unlike Bali, Gibraltar, and Mt. Emei, Singapore occasionally enforces fines and penalties and engages in an education campaign in an effort to minimize physical contact between humans and macaques. Observers stationed at two sites in Singapore conducted 92 5 hr of observation that included 730 human-macaque interactions over 16 days. Data recorded include interaction characteristics, demographic and behavioral variables, presence of feeding by humans, and presence of automobiles. Although feeding by humans was relatively infrequent overall, it generally occurred most often by individuals in cars and when human children were present. Data analysis suggests that interactions involving physical contact between macaques and humans are rare in Singapore, in contrast to the findings from Bali, Gibraltar, and Mt. Emei. This low level of physical contact suggests a low risk of macaque-human pathogen transmission in Singapore.

Macaque models of human infectious disease

Macaques have served as models for more than 70 human infectious diseases of diverse etiologies, including a multitude of agents—bacteria, viruses, fungi, parasites, prions. The remarkable diversity of human infectious diseases that have been modeled in the macaque includes global, childhood, and tropical diseases as well as newly emergent, sexually transmitted, oncogenic, degenerative neurologic, potential bioterrorism, and miscellaneous other diseases. Historically, macaques played a major role in establishing the etiology of yellow fever, polio, and prion diseases. With rare exceptions (Chagas disease, bartonellosis), all of the infectious diseases in this review are of Old World origin. Perhaps most surprising is the large number of tropical (16), newly emergent (7), and bioterrorism diseases (9) that have been modeled in macaques. Many of these human diseases (e.g., AIDS, hepatitis E, bartonellosis) are a consequence of zoonotic infection. However, infectious agents of certain diseases, including measles and tuberculosis, can sometimes go both ways, and thus several human pathogens are threats to nonhuman primates including macaques. Through experimental studies in macaques, researchers have gained insight into pathogenic mechanisms and novel treatment and vaccine approaches for many human infectious diseases, most notably acquired immunodeficiency syndrome (AIDS), which is caused by infection with human immunodeficiency virus (HIV). Other infectious agents for which macaques have been a uniquely valuable resource for biomedical research, and particularly vaccinology, include influenza virus, paramyxoviruses, flaviviruses, arenaviruses, hepatitis E virus, papillomavirus, smallpox virus, Mycobacteria, Bacillus anthracis, Helicobacter pylori, Yersinia pestis, and Plasmodium species. This review summarizes the extensive past and present research on macaque models of human infectious disease.

Exposure to wild primates among HIV-infected persons

HIV-1 is an immunosuppressive pathogen. Our behavioral data for 191 HIV-1-infected rural Cameroonians show frequent exposure to nonhuman primates through activities such as hunting and butchering. Immunosuppression among persons exposed to body fluids of wild nonhuman primates could favor the process of adaptation and subsequent emergence of zoonotic pathogens.

Effects of age and oral disease on systemic inflammatory and immune parameters in nonhuman primates

This report evaluated systemic inflammatory and immune biomarkers in a cohort of Macaca mulatta (rhesus monkeys) maintained as a large family social unit, including an age range from <1 year to >24 years. We hypothesized that the systemic host responses would be affected by the age, gender, and clinical oral presentation of the population, each contributing to inflammatory and immune responses that would reflect chronic oral infections. The results demonstrated that the prevalence and severity of periodontitis, including missing teeth, increased significantly with age. Generally, minimal differences in clinical parameters were noted between the genders. Systemic inflammatory mediators, including acute-phase reactants, prostaglandin E(2) (PGE(2)), cytokines/chemokines, and selected matrix metalloproteinases (MMP), demonstrated significant differences among the various age groups of animals. Levels of many of these were increased with age, although PGE(2), RANTES, bactericidal permeability-inducing factor (BPI), MMP-1, and MMP-9 levels were significantly increased in the young group ( approximately 1 to 3 years old) relative to those for the older animals. We observed that in the adult and aged animals, levels of the systemic inflammatory mediators related to gingival inflammation and periodontal tissue destruction were significantly elevated. Serum antibody levels in response to a battery of periodontal pathogens were generally lower in the young animals, <50% of those in the adults, and were significantly related to aging in the cohort. The levels of antibodies, particularly those to Porphorymonas gingivalis, Fusobacterium nucleatum, and Tannerella forsythia, were most significantly elevated in animals with periodontal disease, irrespective of the age of the animal. These results provide a broad description of oral health and host responses in a large cohort of nonhuman primates from very young animals to the aged of this species. The findings afford a base of data with which to examine the ontogeny of host responses at mucosal sites, such as the gingival tissues.

Simian foamy virus transmission from apes to humans, rural Cameroon

Bites from apes efficiently transmit the foamy virus to humans in natural settings in central Africa.

Simian virus infections of humans are an increasing public health concern. Simian foamy virus (SFV) infections have been reported in persons occupationally exposed to nonhuman primates and in a few hunters in Cameroon. To better understand this retroviral zoonosis in natural settings, we studied persons who lived in southern Cameroon, near nonhuman primate habitats. First we studied a general population of 1,164 adults; 4 were SFV positive according to serologic and molecular assays. Then we studied 85 persons who reported having been bitten or scratched by nonhuman primates; 7/29 (24.1%) of those who had contact with apes (gorillas or chimpanzees) were SFV positive, compared with only 2/56 (3.6%) of those who had had contact with monkeys. These data demonstrate efficient transmission of SFVs to humans in natural settings in central Africa, specifically following ape bites, and viral persistence in the human host.

Emergence of simian foamy viruses in humans: facts and unanswered questions

A large proportion of viral pathogens that have emerged in humans are considered to have originated in animals. Simian viral infections of humans represent an increasing public health concern. This is well illustrated by retroviruses such as HIV-1/2 and human T-cell lymphotropic virus (HTLV)-1, which have a unique ability to cross species, adapt to a new host and spread. In this short review, we will present the currently available data on the transmission of the simian foamy retroviruses (SFVs) to humans. Indeed, recent data indicate the presence of these exogenous retroviruses, of the Spumaretrovirinae subfamily and of the Spumavirus genus, in individuals occupationally exposed to nonhuman primates (animal caretaker, veterinarian, zoo worker) and in individuals having contact with apes and monkeys, such as hunters in Central Africa. The main unanswered questions concerning the natural history of such SFVs in humans, for instance, their magnitude and geographical distribution, their interhuman transmissibility and their disease association and pathogenicity are discussed in this review.

Exposure to wild primates among HIV-infected persons

HIV-1 is an immunosuppressive pathogen. Our behavioral data for 191 HIV-1-infected rural Cameroonians show frequent exposure to nonhuman primates through activities such as hunting and butchering. Immunosuppression among persons exposed to body fluids of wild nonhuman primates could favor the process of adaptation and subsequent emergence of zoonotic pathogens.

Sensitive assays for simian foamy viruses reveal a high prevalence of infection in commensal, free-ranging Asian monkeys

Foamy viruses (FV) are retroviruses that naturally infect many hosts, including most nonhuman primates (NHPs). Zoonotic infection by primate FV has been documented in people in Asia who reported contact with free-ranging macaques. FV transmission in Asia is a concern, given abundant human-NHP contact, particularly at monkey temples and in urban settings. We have developed three assays capable of detecting the presence of FV in Asian NHP species that are commensal with humans: enzyme-linked immunosorbent assay (ELISA), Western blot assays using recombinant viral Gag protein, and an indicator cell line that can detect macaque FV. The recombinant ELISA correlates very well with the presence of FV sequences detected by PCR. We have used these assays to demonstrate both that FV is highly prevalent among free-ranging NHPs and that seroconversion occurs at a young age in these animals. These assays should also prove useful for large-scale analysis of the prevalence of FV infections in human populations in Asia that are commensal with free-ranging NHPs.

Temple monkeys and health implications of commensalism, Kathmandu, Nepal

Humans in contact with macaques risk exposure to enzootic primateborne viruses.

The threat of zoonotic transmission of infectious agents at monkey temples highlights the necessity of investigating the prevalence of enzootic infectious agents in these primate populations. Biological samples were collected from 39 rhesus macaques at the Swoyambhu Temple and tested by enzyme-linked immunosorbent assay, Western blot, polymerase chain reaction, or combination of these tests for evidence of infection with rhesus cytomegalovirus (RhCMV), Cercopithecine herpesvirus 1 (CHV-1), simian virus 40 (SV40), simian retrovirus (SRV), simian T-cell lymphotropic virus (STLV), simian immunodeficiency virus (SIV), and simian foamy virus (SFV). Antibody seroprevalence was 94.9% to RhCMV (37/39), 89.7% to SV40 (35/39), 64.1% to CHV-1 (25/39), and 97.4% to SFV (38/39). Humans who come into contact with macaques at Swoyambhu risk exposure to enzootic primateborne viruses. We discuss implications for public health and primate management strategies that would reduce contact between humans and primates.