Mortality in captive baboons (Papio spp.): a-23-year study

Gastrointestinal tract pathology of the owl monkey (Aotus spp.)

Owl monkeys are small nocturnal new world primates in the genus Aotus that are most used in biomedical research for malaria. Cardiomyopathy and nephropathy are well-described common diseases contributing to their morbidity and mortality; less is known about lesions affecting the gastrointestinal tract. Records from a 14-year period (2008-2022) at the Keeling Center for Comparative Medicine and Research were queried to identify instances of spontaneous gastrointestinal disease that directly contributed to the cause of death from the 235 adult owl monkeys submitted for necropsy. Of the 235, 10.6% (25/235) had gastrointestinal disease listed as a significant factor that contributed to morbidity and mortality. Diagnoses included candidiasis (3/25), gastric bloat (4/25), and intestinal incarceration and ischemia secondary (11/25), which included intussusception (4/25), mesenteric rent (3/25), strangulating lipoma (2/25), intestinal torsion (1/25), and an inguinal hernia (1/25). Intestinal adenocarcinomas affecting the jejunum (4/25) were the most common neoplasia diagnosis. Oral squamous cell carcinoma (1/25) and intestinal lymphoma (2/25) were also diagnosed. This report provides evidence of spontaneous lesions in the species that contribute to morbidity and mortality.

Impact of human created environments in the pathogenic potential and antimicrobial resistance of staphylococci from wild neotropical primates in Brazil

The non-human primate (NHP) Leontopithecus rosalia is an endangered species native of Brazil and lives in forest fragments with different levels of contact with humans (natural, private and urban). Other NHPs - Callithrix spp. - were introduced by humans and co-exist and interact with the native species in these forests. To evaluate if living in or close to human-modified environments could constitute a risk for L. rosalia, we compared the prevalence, genetic background, antibiotic susceptibility and virulence gene content of staphylococci collected from the native and the introduced species from different forest fragments. We found that presence in human-dominated environments increased the colonization rate of L. rosalia with Mammaliicoccus sciuri (former Staphylococcus sciuri) from 18 % to 85 % (p = 0.0001) and of Callithrix spp with Staphylococcus aureus from 6 % to 100 % (p = 0.0001). According to molecular typing data obtained differences probably resulted from dissemination of these bacterial species from the invader NHP species and from humans. Changes in microbiota were paralleled by an increase in the prevalence of Panton-Valentine Leukocidin gene and in resistance to beta-lactams, macrolides and/or lincosamides as exposure to human environment increased. In particular, erythromycin resistance in S. aureus from Callithrix spp. increased from 0 % to 50 % and resistance rate to at least one antibiotic in coagulase-negative staphylococci species from L. rosalia increased from 13 % to 56 % (p = 0.0003). Our results showed that contact of native animal species with human-created environments increased the content of antimicrobial resistant and pathogenic bacteria on their commensal microbiota, which ultimately can impact on their health. IMPORTANCE: Endangered animal species are vulnerable to environmental alterations and human activities have been repeatedly identified as factors driving drastic changes in the natural landscape. It is extremely important to monitor changes in the environment surrounding protected species, because this could lead to early detection of any potential threats. In this study, we found that the contact of L. rosalia - a protected non-human primate from Brazil - with human environments is related to changes in their commensal microbiota. These included an increase in the number of pathogenic and antibiotic resistant bacteria, which have a higher potential to cause infections that are more difficult to treat. We provided evidence for the harmful impact human contact has on L. rosalia. Also, our results suggest that monitoring of commensal microbiota of protected animal species might be a useful way of sensing the risks of protected species to human exposure.

Sarcina sp. as a presumptive cause of fatal acute gastric dilation and gastric emphysema in rhesus macaques

A 4-y-old female and 3-y-old male rhesus macaque (Macaca mulatta), both housed in the same facility, died unexpectedly within 2 wk. Postmortem examination revealed severe gastric dilation in both macaques and gastric emphysema in the female macaque. Histologically, bacteria consistent with Sarcina sp. were present in both macaques within the lungs and lumen of the trachea, esophagus, and gastrointestinal (GI) tract without associated inflammation. Additionally, in the female macaque, the bacteria were found in the gastric mucosa and associated with emphysematous spaces in the gastric wall without associated inflammation. PCR and Sanger sequencing of amplicons were subsequently performed on GI contents and non-alimentary tissues from the 2 affected monkeys and on comparative samples from unaffected rhesus monkeys in the same facility and an adjacent primate facility. The cases were compared using the 2-tailed Fisher exact test (p-value at 95% confidence). PCR identified Sarcina in GI contents of both affected and unaffected monkeys (p = 0.6084) and in non-alimentary tissues of affected monkeys only (p = 0.0083). These results suggest that the presence of Sarcina sp. in non-alimentary tissues is associated with gastric distension, gas accumulation, and unexpected death in nonhuman primates.

A Literature Review of Unintentional Intoxications of Nonhuman Primates

Simple Summary

This report is an overview of the published veterinary literature on unintentional poisonings in wild and captive nonhuman primates (NHP). Selected intoxications will be described with emphasis on the clinical signs, laboratory, and main postmortem findings as well as the available treatment options. Mostly, NHP died suddenly and unexpectedly without showing any preceding clinical signs. The (presumptive) diagnosis of a poisoning was mostly made postmortem by laboratory testing of post-mortem fluid, tissue samples, and stomach contents. From these reports, we concluded that the toxic threats to wild NHP are different to those of captive NHP because of the environment in which they live. We also concluded that a poisoning or an intoxication should be part of a differential diagnosis when a NHP presents with clinical signs that cannot be linked to a known disorder or dies suddenly with no preceding clinical signs.

Abstract

Reports of unintentional intoxications in nonhuman primates (NHP) are few and an up-to-date review of such intoxications in NHP is lacking. We reviewed the published veterinary literature on unintentional intoxications in wild and captive NHP in order to provide a useful resource on known toxic agents of NHP for veterinarians, caregivers, and researchers who work with NHP. To these ends, we first conducted a literature search for books, book chapters, peer-reviewed publications, conference proceedings, and newsletters in academic literature databases such as Google Scholar, PubMed, BioOne Complete, and Web of Science using the words and word combinations such as heavy metals, pesticides, poisonings, and nonhuman primates. We then evaluated the search results for those reports that we considered as clinically relevant and then classified them according to the toxic agent. We identified lead, zinc, phytotoxins, pesticides, botulinum toxin, polychlorinated biphenyls, and snake and spider venoms as the main toxic agents in wild and captive NHP. We concluded that the toxic threats to wild NHP are different to those of captive NHP because of the environment in which they live. We recommend that an intoxication should be part of a differential diagnosis when a NHP presents with clinical signs that cannot be linked to a known disorder or dies suddenly with no preceding clinical signs. In cases of the former, laboratory testing for known toxins and pollutants should be conducted. In cases of the latter, a thorough postmortem examination, together with extensive laboratory testing, for known toxins and environmental pollutants in all tissues and organs should be performed.

Causes of death in neotropical primates in Rio Grande do Sul State, Southern Brazil

BACKGROUND

Anthropogenic disturbances are the main threats to nonhuman primates conservation, and infectious diseases may also play a key role in primate population decline. This study aimed to determine the main causes of death in neotropical primates.

METHODS

A retrospective study of post-mortem examinations was conducted on 146 neotropical primates between January 2000 and December 2018.

RESULTS

Conclusive diagnoses were obtained in 68.5% of the cases, of which 59 corresponded to non-infectious causes and 41 to infectious diseases. Trauma was the main cause of death (54/100), with anthropogenic stressors caused by blunt force trauma injuries (collision with vehicles) and puncture wound injuries associated with interspecific aggression (dog predation) were the most common factors. Other causes of death included bacterial diseases (27%), followed by parasitic diseases (12%), neoplasms (2%), and viral diseases (2%).

CONCLUSIONS

Free-ranging primates were mostly affected by non-infectious causes, while captive primates were by infectious conditions.

Research Relevant Conditions and Pathology in Nonhuman Primates

Biomedical research involving animal models continues to provide important insights into disease pathogenesis and treatment of diseases that impact human health. In particular, nonhuman primates (NHPs) have been used extensively in translational research due to their phylogenetic proximity to humans and similarities to disease pathogenesis and treatment responses as assessed in clinical trials. Microscopic changes in tissues remain a significant endpoint in studies involving these models. Spontaneous, expected (ie, incidental or background) histopathologic changes are commonly encountered and influenced by species, genetic variations, age, and geographical origin of animals, including exposure to infectious or parasitic agents. Often, the background findings confound study-related changes, because numbers of NHPs used in research are limited by animal welfare and other considerations. Moreover, background findings in NHPs can be exacerbated by experimental conditions such as treatment with xenobiotics (eg, infectious morphological changes related to immunosuppressive therapy). This review and summary of research-relevant conditions and pathology in rhesus and cynomolgus macaques, baboons, African green monkeys, common marmosets, tamarins, and squirrel and owl monkeys aims to improve the interpretation and validity of NHP studies.

Local immune responses to tuberculin skin challenge in Mycobacterium bovis BCG-vaccinated baboons: a pilot study of younger and older animals

Individuals over the age of 65 are highly susceptible to infectious diseases, which account for one-third of deaths in this age group. Vaccines are a primary tool to combat infection, yet they are less effective in the elderly population. While many groups have aimed to address this problem by studying vaccine-induced peripheral blood responses in the elderly, work from our lab and others demonstrate that immune responses to vaccination and infectious challenge may differ between tissue sites and the periphery. In this pilot study, we established an in vivo delayed-type hypersensitivity model of Mycobacterium bovis BCG vaccination and tuberculin skin test in two adult and two aged baboons. Vaccination generates BCG-specific immune cells that are recruited to the skin upon tuberculin challenge. We tested short term recall responses (8 weeks post-vaccination) and long term recall responses (25 weeks post-vaccination) by performing skin punch biopsies around the site of tuberculin injection. In short term recall responses, we found increased oxidation and decreased production of immune proteins in aged baboon skin at the site of TST challenge, in comparison to adult skin. Differences between adult and aged animals normalized in the long term response to tuberculin. In vitro, aged peripheral blood mononuclear cells had increased migration and functional responses to antigen-specific stimulation, suggesting that age-related changes in the tissue in vivo impairs aged immune recall responses to antigenic challenge. These findings highlight the impact of age-associated changes in the local tissue environment in memory recall responses, which may be more broadly applied to the study of other tissues. Moreover, these findings should be considered in future studies aimed at understanding and improving aging immune responses to vaccination and tissue challenge.

Hair cortisol in captive corral-housed baboons

Hair cortisol concentrations (HCCs) are measures of long-term hypothalamic-pituitary-adrenocortical (HPA) activity and can be used as indicators of chronic stress. However, intrinsic factors such as an animal's age and sex can also have an impact on resulting HCCs. Although baboons are commonly studied in captivity, little is known about baseline HCC in this population. Here we measured HCC in two same-sex groups of captive olive (Papio hamadryas anubis) baboons and olive/yellow baboon (Papio hamadryas cynocephalus) crosses housed in large outdoor corrals, and we assessed the impact of age and sex on HCC as major variables of interest. Hair was gently shaved from the back of the neck when the animals were sedated for routine physicals. Subjects were divided into three age categories: juvenile (2-4 years), adult (9-12 years), and senior (13-19 years). The "senior" category contained only males. Results confirm an effect of sex and age on HCCs. Females had higher levels of hair cortisol than males, and juveniles had higher levels than adults. There was also a significant sex × age interaction. There were no sex differences in HCCs in juveniles, but there was a greater decline in HCCs in adult males than in adult females. Within males, there was a significant difference in levels of hair cortisol across the three age categories. Juveniles had higher levels than did adults and seniors, but adults and seniors were not significantly different from one another. These results provide baseline measures of hair cortisol in captive baboons and demonstrate effects of sex and age on HCCs.

Pathology Associated With Streptococcus spp. Infection in Baboons (Papio spp.)

Streptococcus spp. are a source of morbidity and mortality in captive nonhuman primate populations. However, little is known about the lesions associated with naturally occurring streptococcal infections in baboons (Papio spp.). The pathology database of the Southwest National Primate Research Center was searched for all baboon autopsies from 1988 to 2018 in which Streptococcus spp. were cultured. Baboons on experimental protocol were excluded. The gross autopsy and histopathology reports were reviewed. Archived specimens were retrieved and reviewed as needed for confirmation or clarification. Fifty-six cultures were positive for Streptococcus spp. in 54 baboons with evidence of bacterial infection. Associated gross lesions included purulent exudate, fibrinous to fibrous adhesions, hemorrhage, mucosal thickening, organomegaly, and abscessation. Histologic lesions included suppurative inflammation, abscessation, necrosis, hemorrhage, fibrin accumulation, and thrombosis. Lungs and pleura (n = 31) were the most commonly infected organ followed by the central nervous system (n = 16), spleen (n = 15), soft tissues (n = 12), air sacs, liver, peritoneum, adrenal glands, heart, lymph nodes, uterus, kidneys, biliary system, bones, ears, umbilical structures, mammary glands, pancreas, placenta, and salivary glands. Infections by non-β-hemolytic Streptococcus spp. predominated in the lungs and air sacs; the most common isolate was Streptococcus pneumoniae. Infections by β-hemolytic Streptococcus spp. predominated in the soft tissues and reproductive tract. Naturally occurring β-hemolytic and non-β-hemolytic Streptococcus spp. infections cause morbidity and mortality in captive baboon populations. The lesions associated with streptococcal infection are similar to those reported in human infection. Thus, the baboon may represent an underutilized model for studying Streptococcus spp. as pathogens.

Gingival histoplasmosis: An atypical presentation of African histoplasmosis in three baboons (Papio spp)

Gingival lesions as the sole manifestation of African histoplasmosis (Histoplasma capsulatum var. duboisii) have never been reported in baboons. Grossly, lesions can be indistinguishable from bacterial ulcerative gingivitis or gingival hyperplasia. Clinical outcomes of primary gingival histoplasmosis in baboons are unknown and may complicate colony management decisions.

MORTALITY IN COQUEREL'S SIFAKAS ( PROPITHECUS COQUERELI) UNDER HUMAN CARE: A RETROSPECTIVE SURVEY FROM THE DUKE LEMUR CENTER 1990-2015

  Coquerel's sifakas ( Propithecus coquereli) are diurnal, folivorous lemurs native to Madagascar and one of only two members of the genus Propithecus currently housed in human care settings outside of Madagascar. This species has a lifespan of approximately 30 yr but minimal information exists regarding morbidity and mortality in human care settings. In this retrospective study, medical records, postmortem exam, and autopsy reports from 56 animals housed at the Duke Lemur Center from 1990 to 2015 were evaluated. Mortality assessments included age, sex, time of year, histopathological findings, major organ system impacted, and etiological factors. Mortality was most prevalent among adults greater than 2 yr of age (42.9%) and neonates less than 7 days of age (30.4%). The top four morphological diagnoses accounted for 51.7% of all deaths and included stillbirths (19.6%), enteritis-colitis (12.5%), failure to thrive (10.7%), and systemic protozoal infections (8.9%). The two most commonly affected organ systems in animals over 7 days of age were multisystem disease (30.8%) and the gastrointestinal system (28.2%). Infections were the most common etiology with bacterial being the most prevalent followed by protozoal infections. The results provide insight into common causes of mortality of this species and can be used to guide management of this endangered primate and improve longevity in human care settings.

Salivary gland neoplasms in non-human primates: A case series and brief literature review

BACKGROUND

Salivary gland neoplasms are rare in non-human primates.

METHODS

Thirty-five years of pathology records were reviewed at the Southwest (SNPRC) and Yerkes (YNPRC) National Primate Research Centers. An in-depth literature search for salivary gland neoplasms in non-human primates was performed.

RESULTS

Seventeen salivary gland neoplasms (nine from SNPRC and YNPRC, eight from published literature) were identified. There were seven malignant, nine benign, and one of undetermined behavior identified in eight rhesus macaques, six baboons, a chimpanzee, a bonnet macaque, and a moustached tamarin. Parotid gland was the most frequent origin (n = 7), followed by mandibular (n = 4) or minor salivary glands (n = 2). Two animals with salivary gland adenoma had a history of prior radiation exposure.

CONCLUSIONS

Parotid glands are the most common origin for salivary gland neoplasms. Salivary gland neoplasms should be considered in the differential diagnoses of head and neck masses in non-human primates.

Duodenal adipose tissue is associated with obesity in baboons (Papio sp): a novel site of ectopic fat deposition in non-human primates

AIMS

Ectopic fat is a recognized contributor to insulin resistance and metabolic dysfunction, while the role of fat deposition inside intestinal wall tissue remains understudied. We undertook this study to directly quantify and localize intramural fat deposition in duodenal tissue and determine its association with adiposity.

METHODS

Duodenal tissues were collected from aged (21.2 ± 1.3 years, 19.5 ± 3.1 kg, n = 39) female baboons (Papio sp.). Fasted blood was collected for metabolic profiling and abdominal circumference (AC) measurements were taken. Primary tissue samples were collected at the major duodenal papilla at necropsy: one full cross section was processed for hematoxylin and eosin staining and evaluated; a second full cross section was processed for direct chemical lipid analysis on which percentage duodenal fat content was calculated.

RESULTS

Duodenal fat content obtained by direct tissue quantification showed considerable variability (11.95 ± 6.93%) and was correlated with AC (r = 0.60, p < 0.001), weight (r = 0.38, p = 0.02), leptin (r = 0.63, p < 0.001), adiponectin (r = - 0.32, p < 0.05), and triglyceride (r = 0.41, p = 0.01). The relationship between duodenal fat content and leptin remained after adjusting for body weight and abdominal circumference. Intramural adipocytes were found in duodenal sections from all animals and were localized to the submucosa. Consistent with the variation in tissue fat content, the submucosal adipocytes were non-uniformly distributed in clusters of varying size. Duodenal adipocytes were larger in obese vs. lean animals (106.9 vs. 66.7 µm², p = 0.02).

CONCLUSIONS

Fat accumulation inside the duodenal wall is strongly associated with adiposity and adiposity related circulating biomarkers in baboons. Duodenal tissue fat represents a novel and potentially metabolically active site of ectopic fat deposition.

Mismatch repair gene mutations lead to lynch syndrome colorectal cancer in rhesus macaques

Colorectal cancer accounts for a substantial number of deaths each year worldwide. Lynch Syndrome is a genetic form of colorectal cancer (CRC) caused by inherited mutations in DNA mismatch repair (MMR) genes. Although researchers have developed mouse models of Lynch Syndrome through targeted mutagenesis of MMR genes, the tumors that result differ in important ways from those in Lynch Syndrome patients. We identified 60 cases of CRC in rhesus macaques (Macaca mulatta) at our facility since 2001. The tumors occur at the ileocecal junction, cecum and proximal colon and display clinicopathologic features similar to human Lynch Syndrome. We conducted immunohistochemical analysis of CRC tumors from several rhesus macaques, finding they frequently lack expression of MLH1 and PMS2 proteins, both critical MMR proteins involved in Lynch Syndrome. We also found that most macaque cases we tested exhibit microsatellite instability, a defining feature of Lynch Syndrome. Whole genome sequencing of rhesus macaque CRC cases identified mutations in MLH1 and/or MSH6 that are predicted to disrupt protein function. We conclude that this population of rhesus macaques constitutes a spontaneous model of Lynch Syndrome, matching the human disease in several significant characteristics, including genetic risk factors that parallel human Lynch Syndrome.

Vaginal Dysbiosis from an Evolutionary Perspective

Evolutionary approaches are powerful tools for understanding human disorders. The composition of vaginal microbiome is important for reproductive success and has not yet been characterized in the contexts of social structure and vaginal pathology in non-human primates (NHPs). We investigated vaginal size, vulvovaginal pathology and the presence of the main human subtypes of Lactobacillus spp./ BV-related species in the vaginal microflora of baboons (Papio spp.). We performed morphometric measurements of external and internal genitalia (group I, n = 47), analyzed pathology records of animals from 1999–2015 (group II, n = 64 from a total of 12,776), and evaluated vaginal swabs using polymerase chain reaction (PCR) (group III, n = 14). A total of 68 lesions were identified in 64 baboons. Lactobacillus iners, Gardnerella vaginalis, Atopobium vaginae, Megasphaera I, and Megasphaera II were not detected. L. jensenii, L. crispatus, and L. gasseri were detected in 2/14 (14.2%), 1/14 (7.1%), and 1/14 (7.1%) samples, respectively. BVAB2 was detected in 5/14 (35.7%) samples. The differences in the vaginal milieu between NHP and humans might be the factor associated with human-specific pattern of placental development and should be taken in consideration in NHP models of human pharmacology and microbiology.

Cellular Immune Responses against Simian T-Lymphotropic Virus Type 1 Target Tax in Infected Baboons

There are currently 5 million to 10 million human T-lymphotropic virus type 1 (HTLV-1)-infected people, and many of them will develop severe complications resulting from this infection. A vaccine is urgently needed in areas where HTLV-1 is endemic. Many vaccines are best tested in nonhuman primate animal models. As a first step in designing an effective HTLV-1 vaccine, we defined the CD8(+) and CD4(+) T cell response against simian T-lymphotropic virus type 1 (STLV-1), a virus closely related to HTLV-1, in olive baboons (Papio anubis). Consistent with persistent antigenic exposure, we observed that STLV-1-specific CD8(+) T cells displayed an effector memory phenotype and usually expressed CD107a, gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α). To assess the viral targets of the cellular immune response in STLV-1-infected animals, we used intracellular cytokine staining to detect responses against overlapping peptides covering the entire STLV-1 proteome. Our results show that, similarly to humans, the baboon CD8(+) T cell response narrowly targeted the Tax protein. Our findings suggest that the STLV-1-infected baboon model may recapitulate some of the important aspects of the human response against HTLV-1 and could be an important tool for the development of immune-based therapy and prophylaxis.

IMPORTANCE

HTLV-1 infection can lead to many different and often fatal conditions. A vaccine deployed in areas of high prevalence might reduce the incidence of HTLV-1-induced disease. Unfortunately, there are very few animal models of HTLV-1 infection useful for testing vaccine approaches. Here we describe cellular immune responses in baboons against a closely related virus, STLV-1. We show for the first time that the immune response against STLV-1 in naturally infected baboons is largely directed against the Tax protein. Similar findings in humans and the sequence similarity between the human and baboon viruses suggest that the STLV-1-infected baboon model might be useful for developing a vaccine against HTLV-1.

The baboon (Papio sp.) as a model for female reproduction studies

BIOLOGY AND REPRODUCTION

Due to their size and anatomical similarity to humans, baboons make an excellent model for reproductive studies. Baboons have a simple short cervix, muscular uterus, ovaries just lateral to the uterus and similar vasculature to that of humans. Because of the size of the animals, instruments designed for use in women can be readily used on baboons. Noninvasive determination of phase of estrous cycle is readily made by observation of changes in perineal sexual skin turgor and color.

ADVANTAGES

Some advantages of use of baboons compared to other nonhuman primates is that they are nonseasonal breeders allowing for studies to be conducted year round, have minimal infectious disease risks to humans as they do not carry Herpes B and have a social structure allowing for easy group formation. Baboons serve as good models for many conditions in humans and should be considered for studies investigating reproductive issues.

Osteosarcoma in Baboons (Papio spp)

Bone neoplasms in baboons (Papio spp) are rare, with only one confirmed case of osteosarcoma previously described in the literature. Over a 12-y period, 6 baboons at a national primate research center presented with naturally occurring osteosarcoma; 3 lesions affected the appendicular skeleton, and the remaining 3 were in the head (skull and mandible). The 6 cases presented were identified in members of a large outdoor-housed breeding colony. The subjects were not genetically related or exposed to the same research conditions. Diagnoses were made based on the presentation and radiographic findings, with histologic confirmation.