Considering human–primate transmission of measles virus through the prism of risk analysis

Gastro-intestinal parasites of urban rhesus macaques (Macaca mulatta) in the Kathmandu Valley, Nepal

Intestinal parasitic infections such as amoebiasis, ascariasis, hookworm infection, and trichuriasis are the most common infections among non-human primates (NHPs). There are always the possibilities of transmission these parasites between humans and NHPs. Multiple groups of rhesus macaques (Macaca mulatta) live in the urban area of Kathmandu Valley near human settlements, however the gastrointestinal (GI) parasitic infections in those macaques are understudied. This study aimed to explore the GI parasites in free-ranging macaques from Pashupatinath, Swayambhunath, Tripureshwor, Nilbarahi temples and a group of captive rhesus macaques in the Central Zoo, Kathmandu. Fecal samples were collected from the macaques between October 2021 to September 2022 and assessed for parasites by the both wet mount method and concentration technique. There is high prevalence of GI parasite infection; out of 121 fecal samples examined, 87.6% of samples were positive. Six species of protozoans and eight species of helminths were identified from the fecal samples including the first report of Iodamoeba butschlii in monkeys of Nepal. Among the protozoan parasites, Entamoeba coli (54.71%) showed the highest prevalence followed by Balantioides coli (44.33%), E. histolytica (19.81%), and Iodamoeba butschlii (10%). Among the helminths, Trichuris spp. (31.13%) and Strongyloides spp. (31.13%) showed the highest prevalence followed by Hookworm (24.52%), and Strongyle spp. (23.58%). The likelihood ratio test suggested that the prevalence differed significantly with the seasons for Iodamoeba butschlii, Giardia spp., Strongyles spp., Hookworm, and Trichostrongylus spp. The prevalence of E. histolytica, E. coli, Iodamoeba. butschlii, Trichuris spp., Trichostrongylus spp., and Unknown spp.1 differed with sampling localities. The high prevalence of GI parasites found in the macaques living in the densely urbanized Kathmandu presents a potential threat to humans and warrants further study as well as increased education of the public and management of the human-macaque interface in the urban landscape of the Valley.

Association between seroprevalence of measles virus in monkeys and degree of human-monkey contact in Bangladesh

Measles infections can cause significant morbidity and mortality in human and monkey populations. The endemicity of measles in human populations and viral circulation within populations of free-living monkeys may have important repercussions for potential zoonotic transmission events and for the long-term health of monkey populations. Yet, there has not yet been a rigorous investigation of the dynamics of measles transmission where human and monkey populations coexist. In this study, to determine the difference in seroprevalence of the measles virus across different contexts of human-monkey contact, we analyzed serum samples collected from 56 apparently healthy Macaca mulatta monkeys who occupied diverse contexts, with different degrees of human-monkey contact, in Bangladesh. This is the first report of measles virus seroprevalence in monkeys in Bangladesh. We found a clear association between measles virus seropositivity in monkeys and the context in which they interact with humans. Seroprevalence was the lowest in wild areas (0.0%) and increased in shrines (4.8%), urban areas (5.9%), and was highest among monkeys who are used as performance animals (50.0%). This work suggests that a One Health approach informed by local interspecies transmission dynamics is necessary to develop strategies that both improve measles vaccination coverage, achieve long-term surveillance in monkey populations, and prevent measles spillback to monkeys. This approach aims to inform conservation efforts and protect the long-term health of human and monkey populations.

Measles in non-human primates

It is six decades since the measles vaccine was first introduced, and yet we continue to see frequent outbreaks of this disease occurring all over the world. Many non-human primate (NHP) species, including apes, are susceptible to the measles virus. Spontaneous measles outbreaks have been described in a number of zoos and primate centers worldwide. Research into the spontaneous and experimental infection of laboratory primates with measles represents an invaluable source of information regarding the biology and pathogenesis of this virus and continues to be an irreplaceable and unique tool for testing vaccines and treatments. The purpose of this literature review is to summarize and analyze published data on the circulation of the measles virus among free-living synanthropic and captive primate populations, as well as the results of experiments that have modeled this infection in NHPs.

Detection of viruses from feces of wild endangered Macaca maura: a potential threat to moor macaque survival and for zoonotic infection

BACKGROUND

To date, there is a scarcity of information and literature on Macaca maura health status relative to viral diseases. The objectives of the present study were to investigate on the potential spread of enteric and non-enteric viruses shed in the environment through a wild macaque feces and to understand the possible interrelation in the spread of zoonotic viruses in a poorly studied geographical area, the Sulawesi Island. This study will also contribute providing useful information on potential threats to the health of this endangered species.

METHODS

The sampling was conducted between 2014 and 2016 in the Bantimurung Bulusaraung National Park, in the south of the Sulawesi Island and non-invasive sampling methods were used to collect fresh stools of the M. maura, one of the seven macaque species endemic to the island of Sulawesi, Indonesia. The population under study consisted in two wild, neighboring social macaque groups with partially overlapping home ranges; twenty-four samples were collected and examined using negative staining electron microscopy and a panel of PCR protocols for the detection of ten RNA and two DNA viruses.

RESULTS

Viral particles resembling parvovirus (5 samples), picornavirus (13 samples) and calicivirus (13 samples) were detected by electron microscopy whereas the PCR panel was negative for the 12 viruses investigated, except for one sample positive for a mosquito flavivirus. The results did not correlate with animal sex; furthermore, because all of the animals were clinically healthy, it was not possible to correlate feces consistency with viral presence.

CONCLUSIONS

As information on viral infections in wild moor macaques remains limited, further studies are yet required to identify the fecal-oral and blood transmitted potentially zoonotic viruses, which may infect the moor macaque and other macaque species endemic to the South Sulawesi Island.

Updates on Measles Incidence and Eradication: Emphasis on the Immunological Aspects of Measles Infection

Measles is an RNA virus infectious disease mainly seen in children. Despite the availability of an effective vaccine against measles, it remains a health issue in children. Although it is a self-limiting disease, it becomes severe in undernourished and immune-compromised individuals. Measles infection is associated with secondary infections by opportunistic bacteria due to the immunosuppressive effects of the measles virus. Recent reports highlight that measles infection erases the already existing immune memory of various pathogens. This review covers the incidence, pathogenesis, measles variants, clinical presentations, secondary infections, elimination of measles virus on a global scale, and especially the immune responses related to measles infection.

Travel medicine meets conservation medicine in St. Kitts: Disinhibition, cognitive-affective inconsistency, and disease risk among vacationers around green monkeys (Chlorocebus sabaeus)

Despite concern about environmental protection, travelers often underestimate the contribution they may have to disease transmission to other species, as well as the risk of becoming infected themselves. Tourists in general tend to accept more physical risks when traveling than when at home, and much of this can be blamed on the temporary loss of situational awareness and loss of inhibition with a corresponding relaxed attitude toward safety. To better understand environmental attitudes and travel health knowledge and behaviors, a detailed survey of adult tourists was distributed on the island of St. Kitts, home to many green monkeys. Data from 1097 respondents were collected at two locations where cruise ship passengers typically visit the island. Results revealed that even though individuals with more positive environmental attitudes were more willing to take steps to mitigate tourism-related disease transmission, they were also more likely to report wanting to touch or feed a monkey/ape. Similarly, those more willing to prevent the spread of diseases (e.g., wear a mask and report any illnesses to park authorities) were actually more likely to want to touch or feed a monkey/ape. The human desire for physical contact with other species may be partly the result of biophilia, emotionally arousing events (like contact with exotic species) that can lead to further disinhibition, and social media platforms that provide opportunities for exhibitionism. The attitude-behavior incongruency identified here may also be explained through cognitive-affective inconsistency: environmentally-oriented individuals believe that it is prudent to take steps to prevent zoonotic disease transmission but also desire to touch or feed exotic species as it may be emotionally rewarding. Individuals for whom physically interacting with monkeys/apes may be emotionally rewarding may not alter their behavior in response to cognitive means of persuasion; techniques aimed at appealing to emotions may be more effective.

Should we be concerned about COVID-19 with nonhuman primates?

The coronavirus disease 2019 pandemic has radically changed the human activities worldwide. Although we are still learning about the disease, it is necessary that primatologists, veterinarians, and all that are living with nonhuman primates (NHP) be concerned about the probable health impacts as these animals face this new pandemic. We want to increase discussion with the scientific community that is directly involved with these animals, because preliminary studies report that NHP may become infected and develop symptoms similar to those in human beings.

Modified Dose Efficacy Trial of a Canine Distemper-Measles Vaccine for Use in Rhesus Macaques (Macaca mulatta)

Measles virus causes a highly infectious disease in NHP. Clinical signs range from asymptomatic to fatal, although measles virus is most well-known for its characteristic generalized maculopapular rash. Along with appropriate quarantine practices, restricted human access, and appropriate personal protective equipment, vaccines are used to combat the risk of infection. The canine distemper-measles vaccine (CDMV), administered at the manufacturer's standard dose (1.0 mL IM), has been shown to be effective against clinical measles disease in rhesus macaques (Macaca mulatta). The goal of the current study was to test whether doses smaller than the manufacturer's recommended dose stimulated adequate antibody production to protect against infection. We hypothesized that either 0.25 or 0.5 mL IM of CDMV would stimulate antibody production comparable to the manufacturer's recommended dose. We found that the 0.25-mL dose was less effective at inducing antibodies than either the standard (1.0 mL) or 0.5-mL dose, which both yielded similar titers. The primary implication of this study informs balancing resource allocation and providing efficacious immunity. By using half the manufacturer-recommended dose, the 50% cost reduction may provide sufficient monetary incentive to implement, maintain, or modify measles vaccination programs at NHP facilities.

Reemergence of Reston ebolavirus in Cynomolgus Monkeys, the Philippines, 2015

In August 2015, a nonhuman primate facility south of Manila, the Philippines, noted unusual deaths of 6 cynomolgus monkeys (Macaca fascicularis), characterized by generalized rashes, inappetence, or sudden death. We identified Restonebolavirus (RESTV) infection in monkeys by using serologic and molecular assays. We isolated viruses in tissues from infected monkeys and determined viral genome sequences. RESTV found in the 2015 outbreak is genetically closer to 1 of the 4 RESTVs that caused the 2008 outbreak among swine. Eight macaques, including 2 also infected with RESTV, tested positive for measles. Concurrently, the measles virus was circulating throughout the Philippines, indicating that the infection of the macaques may be a reverse zoonosis. Improved biosecurity measures will minimize the public health risk, as well as limit the introduction of disease and vectors.

Measles

Measles is a highly contagious disease that results from infection with measles virus and is still responsible for more than 100 000 deaths every year, down from more than 2 million deaths annually before the introduction and widespread use of measles vaccine. Measles virus is transmitted by the respiratory route and illness begins with fever, cough, coryza, and conjunctivitis followed by a characteristic rash. Complications of measles affect most organ systems, with pneumonia accounting for most measles-associated morbidity and mortality. The management of patients with measles includes provision of vitamin A. Measles is best prevented through vaccination, and the major reductions in measles incidence and mortality have renewed interest in regional elimination and global eradication. However, urgent efforts are needed to increase stagnating global coverage with two doses of measles vaccine through advocacy, education, and the strengthening of routine immunisation systems. Use of combined measles-rubella vaccines provides an opportunity to eliminate rubella and congenital rubella syndrome. Ongoing research efforts, including the development of point-of-care diagnostics and microneedle patches, will facilitate progress towards measles elimination and eradication.

Urban primate ranging patterns: GPS-collar deployments for Macaca fascicularis and M. sylvanus

The global increase in urbanization is leading to heavier interface between humans and wildlife. Within these anthropogenic landscapes, little is known about ranging patterns, particularly with regard to urban primates. Here we present the results of the first long-term deployment of multiple GPS collars on two species of macaques to investigate the impacts of urbanization on urban primate ranging patterns in Singapore and Gibraltar. Collars data acquisition were excellent with respect to the amount, quality, and accuracy of data collected; however, remote connectivity and drop-off functionality was poor across all deployments. Analyses highlighted high variability in ranging patterns between individuals within each species that aligned with access to human food resources and patterns of tourism. Individuals from troops with less access to human food had much larger home, core, and day ranges relative to those with regular provisioning or raiding opportunities. Almost no temporal range overlap was observed between any focal individuals at either site and spatial overlap was low for all but two troops at each site. We found no relationship between anthropogenic schedules and changes in ranging patterns. Significant seasonal variation existed for daily path length and day range size for both the Singapore long-tailed and the Gibraltar Barbary macaques, with long-tailed macaques increasing their range during the equatorial monsoon season and Barbary macaques increasing their range during drier, summer months. This study highlights how the behavioral plasticity found within the genus Macaca is reflected in ranging pattern variability within urban environments.

Retrospective serology study of respiratory virus infections in captive great apes

Great apes are extremely sensitive to infections with human respiratory viruses. In this study, we retrospectively analyzed sera from captive chimpanzees, gorillas and orang-utans. More than 1000 sera (403 chimpanzee, 77 gorilla, and 535 orang-utan sera) were analyzed for antibodies to the human respiratory viruses RSV (respiratory syncytial virus, hMPV (human metapneumovirus), H1N1 and H3N2 influenza A viruses, and influenza B virus. In all ape species high seroprevalences were found for RSV, hMPV, and influenza B virus. A high percentage of captive chimpanzees also showed evidence of influenza A H1N1 infections, and had low levels of H3N2 antibodies, while in sera from gorillas and orang-utans antibody levels to influenza A and B viruses were much lower or practically absent. Transmission of respiratory viruses was examined in longitudinal sera of young chimpanzees, and in chimpanzee sera taken during health checks. In young animals isolated cases of influenza infections were monitored, but evidence was found for single introductions followed by a rapid dissemination of RSV and hMPV within the group. Implementation of strict guidelines for handling and housing of nonhuman primates was shown to be an efficient method to reduce the introduction of respiratory infections in colonies of captive animals. RSV seroprevalence rates of chimpanzees remained high, probably due to circulating virus in the chimpanzee colony.

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.

Prevalence of Entamoeba nuttalli infection in wild rhesus macaques in Nepal and characterization of the parasite isolates

We have recently resurrected the name Entamoeba nuttalli Castellani, 1908 for a potentially virulent ameba isolate, P19-061405, obtained from a rhesus macaque in Kathmandu, Nepal. The ameba was morphologically indistinguishable from Entamoeba histolytica/Entamoeba dispar/Entamoeba moshkovskii, but located phylogenetically between E. histolytica and E. dispar. To evaluate the prevalence of E. nuttalli infection in wild rhesus macaques, 112 fecal samples were collected in four locations of the Kathmandu Valley. PCR analysis of DNA extracted from the feces showed positive rates of E. nuttalli, E. dispar, E. histolytica and E. moshkovskii of 51%, 12%, 0% and 0%, respectively. A total of 14 E. nuttalli isolates were obtained from four locations, of which 6 were established as axenic cultures. The sequences of the serine-rich protein gene of E. nuttalli isolates differed among four locations although no differences were found in the composition of sequence motifs. Isoenzyme pattern was analyzed in 8 isolates obtained from three locations. In hexokinase, the mobility of the slower migrating band was located between E. histolytica and E. dispar regardless of the culture conditions. These results demonstrate that E. nuttalli is highly prevalent in wild rhesus macaques in Nepal. Rhesus macaques appear to be one of the natural hosts and heterogeneity of the serine-rich protein gene might be useful for geographical typing of isolates.

Primates, Pathogens, and Evolution: A Context for Understanding Emerging Disease

The world is rife with potential pathogens. Of those that infect humans, it is estimated that roughly 20 % are of nonhuman primate origin. The same ease characterizes pathogen transmission in the other direction, from humans to nonhuman primates. This latter problem has increasingly serious ramifications for conservation efforts, as growing numbers of ecotourists and researchers serve as potential vectors of disease. Here, we present an analysis of major cross-species transmission events between human and nonhuman primates. In particular, we consider HIV and malaria as case studies in which nonhuman primate pathogens emerged and became permanent fixtures in human populations. The human practices that facilitate such events are considered, as well as the evolutionary consequences of these events. In addition, we describe human-to-nonhuman primate transmission events and discuss the potential of human pathogens to adapt to nonhuman primate hosts. The topic of emerging infections is addressed, in both human and nonhuman species, in light of changing patterns of contact and novel adaptations on the part of pathogens and hosts.

Characterizing the picornavirus landscape among synanthropic nonhuman primates in Bangladesh, 2007 to 2008

The term synanthropic describes organisms that thrive in human-altered habitats. Where synanthropic nonhuman primates (NHP) share an ecological niche with humans, cross-species transmission of infectious agents can occur. In Bangladesh, synanthropic NHP are found in villages, densely populated cities, religious sites, and protected forest areas. NHP are also kept as performing monkeys and pets. To investigate possible transmission of enteric picornaviruses between humans and NHP, we collected fecal specimens from five NHP taxa at16 locations in Bangladesh during five field sessions, from January 2007 to June 2008. Specimens were screened using real-time PCR assays for the genera Enterovirus, Parechovirus, and Sapelovirus; PCR-positive samples were typed by VP1 sequencing. To compare picornavirus diversity between humans and NHP, the same assays were applied to 211 human stool specimens collected in Bangladesh in 2007 to 2008 for acute flaccid paralysis surveillance. Picornaviruses were detected in 78 of 677 (11.5%) NHP fecal samples. Twenty distinct human enterovirus (EV) serotypes, two bovine EV types, six human parechovirus serotypes, and one virus related to Ljungan virus were identified. Twenty-five additional enteroviruses and eight parechoviruses could not be typed. Comparison of the picornavirus serotypes detected in NHP specimens with those detected in human specimens revealed considerable overlap. Strikingly, no known simian enteroviruses were detected among these NHP populations. In conclusion, enteroviruses and parechoviruses may be transmitted between humans and synanthropic NHP in Bangladesh, but the directionality of transmission is unknown. These findings may have important implications for the health of both human and NHP populations.

From the mouths of monkeys: detection of Mycobacterium tuberculosis complex DNA from buccal swabs of synanthropic macaques

Although the Mycobacterium tuberculosis complex (MTBC) infects a third of all humans, little is known regarding the prevalence of mycobacterial infection in nonhuman primates (NHP). For more than a century, tuberculosis has been regarded as a serious infectious threat to NHP species. Advances in the detection of MTBC open new possibilities for investigating the effects of this poorly understood pathogen in diverse populations of NHP. Here, we report results of a cross-sectional study using well-described molecular methods to detect a nucleic acid sequence (IS6110) unique to the MTBC. Sample collection was focused on the oral cavity, the presumed route of transmission of MTBC. Buccal swabs were collected from 263 macaques representing 11 species in four Asian countries and Gibraltar. Contexts of contact with humans included free ranging, pets, performing monkeys, zoos, and monkey temples. Following DNA isolation from buccal swabs, the polymerase chain reaction (PCR) amplified IS6110 from 84 (31.9%) of the macaques. In general, prevalence of MTBC DNA was higher among NHP in countries where the World Health Organization reports higher prevalence of humans infected with MTBC. This is the first demonstration of MTBC DNA in the mouths of macaques. Further research is needed to establish the significance of this finding at both the individual and population levels. PCR of buccal samples holds promise as a method to elucidate the mycobacterial landscape among NHP, particularly macaques that thrive in areas of high human MTBC prevalence.

Zoonotic diseases of primates

A zoonotic disease is transmissible from vertebrate animals to humans. This article focuses on pertinent zoonotic diseases that have to be taken into consideration when working with nonhuman primate (NHP) species. Many factors may influence the occurrence of these diseases. Human and NHPs share many similarities, not only anatomically but also physiologically. NHP are valuable models for many human infectious diseases; therefore, staff can be exposed to many potential pathogens. In general, the disease state of a primate can range from asymptomatic carrier to death from infection.

Risk analysis for measles reintroduction after global certification of eradication

BACKGROUND

Measles virus will continue to exist after certification of global eradication as virus stocks and infectious materials held in laboratories, in persistently and chronically infected individuals, and possibly in undetected foci of transmission. A literature search was undertaken to identify and evaluate the main risks for reintroduction of measles transmission in the absence of universal measles immunization.

METHODS

A qualitative risk assessment was conducted following a series of literature searches using the PubMed database.

RESULTS

If the criteria for global certification of eradication are stringent and require rigorous validation, then the risk of undetected measles transmission after certification is very low. Risk of unintentional reintroduction from any source, including persistent infections and laboratory materials is low to very low but depends on the extent of measles vaccine use. If immunization levels decrease, measles will become a credible agent for bioterrorism through intentional release.

CONCLUSIONS

Posteradication risks are low and should not deter any attempt at measles eradication. More information on measles transmission dynamics and the role of atypical infections is required to determine requirements for global certification of eradication. Posteradication risks would be minimized through development and implementation of an international risk management strategy, including requirements for a posteradication vaccine stockpile.

Biological feasibility of measles eradication

Recent progress in reducing global measles mortality has renewed interest in measles eradication. Three biological criteria are deemed important for disease eradication: (1) humans are the sole pathogen reservoir; (2) accurate diagnostic tests exist; and (3) an effective, practical intervention is available at reasonable cost. Interruption of transmission in large geographical areas for prolonged periods further supports the feasibility of eradication. Measles is thought by many experts to meet these criteria: no nonhuman reservoir is known to exist, accurate diagnostic tests are available, and attenuated measles vaccines are effective and immunogenic. Measles has been eliminated in large geographical areas, including the Americas. Measles eradication is biologically feasible. The challenges for measles eradication will be logistical, political, and financial.

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.

Terminal investment and senescence in rhesus macaques (Macaca mulatta) on Cayo Santiago

Long-lived iteroparous species often show aging-related changes in reproduction that may be explained by 2 non-mutually exclusive hypotheses. The terminal investment hypothesis predicts increased female reproductive effort toward the end of the life span, as individuals have little to gain by reserving effort for the future. The senescence hypothesis predicts decreased female reproductive output toward the end of the life span due to an age-related decline in body condition. Nonhuman primates are ideal organisms for testing these hypotheses, as they are long lived and produce altricial offspring heavily dependent on maternal investment. In this study, we integrated 50 years of continuous demographic records for the Cayo Santiago rhesus macaque (Macaca mulatta) population with new morphometric and behavioral data to test the senescence and terminal investment hypotheses. We examined relationships between maternal age and activity, mother and infant body condition, interbirth intervals, measures of behavioral investment in offspring, and offspring survival and fitness to test for age-associated declines in reproduction that would indicate senescence, and for age-associated increases in maternal effort that would indicate terminal investment. Compared with younger mothers, older mothers had lower body mass indices and were less active, had longer interbirth intervals, and spent more time in contact with infants, but had infants of lower masses and survival rates. Taken together, our results provide strong evidence for the occurrence of reproductive senescence in free-ranging female rhesus macaques but are also consistent with some of the predictions of the terminal investment hypothesis.

Emerging and reemerging infectious diseases of nonhuman primates in the laboratory setting

Despite numerous advances in the diagnosis and control of infectious diseases of nonhuman primates in the laboratory setting, a number of infectious agents continue to plague colonies. Some, such as measles virus and Mycobacterium tuberculosis, cause sporadic outbreaks despite well-established biosecurity protocols, whereas others, such as retroperitoneal fibromatosis-associated herpesvirus, have only recently been discovered, often as a result of immunosuppressive experimental manipulation. Owing to the unique social housing requirements of nonhuman primates, importation of foreign-bred animals, and lack of antemortem diagnostic assays for many new diseases, elimination of these agents is often difficult or impractical. Recognition of these diseases is therefore essential because of their confounding effects on experimental data, impact on colony health, and potential for zoonotic transmission. This review summarizes the relevant pathology and pathogenesis of emerging and reemerging infectious diseases of laboratory nonhuman primates.

Macaque-human interactions and the societal perceptions of macaques in Singapore

Humans and long-tailed macaques (Macaca fascicularis) interface in several locations in Singapore. We investigated six of these interface zones to assess the level of conflict between the two species. We observed macaque-to-human interactions and distributed questionnaires to residents and visitors of nature reserves. We observed an average of two macaque-to-human interactions per hour at the sites, which included affiliative or submissive behaviors (46.9%), aggression (19.1%), taking food and other items (18.5%) searching bins, cars, and houses (13.4%), and nonaggressive contact (2.1%). Two-thirds of interactions occurred when a human was carrying food or food cues, and one-quarter occurred when a human provoked macaques. Only 8% of interactions occurred without a clear human-triggered context. Our interview showed one-third of respondents experienced nuisance problems from macaques. They had items taken from them (50.5%) and received threats (31.9%). Residents reported more nuisance problems than visitors, and their perceptions toward macaques differed. Residents were more aware of the consequences of food provisioning and that there were regulations against feeding. Residents fed macaques less and held more negative sentiments toward macaques. Nearly half of the interviewed people held neutral attitudes toward macaques and only 26.2% of respondents thought conflict with macaques warranted urgent action. Nearly two-thirds of the respondents supported education programs to ameliorate human-macaque conflict, and less than 15% supported removing or eradicating macaques. 87.6% felt that it is importance to conserve and protect macaques. Our results show that human-macaque conflict exists in Singapore, but that it may not be severe. Human behavior is largely responsible for macaque-to-human interactions, and thus could be lessened with management of human behavior in interface zones (i.e. restrict food carrying and provocation). Moreover, our interviews shows people living in Singapore value macaques, do not wish them entirely removed, prefer education-based solutions, and consider conservation and protection of them important.

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.

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.