Search

The endangered mountain gorilla (Gorilla beringei beringei) in Rwanda, Uganda, and the Democratic Republic of Congo is frequently in contact with humans through tourism, research activities, and illegal entry of people into protected gorilla habitat. Herpesviruses, which are ubiquitous in primates, have the potential to be shared in any setting where humans and gorillas share habitat. Based on serological findings and clinical observations of orofacial ulcerated lesions resembling herpetic lesions, an alpha‐herpesvirus resembling human herpes simplex virus type 1 (HSV‐1) has long been suspected to be present in human‐habituated mountain gorillas in the wild. While the etiology of orofacial lesions in the wild has not been confirmed, HSV‐1 has been suspected in captively‐housed mountain gorillas and confirmed in a co‐housed confiscated Grauer's gorilla (Gorilla beringei graueri). To better characterize herpesviruses infecting mountain gorillas and to determine the presence/absence of HSV‐1 in the free‐living population, we conducted a population‐wide survey to test for the presence of orally shed herpesviruses. DNA was extracted from discarded chewed plants collected from 294 individuals from 26 groups, and samples were screened by polymerase chain reaction using pan‐herpesvirus and HSV‐1‐specific assays. We found no evidence that human herpesviruses had infected free‐ranging mountain gorillas. However, we found gorilla‐specific homologs to human herpesviruses, including cytomegaloviruses (GbbCMV‐1 and 2), a lymphocryptovirus (GbbLCV‐1), and a new rhadinovirus (GbbRHV‐1) with similar characteristics (i.e., timing of primary infection, shedding in multiple age groups, and potential modes of transmission) to their human counterparts, human cytomegalovirus, Epstein‐Barr virus and Kaposi's sarcoma‐associated herpesvirus, respectively. Research highlights: Discovery of mountain gorilla‐specific homologs to human herpesviruses, including cytomegaloviruses, a lymphocryptovirus, and a rhadinovirus with similar characteristics to their human counterparts.Human herpes simplex virus type 1 (HSV‐1) has not entered the wild mountain gorilla population despite frequent contact with humans.Any potential future consideration of reintroduction of captive mountain gorillas should carefully consider the possibiliy of introducing HSV‐1 and other human pathogens to the wild population. [ABSTRACT FROM AUTHOR]

The finding of parasites and bacterial pathogens in mountain gorilla feces and oral lesions in gorilla skeletal remains has not been linked to pathological evidence of morbidity or mortality. In the current study, we conducted a retrospective study of digestive tracts including oral cavity, salivary glands, esophagus, stomach, intestines (gastrointestinal tract [GI]), liver, and pancreas of 60 free‐ranging mountain gorillas from Uganda, Rwanda, and the Democratic Republic of Congo that died between 1985 and 2007. We reviewed clinical histories and gross pathology reports and examined histological sections. On histology, enteritis (58.6%), gastritis (37.3%), and colitis (29.3%) were the commonest lesions in the tracts. Enteritis and colitis were generally mild, and judged likely to have been subclinical. Gastritis was often chronic and proliferative or ulcerative, and associated with nematodiasis. A gastro‐duodenal malignancy (carcinoid) was present in one animal. A number of incidental lesions were identified throughout the tract and cestodes and nematodes were frequently observed grossly and/or histologically. Pigmentation of teeth and tongue were a common finding, but periodontitis and dental attrition were less common than reported from past studies of skeletal remains. Despite observing numerous GI lesions and parasites in this study of deceased free‐living mountain gorillas, we confirmed mortality attributable to gastroenteritis in just 8% (5/60) cases, which is less than that described in captive gorillas. Other deaths attributed to digestive tract lesions included cleft palate in an infant, periodontal disease causing systemic infection in an older adult and gastric cancer. Of all the parasitic infections observed, only hepatic capillariasis and gastric nematodiasis were significantly associated with lesions (hepatitis and gastritis, respectively). Understanding GI lesions in this endangered species is key in the management of morbidity associated with GI ailments. Research Highlights: Oral lesions were less than in previous skeletal studies.Nematodiasis and capillariasis were risks to gastritis and hepatitis, respectively. Cestodes reduced the risk for enteritis.Mortality due to gastrointestinal tract lesions was less than that in captive gorillas. [ABSTRACT FROM AUTHOR]

The genetic relatedness of mountain gorillas and humans has led to concerns about interspecies transmission of infectious agents. Human-to-gorilla transmission may explain human metapneumovirus in 2 wild mountain gorillas that died during a respiratory disease outbreak in Rwanda in 2009. Surveillance is needed to ensure survival of these critically endangered animals. [ABSTRACT FROM AUTHOR]

Mountain gorillas ( Gorilla beringei beringei) are one of the most critically endangered great apes in the world. The most common cause of mountain gorilla morbidity and mortality is trauma (e.g., injury from conspecifics or snare entrapment). We conducted a retrospective case-control study of free-ranging, human-habituated mountain gorillas to evaluate factors associated with snare entrapment and the results of clinical intervention. Data were collected from clinical records on all clinical intervention cases ( n=132) in Volcanoes National Park, Rwanda, conducted between 1995-2015. Wildlife veterinarians treated 37 gorillas entrapped in snares and 95 gorillas for other clinical conditions (including trauma and respiratory illness). Multivariate statistical analyses revealed that young gorillas (<8 yr old) were more likely than older gorillas to become snared; that comorbidities delayed times to intervention (≥3 d); and that severity of wounds at the time of intervention were associated with increased risk of lasting impairment (including loss of limb or limb function, or death) within 1 mo after intervention. Our results may influence decisions for gorilla health monitoring and treatment to most effectively conserve this critically endangered species.

Objectives: Ecological factors, but also tooth-to-tooth contact over time, have a dramatic effect on tooth wear in primates. The aim of this study is to test whether incisor tooth wear changes predictably with age and can thus be used as an age estimation method in a wild population of mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park, Rwanda., Materials and Methods: In mountain gorillas of confidently known chronological age (N = 24), we measured the crown height of all permanent maxillary and mandibular incisors (I 1 , I 1 , I 2 , I 2 ) as a proxy for incisal macrowear. Linear and quadratic regressions for each incisor were used to test whether age can be predicted by crown height. Using these models, we then predicted age at death of two individual mountain gorillas of probable identifications, based on their incisor crown height., Results: Age decreased significantly with incisor height for all teeth, but the upper first incisors (I 1 ) provided the best results, with the lowest Akaike's Information Criterion corrected for small sample size (AICc) and lowest Standard Error of the Estimate (SEE). When the best age equations for each sex were applied to gorillas with probable identifications, the predicted ages differed 1.58 and 3.33 years from the probable ages of these individuals., Conclusions: Our findings corroborate that incisor crown height, a proxy for incisal wear, varies predictably with age. This relationship can be used to estimate age at death of unknown gorillas in the skeletal collection, and in some cases, to corroborate the identity of individual gorillas recovered from the forest postmortem at an advanced state of decomposition. Such identifications help fill gaps in the demographic database and support research that requires individual-level data., (© 2018 Wiley Periodicals, Inc.)

Mountain gorillas are an endangered great ape subspecies and a prominent focus for conservation, yet we know little about their genomic diversity and evolutionary past. We sequenced whole genomes from multiple wild individuals and compared the genomes of all four Gorilla subspecies. We found that the two eastern subspecies have experienced a prolonged population decline over the past 100,000 years, resulting in very low genetic diversity and an increased overall burden of deleterious variation. A further recent decline in the mountain gorilla population has led to extensive inbreeding, such that individuals are typically homozygous at 34% of their sequence, leading to the purging of severely deleterious recessive mutations from the population. We discuss the causes of their decline and the consequences for their future survival., (Copyright © 2015, American Association for the Advancement of Science.)

Background: Infectious diseases represent the greatest threats to endangered species, and transmission from humans to wildlife under increased anthropogenic pressure has been always stated as a major risk of habituation., Aims: To evaluate the impact of close contact with humans on the occurrence of potentially zoonotic protists in great apes, one hundred mountain gorillas (Gorilla beringei beringei) from seven groups habituated either for tourism or for research in Volcanoes National Park, Rwanda were screened for the presence of microsporidia, Cryptosporidium spp. and Giardia spp. using molecular diagnostics., Results: The most frequently detected parasites were Enterocytozoon bieneusi found in 18 samples (including genotype EbpA, D, C, gorilla 2 and five novel genotypes gorilla 4-8) and Encephalitozoon cuniculi with genotype II being more prevalent (10 cases) compared to genotype I (1 case). Cryptosporidium muris (2 cases) and C. meleagridis (2 cases) were documented in great apes for the first time. Cryptosporidium sp. infections were identified only in research groups and occurrence of E. cuniculi in research groups was significantly higher in comparison to tourist groups. No difference in prevalence of E. bieneusi was observed between research and tourist groups., Conclusion: Although our data showed the presence and diversity of important opportunistic protists in Volcanoes gorillas, the source and the routes of the circulation remain unknown. Repeated individual sampling, broad sampling of other hosts sharing the habitat with gorillas and quantification of studied protists would be necessary to acquire more complex data.

Mountain gorillas (Gorilla beringei beringei) are critically endangered primates surviving in two isolated populations in protected areas within the Virunga Massif of Rwanda, Uganda, the Democratic Republic of Congo, and in Bwindi Impenetrable National Park in Uganda. Mountain gorillas face intense ecologic pressures due to their proximity to humans. Human communities outside the national parks, and numerous human activities within the national parks (including research, tourism, illegal hunting, and anti-poaching patrols), lead to a high degree of contact between mountain gorillas and wildlife, domestic animals, and humans. To assess the pathogen transmission potential between wildlife and livestock, feces of mountain gorillas, forest buffalo (Syncerus caffer nanus), and domestic cattle (Bos taurus) in Rwanda were examined for the parasites Giardia and Cryptosporidium. Giardia was found in 9% of mountain gorillas, 6% of cattle, and 2% of forest buffalo. Our study represents the first report of Giardia prevalence in forest buffalo. Cryptosporidium-like particles were also observed in all three species. Molecular characterization of Giardia isolates identified zoonotic genotype assemblage B in the gorilla samples and assemblage E in the cattle samples. Significant spatial clustering of Giardia-positive samples was observed in one sector of the park. Although we did not find evidence for transmission of protozoa from forest buffalo to mountain gorillas, the genotypes of Giardia samples isolated from gorillas have been reported in humans, suggesting that the importance of humans in this ecosystem should be more closely evaluated.

Between 1990 and 2010, 18 outbreaks of respiratory disease occurred in Rwanda's wild human-habituated mountain gorillas (Gorilla beringei beringei). An outbreak was defined as clinically observable respiratory illness involving at least one third of all the gorillas in a family group (> 30% morbidity) over the course of at least 7 days. Outbreaks lasted 2 wk to 4 mo and affected up to five different gorilla family groups, either concurrently or sequentially. An outbreak was considered over if no further clinical illness was observed in the same or another group for at least 1 mo. Clinical signs varied from nasal discharge, sneezing, and mild intermittent coughing (mild), to spasmodic coughing, lethargy, and partial anorexia (moderate), to dyspnea, tachypnea, respiratory distress, weakness, complete anorexia, and occasionally death (severe). Nearly every mountain gorilla group habituated for tourism or research in Rwanda experienced at least one outbreak, and they may be increasing in frequency. In the first 15 yr of the review period 1990-2005, there were nine outbreaks involving 16 gorilla groups; in the last 5 yr of the review period, 2006-2010, there were nine outbreaks involving 11 groups. Although most gorillas recovered without treatment, 41 veterinary procedures were required to medically manage 35 severely ill individuals. Given the rise of mountain gorilla ecotourism in Rwanda, the possibility that respiratory disease results from contact with infected humans is of great concern, and both the etiology and epidemiology of this problem are active areas of research. The observed clinical signs, response to antimicrobial therapy among the sickest individuals, and postmortem findings are most consistent with viral upper respiratory tract infections complicated in some cases by secondary bacterial infections. The current gorilla visitation rules have been designed to minimize the risk of disease transmission between humans and wild human-habituated great apes.

Cysts morphologically resembling Balantidium coli were identified in the feces of a mountain gorilla (Gorilla beringei beringei). Confirmatory PCR and sequencing revealed two distinct B. coli-specific sequences (ITS-1, sub-types A0 and B1). This represents the first report of B. coli in this species, raising the possibility of infection from a reservoir host.

Understanding the life history correlates of ontogenetic differences in hominoid brain growth requires information from multiple species. At present, however, data on how brain size changes over the course of development are only available from chimpanzees and modern humans. In this study, we examined brain growth in wild Virunga mountain gorillas using data derived from necropsy reports (N = 34) and endocranial volume (EV) measurements (N = 86). The youngest individual in our sample was a 10-day-old neonatal male with a brain mass of 208 g, representing 42% of the adult male average. Our results demonstrate that Virunga mountain gorillas reach maximum adult-like brain mass by 3-4 years of age; adult-sized EV is reached by the time the first permanent molars emerge. This is in contrast to the pattern observed in chimpanzees, which despite their smaller absolute brain size, reportedly attain adult brain mass approximately 1 year later than Virunga mountain gorillas. Our findings demonstrate that brain growth is completed early in Virunga mountain gorillas compared to other great apes studied thus far, in a manner that appears to be linked with other life history characteristics of this population., (© 2012 Wiley Periodicals, Inc.)