Population structure, intergroup interaction, and human contact govern infectious disease impacts in mountain gorilla populations.

Infectious zoonotic diseases are a threat to wildlife conservation and global health. They are especially a concern for wild apes, which are vulnerable to many human infectious diseases. As ecotourism, deforestation, and great ape field research increase, the threat of human-sourced infections to wild populations becomes more substantial and could result in devastating population declines. The endangered mountain gorillas (Gorilla beringei beringei) of the Virunga Massif in east-central Africa suffer periodic disease outbreaks and are exposed to infections from human-sourced pathogens. It is important to understand the possible risks of disease introduction and spread in this population and how human contact may facilitate disease transmission. Here we present and evaluate an individual-based, stochastic, discrete-time disease transmission model to predict epidemic outcomes and better understand health risks to the Virunga mountain gorilla population. To model disease transmission we have derived estimates for gorilla contact, interaction, and migration rates. The model shows that the social structure of gorilla populations plays a profound role in governing disease impacts with subdivided populations experiencing less than 25% of the outbreak levels of a single homogeneous population. It predicts that gorilla group dispersal and limited group interactions are strong factors in preventing widespread population-level outbreaks of infectious disease after such diseases have been introduced into the population. However, even a moderate amount of human contact increases disease spread and can lead to population-level outbreaks.

Cutaneous Filariasis in Free-Ranging Rothschild's Giraffes (Giraffa camelopardalis rothschildi) in Uganda.

Across Africa, wild giraffes suffer from a variety of skin disorders of mostly unknown etiology. With their populations already threatened from anthropogenic factors, it is important to understand infectious disease risks to giraffes. Here we describe filarid parasites and a portion of their genetic sequence associated with skin disease in Rothschild's giraffes (Giraffa camelopardalis rothschildi) in Uganda.

Effect of Antibiotic Treatment on the Gastrointestinal Microbiome of Free-Ranging Western Lowland Gorillas (Gorilla g. gorilla).

The mammalian gastrointestinal (GI) microbiome, which plays indispensable roles in host nutrition and health, is affected by numerous intrinsic and extrinsic factors. Among them, antibiotic (ATB) treatment is reported to have a significant effect on GI microbiome composition in humans and other animals. However, the impact of ATBs on the GI microbiome of free-ranging or even captive great apes remains poorly characterized. Here, we investigated the effect of cephalosporin treatment (delivered by intramuscular dart injection during a serious respiratory outbreak) on the GI microbiome of a wild habituated group of western lowland gorillas (Gorilla gorilla gorilla) in the Dzanga Sangha Protected Areas, Central African Republic. We examined 36 fecal samples from eight individuals, including samples before and after ATB treatment, and characterized the GI microbiome composition using Illumina-MiSeq sequencing of the bacterial 16S rRNA gene. The GI microbial profiles of samples from the same individuals before and after ATB administration indicate that the ATB treatment impacts GI microbiome stability and the relative abundance of particular bacterial taxa within the colonic ecosystem of wild gorillas. We observed a statistically significant increase in Firmicutes and a decrease in Bacteroidetes levels after ATB treatment. We found disruption of the fibrolytic community linked with a decrease of Ruminoccocus levels as a result of ATB treatment. Nevertheless, the nature of the changes observed after ATB treatment differs among gorillas and thus is dependent on the individual host. This study has important implications for ecology, management, and conservation of wild primates.

Proximate composition of milk from free-ranging mountain gorillas (Gorilla beringei beringei).

Published data on milk composition for nonhuman primates, especially great apes, are lacking. Milk composition data are important for understanding the physiology and evolution of mammalian milk production, as well as the nutritional requirements of infants. For many primate species these data have added relevance because of the need to hand raise infants orphaned by poaching or separated from their mothers in captivity. The proximate composition (dry matter (DM), protein, fat, sugar) of free-ranging mountain gorilla (MG) (Gorilla beringei beringei) milk was characterized from samples (N = 10) collected opportunistically during field procedures. The mean values for mid-lactation (1-50 months) milk samples from healthy MGs (N = 7) were: 10.7% DM, 1.9% fat, 1.4% crude protein, 6.8% sugar, and 0.53 kcal/g. These results are lower in fat and total energy than most other Hominidae, including humans. One early-lactation sample was high in protein content while the composition of two samples from gorillas with poor health and suspected poor milk quality both deviated from the normal, mid-lactation pattern. This survey adds to the data available for primate milk composition and suggests that wild MG infants normally consume milk that is lower in fat and total energy than human milk.

Real-time PCR detection of Campylobacter spp. In free-ranging mountain gorillas (Gorilla beringei beringei).

Health monitoring of wildlife populations can greatly benefit from rapid, local, noninvasive molecular assays for pathogen detection. Fecal samples collected from free-living Virunga mountain gorillas (Gorilla beringei beringei) between August 2002 and February 2003 were tested for Campylobacter spp. DNA using a portable, real-time polymerase chain reaction (PCR) instrument. A high prevalence of Campylobacter spp. was detected in both individually identified (22/26=85%) and nest-collected samples (68/114=59.6%), with no statistically significant differences among different gorilla sexes or age classes or between tourist-visited versus research gorilla groups. The PCR instrument was able to discriminate two distinct groups of Campylobacter spp. in positive gorilla samples based on the PCR product fluorescent-probe melting profiles. The rare type (6/90 positives, 7%, including three mixed cases) matched DNA sequences of Campylobacter jejuni and was significantly associated with abnormally soft stools. The more common type of positive gorilla samples (87/90 positives, 97%) were normally formed and contained a Campylobacter sp. with DNA matching no published sequences. We speculate that the high prevalence of Campylobacter spp. detected in gorilla fecal samples in this survey mostly reflects previously uncharacterized and nonpathogenic intestinal flora. The real-time PCR assay was more sensitive than bacterial culture with Campylobacter-specific media and commercially available, enzyme immunoassay tests for detecting Campylobacter spp. in human samples.

Fatty acid composition of wild anthropoid primate milks.

Fatty acids in milk reflect the interplay between species-specific physiological mechanisms and maternal diet. Anthropoid primates (apes, Old and New World monkeys) vary in patterns of growth and development and dietary strategies. Milk fatty acid profiles also are predicted to vary widely. This study investigates milk fatty acid composition of five wild anthropoids (Alouatta palliata, Callithrix jacchus, Gorilla beringei beringei, Leontopithecus rosalia, Macaca sinica) to test the null hypothesis of a generalized anthropoid milk fatty acid composition. Milk from New and Old World monkeys had significantly more 8:0 and 10:0 than milk from apes. The leaf eating species G. b. beringei and A. paliatta had a significantly higher proportion of milk 18:3n-3, a fatty acid found primarily in plant lipids. Mean percent composition of 22:6n-3 was significantly different among monkeys and apes, but was similar to the lowest reported values for human milk. Mountain gorillas were unique among anthropoids in the high proportion of milk 20:4n-6. This seems to be unrelated to requirements of a larger brain and may instead reflect species-specific metabolic processes or an unknown source of this fatty acid in the mountain gorilla diet.

Brain structure variation in great apes, with attention to the mountain gorilla (Gorilla beringei beringei).

This report presents data regarding the brain structure of mountain gorillas (Gorilla beringei beringei) in comparison with other great apes. Magnetic resonance (MR) images of three mountain gorilla brains were obtained with a 3T scanner, and the volume of major neuroanatomical structures (neocortical gray matter, hippocampus, thalamus, striatum, and cerebellum) was measured. These data were included with our existing database that includes 23 chimpanzees, three western lowland gorillas, and six orangutans. We defined a multidimensional space by calculating the principal components (PCs) from the correlation matrix of brain structure fractions in the well-represented sample of chimpanzees. We then plotted data from all of the taxa in this space to examine phyletic variation in neural organization. Most of the variance in mountain gorillas, as well as other great apes, was contained within the chimpanzee range along the first two PCs, which accounted for 61.73% of the total variance. Thus, the majority of interspecific variation in brain structure observed among these ape taxa was no greater than the within-species variation seen in chimpanzees. The loadings on PCs indicated that the brain structure of great apes differs among taxa mostly in the relative sizes of the striatum, cerebellum, and hippocampus. These findings suggest possible functional differences among taxa in terms of neural adaptations for ecological and locomotor capacities. Importantly, these results fill a critical gap in current knowledge regarding great ape neuroanatomical diversity.

Comparison of storage methods for reverse-transcriptase PCR amplification of rotavirus RNA from gorilla (Gorilla g. gorilla) fecal samples.

Detection of enteric viral nucleic acids in preserved gorilla fecal specimens was investigated using reverse transcription polymerase chain reaction (rt-PCR). A commercially available viral RNA extraction kit was used to isolate nucleic acids from captive gorilla fecal samples seeded with rotavirus and stored in ethanol, formalin, a commercial RNA preservation solution, guanidine thiocyanate buffer (GT), and samples dried in tubes containing silica gel. Nucleic acids were extracted at 1, 7, 70 and 180 days and used for rt-PCR amplification of specific rotavirus RNA sequences. Successful rt-PCR amplification of the target product varied according to storage conditions, and storage time. Only samples stored in GT gave 100% positive results at 180 days. It is recommended that fecal samples be collected in GT for viral RNA analysis.