Effects of rainfall, host demography, and musth on strongyle fecal egg counts in African elephants (Loxodonta africana) in Namibia

Wild African elephants (Loxodonta africana) are commonly infected with intestinal strongyle parasites. Our objective was to determine baseline fecal strongyle egg counts for elephants in the northeast region of Etosha National Park, Namibia and determine if these numbers were affected by annual rainfall, elephant demography (age of individuals and composition of groups), and hormonal state of males. We found that matriarchal family group members have significantly higher fecal egg counts than male elephants (bulls). Among family group members, strongyle egg counts increased with age, whereas among bulls, strongyle egg counts decreased with age. Years of higher rainfall were correlated with decreased numbers of strongyle eggs among bulls. Finally, bulls were not affected by their physiologic (hormonal) status (musth vs. nonmusth). These results suggest that infection by strongyle parasites in Namibian African elephants is a dynamic process affected by intrinsic and extrinsic factors including host demography and rainfall.     

Factors influencing the fecal egg and oocyst counts of parasites of wild European rabbits Oryctolagus cuniculus (L.) in Southern Western Australia

Abundance of intestinal parasites was monitored by fecal egg and oocyst counts for samples of wild rabbits Oryctolagus cuniculus with different levels of imposed female sterility from 12 populations in southwestern Australia. Differences in egg counts of Trichostrongylus retortaeformis between seasons and age groups were dependent on the sex of the host. Pregnancy may have been responsible for these differences because egg counts were consistently higher in intact females than in females surgically sterilized by tubal ligation. Egg counts for Passalurus ambiguus were influenced by season and host age but there were no differences between sexes or between intact and sterilized female rabbits. No differences were detected in the oocyst counts of the 8 species of Eimeria between male and female rabbits or between intact and sterilized females. Seasonal differences were detected in oocyst counts of Eimeria flavescens and Eimeria stiedai. The overwhelming determinant of coccidian oocyst counts was host age, with 6 species being much more abundant in rabbits up to 4 mo of age. There was a suggestion that egg counts of T. retortaeformis and oocyst counts of several species of Eimeria were reduced in populations where rabbit numbers had been depressed for at least 2 yr, but there was no evidence that short-term variations in rabbit numbers had a measurable effect on parasite abundance.     

Effect of Selenium Yeast Supplementation on Naturally Acquired Parasitic Infection in Ewes

Gastrointestinal parasites cause substantial economic losses in pasture-based sheep production systems. Supranutritional organic selenium (Se) supplementation may be beneficial because it improves immune responses to pathogens. To evaluate the effect of Se-yeast supplementation on gastrointestinal parasite load, 30 ewes per treatment group were drenched weekly with no Se, 4.9 mg Se/week as Se yeast (maximum FDA-allowed concentration), or supranutritional concentrations of Se yeast (14.7 and 24.5 mg Se/week) starting early fall for 85 weeks. Fecal samples were collected at weeks 63, 66, 78, and 84 and counted for total trichostrongyle-type eggs and Haemonchus contortus eggs (in samples with ≥200 trichostrongyle eggs/g feces). During breeding season (fall), ewes were kept on pasture; ewes receiving 24.5 mg Se/week had lower fecal trichostrongyle egg counts (93?±?40 eggs/g feces) compared with ewes receiving no Se (537?±?257 eggs/g feces; P?=?0.007) or ewes receiving 4.9 mg Se/week as Se yeast (398?±?208 eggs/g feces; P?=?0.03). In winter, fecal trichostrongyle egg counts decreased, and group differences were not apparent. During lambing season (spring), ewes were kept in the barn and fecal trichostrongyle egg counts increased, although no group differences were observed. However, none of the ewes receiving supranutritional Se yeast, and with trichostrongyle egg counts ≥200 eggs/g of feces, but four of the ewes receiving lower Se dosages had H. contortus egg counts ≥1,000 eggs/g feces (P?=?0.04). Our results suggest that supranutritional Se-yeast supplementation may enhance resistance to naturally occurring H. contortus gastrointestinal parasitism in sheep.     

Faecal egg counts and nemabiome metabarcoding highlight the genomic complexity of equine cyathostomin communities and provide insight into their dynamics in a Scottish native pony herd

Understanding the composition of gastrointestinal nematode communities may help to mitigate or exploit parasite adaptations within their host. We have used nemabiome deep amplicon sequencing of internal transcribed spacer-2 (ITS-2) ribosomal DNA to describe the temporal and host species composition of gastrointestinal nematode communities following sampling of six Scottish ponies across 57 months. In the absence of parasite control, each horse showed seasonal trends of increases and decreases in faecal egg counts, consistent with the epidemiology of equine strongylid parasites, however, the composition of parasites within individuals changed over time. Sixteen presumptive strongylid species were identified in each of the horses, 13 of which were distributed in a complex clade together with small numbers of amplicon sequences which could not be classified beyond the Cyathostominae subfamily level. Egg shedding of seven trichostrongylid species, which had previously been identified in co-grazed Soay sheep, was identified during the early spring. Faecal egg counts and the percentage of amplicon sequences assigned to each gastrointestinal nematode species were combined to describe their relative abundance across both host and time. Significant differences in species diversity between horses and between months were observed, being greatest from March to May and least from October to December. The magnitude of the individual horse effect varied between months and, conversely, the magnitude of the seasonal effect varied between individual horses. The most abundant gastrointestinal nematode in each of the horses was Cylicostephanus longibursatus (46.6% overall), while the abundance of the other strongylid species varied between horses and relative to each other. Patent C. longibursatus infections over the winter months might represent a genetic adaptation towards longer adult worm survival, or a lower rate of developmental arrest in the autumn. This study provides insight into highly complex phylogenetic relationships between closely related cyathostomin species; and describes the dynamics of egg shedding and pasture contamination of co-infecting equine gastrointestinal nematode communities. The results could be applied to determine how climatic and management factors affect the equilibrium between hosts and their parasites, and to inform the development of sustainable gastrointestinal nematode control strategies for different host species.     

Intestinal parasites and bacteria of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda

A survey in 1994 examined intestinal helminths and bacterial flora of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda. Parasites and bacteria were identified to genus in the feces of two groups of tourist-habituated and one group of non-tourist-habituated mountain gorillas. Eggs were identified as those of an anoplocephalid cestode, and nematode eggs representative of the genera: Trichuris, Ascaris, Oesophagostomum, Strongyloides, and Trichostrongylus. This is the first report of Ascaris lumbricoides-like eggs in mountain gorillas. Fecal samples (n=76) from all groups contained helminth eggs, with strongyle eggs and anoplocephalid eggs being the most common. Salmonella and Campylobacter were found in both gorilla groups. Regular long-term non-invasive fecal monitoring of the populations of mountain gorillas is essential for the prevention and identification of potential health threats by intestinal parasites and bacteria in this highly endangered subspecies.This revised version was published online in April 2005 with corrections to the cover date of the issue.     

The Intestinal Entodiniomorph Ciliates of Wild Lowland Gorillas (Gorilla gorilla gorilla) in Gabon,West Africa

Examination of 109 fecal samples from wild lowland gorillas revealed the presence of five species of entodiniomorph ciliates: Troglodytella ahrassarti, Troglodytella gorillae, and three unclassified species. These latter three species were also found in the feces of a captive gorilla in Gabon and are considered to be intestinal parasites or commensals.     

Monitoring the reproductive status of female gorillas (Gorilla gorilla gorilla) by measuring the steroid hormones in fecal samples

The reproductive status of female gorillas (Gorilla gorilla gorilla) was estimated by measuring the sex steroid hormones in fecal samples instead of in blood samples. Fecal samples from female gorillas were used to examine the reliability of this non-invasive assay system, which included the extraction method for estradiol-17β (E₂) and progesterone (P) from fecal samples. Fecal samples from three female gorillas were collected daily for about 55 days, and fecal E₂ and P were assayed to clarify the fluctuation patterns of these steroids in the feces. Fecal sampling from one female was repeated for another 50-day period (starting 75 days after the end of the first observation period) and assayed to confirm if the menstrual cycle of this subject was ovulatory. Although fecal E₂ concentration measurements were quantitative by using this assay system, fecal P concentration measurements were semi-quantitative. Relative amounts of fecal P in fecal samples were estimated by using the values of B/B₀ (bound/total binding in the radioimmunoassay system). Two of the four fluctuation patterns of fecal hormones observed throughout the menstrual cycle for the three female gorillas were typical for normal ovulatory cycles. In the subject observed for two periods, one pattern was typical and the other atypical. The results show that this non-invasive method is simple and practical for monitoring the reproductive status of great apes as well as Old World monkeys.     

Intestinal Parasites of Free-ranging,Semicaptive,and Captive <Emphasis Type="Italic">Pongo abelii</Emphasis> in Sumatra,Indonesia

We collected fecal samples from 32 free-ranging, 19 semicaptive, and 54 captive Sumatran orangutans on Sumatra from 1998 until 2004 and screened them for gastrointestinal parasites. Our objectives were to compare the intestinal parasites of free-ranging, semicaptive, and captive orangutans and to evaluate the risk of parasite transmission in orangutan reintroduction programs. We identified 4 genera of Protozoa, 7 genera of nematodes, 1 trematode sp., and 1 cestode sp. The prevalence of Balantidium coli in free-ranging orangutans was significantly higher than in captive individuals. However, the prevalence of Strongyloides sp. was higher in captive than in free-ranging orangutans. Free-ranging female orangutans had a significantly higher total prevalence of intestinal parasites than that of males. We found no significant difference between parasite prevalences in different age groups. Compared to gorillas and chimpanzees, orangutans carry a smaller variety of protozoan and nematode species. Strongyloides sp. infections form the highest risk in reintroduction programs as crowding, ground-dwelling, and poor hygiene in captive and semicaptive orangutans may cause a constant reinfection.     

Parasites of free-ranging black howler monkeys (Alouatta pigra) from Belize and Mexico

Parasites are important members of the ecological web within which an animal lives, and can be used as indicators of ecosystem health. However, few baseline parasitological data are available for free-ranging animals, particularly for the black howler monkey (Alouatta pigra). In this study a total of 283 fecal samples were collected from 50 individually identified A. pigra during 2003 and 2004 and examined for parasites. The samples were processed using standard quantitative centrifugation concentration techniques, with sugar and zinc sulfate used as flotation media. The slides were examined using bright-field and phase microscopy. Antigen capture enzyme-linked immunosorbent assays (ELISAs) were used to detect protozoa. Four parasites were detected: 1) Controrchis biliophilus (Dicrocoeliidae), 2) Trypanoxyuris minutus (Oxyuridae), 3) Giardia sp. (Hexamitidae), and 4) Entamoeba sp. (Endamoebidae). Controrchis biliophilus was detected in 80% (wet season) and 81% (dry season) of the A. pigra samples; Trypanoxyuris minutus was detected in 8% (wet season) and 27% (dry season) of samples; and Giardia sp. was detected in 40% (wet season) and 27% (dry season) of samples. For the first time, DNA from Giardia sp.-positive fecal samples was extracted from A. pigra. Alouatta pigra individuals that lived near human settlements in Belize were infected with Giardia duodenalis (syn. G. lamblia, G. intestinalis) Assemblages A and B. These results suggest that G. duodenalis is transmitted from people and/or domestic animals to A. pigra.     

Evidence for genetic control of nematode egg-shedding rates in calves

Differences in nematode fecal egg counts from 167 purebred Angus calves born in 1986 and 133 born in 1987 that had been naturally exposed to infection on pasture were analyzed for sire effects. The calves were sired by 26 different bulls, all of which were related. Differences among fecal egg counts were attributable to sires (P less than 0.0002), to age of the calf (P less than 0.0007), to age of dam (P less than 0.05), and to collection year (P less than 0.0001). No variation in fecal egg count was attributable to calf sex (P greater than 0.23). After accounting for the effects of year, age of calf, and age of dam, heritability was estimated to be 29% (SE = 18%). It was concluded that a paternal contribution to the genome of each calf played an important role in determining average fecal egg output of the sire group. With heritability at 29%, selection against higher fecal egg counts or selection for lower fecal egg counts would be expected to produce measurable genetic change in a population.     

Evaluation of different storage methods to characterize the fecal bacterial communities of captive western lowland gorillas (Gorilla gorilla gorilla)

Freezing is considered to be the best method for long-term storage of bacterial DNA from feces; however this method cannot be usually applied for samples of wild primates collected in the challenging conditions of the tropical forest. In order to find an alternative conservation method of fecal samples from wild great apes, we compared freezing with other fixation methods. Fecal samples from 11 captive gorillas (Gorilla gorilla gorilla) from three Czech Zoos were stored using freezing, RNA Stabilization Reagent (RNAlater), and 96% ethanol. Subsequently, the samples were examined using culture-independent methods (PCR-DGGE, and Real-time PCR) to qualitatively and quantitatively assess fecal microbiota composition and to compare differences among the storage methods. Noticeably, freezing samples resulted in the highest recoveries of DNA. No significant differences in DNA recovery were found between freezing and using RNAlater; however, significantly lower DNA concentrations were recovered from samples stored in 96% ethanol. Using PCR-DGGE we found that either 96% ethanol, RNAlater or freezing were suitable for preserving bacterial DNA; however fingerprints obtained from RNAlater storage were more similar to those obtained from the frozen method; in comparison to the patterns resulting from storing samples in ethanol. Using qPCR, frozen samples yielded the highest values of bacterial counts, with the exception of Enterobacteriaceae, which showed the highest numbers using samples stored in ethanol. Sequences of amplicons obtained from PCR-DGGE belonged to the families Clostridiaceae, Lactobacillaceae, Staphylococcaceae, and Lachnospiraceae, phylum Firmicutes; however most amplicons showed sequence similarity to previously uncultured microorganisms. Bacteria belonging to the phylum Firmicutes were the most frequently identified species in the fecal bacterial communities of captive western gorillas. The study showed that RNAlater is an optimal storage method when freezing is not possible.     

Ant eating by eastern lowland gorillas

Evidence was obtained that Eastern lowland gorillas feed regularly on ants in the lowland forests of eastern Zaire. The six species of ants that may have been consumed by the gorillas were identified as Ponerinae, which possess a painful sting. Gorillas consumed the ants in both rainy and dry seasons, and fragments of ants were found in fecal samples from gorillas of all age-sex classes. Field signs indicated that the gorillas search intensively ants in primary and ancient secondary forests. Such searching may stimulate the gorillas to range through various types of vegetation and, thus, it may contribute to elongation of the distances that they travel daily.     

Effects of preintestinal larval antigenic stimuli on the generation of intestinal immunity in Strongyloides ratti infection in rats

Generation of intestinal immunity by antigenic stimulation with preintestinal, tissue-migrating larvae was investigated in the Strongyloides ratti-rat model. The results of daily fecal egg counts showed that the intestinal immunity against adult worms could be partially generated by priming with preintestinal migrating larvae. A further study demonstrated that this partial reduction of daily fecal egg count was mainly the result of inhibitory effects on the fecundity of the parasitic females, although the expulsion of the parasite from the gut could be advanced by several days. After tertiary immunization with preintestinal larvae, no significant potentiation in the protection was observed when compared with the rats treated by primary immunization alone.     

Ranging Patterns of a Western Gorilla Group During Habituation to Humans in the Dzanga-Ndoki National Park,Central African Republic

The ranging patterns of western gorillas have been described in relation to their more frugivorous diet as compared to mountain gorillas. However, the lack of data from habituated groups prevents a full understanding of their ranging behavior and its implications for western gorilla social behavior. Unhabituated gorillas often flee from approaching researchers, possibly resulting in longer daily ranges and home range expansions and/or shifts. I report on the influence of habituation on the ranging patterns of a western gorilla group. I analyzed progress in habituation through changes in gorilla reactions, displayed upon detecting the observers. I measured daily path length and home range while following the group's trails and monitored diet via fecal analyses and direct observations. During the study period, habituation progressed and the gorillas increasingly ignored the arrival of observers. As a result, daily path lengths were longer during the early stages of habituation, when the gorillas were avoiding observers. There was no range expansion or shift, though the measure is more difficult to investigate, being subject to error due to variation in sample size. We recorded seasonal changes in the consumption of fruit by gorillas, but no direct effect on ranging patterns is detectable with the data available, which is likely a consequence of the combined effect of habituation and seasonality on group movements. The findings are not only important for understanding the extent of human influence while conducting research on wild gorillas but also suggest the need for caution when interpreting results from non-habituated gorillas.     

Foods consumed by sympatric populations ofGorilla g. gorilla andPan t. troglodytes in Gabon: Some preliminary data

Data on foods consumed by gorillas and chimpanzees living in primary forest in Gabon were collected, mainly by examination of the contents of feces. Gorillas ate fruit very regularly (some fruit remains were present in 97.6% of 246 fecal samples examined), in addition to leaves, stems, pith, and bark. Some fruit remains were present in all chimpanzee fecal samples examined. Mean numbers of fruit species per fecal sample were 2.5 for gorillas and 2.1 for chimpanzees. Sixty percent of all identified foods recorded for gorillas were recorded for chimpanzees as well. Our results indicate that important differences in diet exist between western lowland gorillas and the eastern gorilla populations of Kahuzi-Biega and the Virunga Volcanoes. It is now clear that western gorillas cannot be accurately classed as folivores.     

Diet of Grauer's Gorillas in the Montane Forest of Kahuzi,Democratic Republic of Congo

We describe the diet of a semihabituated group of Grauer's gorillas (Gorilla beringei graueri) inhabiting the montane forest of Kahuzi-Biega National Park, Democratic Republic of Congo, based on direct observations, feeding remains in their fresh trails, and fecal samples collected over 9 yr. We examined fruit availability in their habitat; consumption of fruit, vegetative, and animal food; and daily intake of vegetative plant food using a transect, fruit monitoring trails, fecal analysis, and tracing of the animal's daily trails between consecutive nest sites. The fruit food repertoire of Kahuzi gorillas resembles that of western and eastern lowland gorillas inhabiting lowland tropical forests, while their vegetative food repertoire resembles that of mountain gorillas inhabiting montane forests. Among 236 plant foods (116 species), leaves, pith, and barks constitute the major parts (70.2%), with fruit making up the minor part (19.7%). About half (53.2%) of the total fecal samples included fruit remains. The gorillas used leaves, stems and other vegetative plant parts as staples. Their fruit intake was similar to that reported for mountain gorillas in Bwindi. They ate animal foods, including earthworms, on rare occasions. Variation in fruit consumption was positively associated with variation in fruit production. The gorillas ate fig fruits frequently; fig intake is positively correlated with that of other fruits, and figs were not fallback foods. They relied heavily on bamboo shoots on a seasonal basis; however, no bamboo shoots were available for several years after a major flowering event. Our results support the argument that variation in gorilla diets mostly reflects variation in vegetational composition of their habitats.     

Species and sex identification of western lowland gorillas (Gorilla gorilla gorilla), eastern lowland gorillas (Gorilla beringei graueri) and humans

Methods for the identification of the sex and species of individuals from samples non-invasively taken from humans and gorillas were established. Amplification of a segment of amelogenin (AMG), which is an X–Y homologous gene, using two pairs of primers from human AMG, revealed both X- and Y-specific bands. The possibility of sex identification was examined by typing the AMG gene using hair and fecal samples from captive western lowland gorillas (Gorilla gorilla gorilla) in Japan and hair samples from wild eastern lowland gorillas (Gorilla beringei graueri) in the Kahuzi-Biega National Park, Democratic Republic of Congo, which were sexed by direct observation. Species-specific bands of AMG in gorillas and humans were identified by restriction fragment length polymorphisms analysis. These tests could be used for sexing unidentified individuals of wild western and eastern lowland gorillas, and screening contamination of human DNA from non-invasively acquired samples.     

Effects of group dynamics and diet on the ranging patterns of a western gorilla group (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic

This study describes how group dynamics and diet have influenced the ranging patterns of a western gorilla group at Bai Hokou, Central African Republic. The results are compared with those from an earlier study [Cipolletta, International Journal of Primatology, 2003], when the same group was larger and undergoing the process of habituation to humans. Data were obtained from maps of the gorillas' travel routes, direct observations, and analysis of fecal samples. Through the years, the group has experienced a decrease in size, from eight to three individuals, with periods of membership fluctuation. The male's search for new mates resulted in a larger home range than was recorded when the group consisted of more individuals. Moreover, despite an average group size of three throughout this study, the monthly range and mean daily path length (DPL) were also larger when the group was acquiring/losing members in new areas, than when no new members joined or left the group. Fruit was consumed year-round, although more heavily so during wet months. The influence of fruit consumption on the ranging patterns was concealed initially by the effect of habituation [Cipolletta, International Journal of Primatology, 2003], and later (at least partially) by the male's search for new mates. In the last 14 months of the study, when the group numbered only three individuals and was ranging in a restricted area, the average DPL, but not the monthly range, increased when the gorillas were consuming more fruit.     

Egg Laying Capacity of Haplorchis taichui (Digenea: Heterophyidae) in Humans

Quantitative fecal egg counts represented as the number of eggs per gram of feces (EPG) are generally a reliable parameter to estimate the worm burden of intestinal and hepatic parasitoses. Although Haplorchis taichui (Digenea: Heterophyidae) is one of the most common minute human intestinal flukes, little is known about the relationship between EPG and the actual worm burden in patients or the severity of the disease. In the present study, fecal samples were collected from 25 villagers in northern Thailand before and after praziquantel treatment. The EPG values of each participant were determined by the modified cellophane thick smear method, and adult worms were collected from the whole stool after the treatment. Eggs per day per worm (EPDPW) of H. taichui were estimated 82 from egg counts and expelled worms. The EPG was not well correlated with the worm burden, and a reverse correlation was observed between the EPDPW and the worm burden.     

Genetic diversity of primate strongylid nematodes: Do sympatric nonhuman primates and humans share their strongylid worms?

The close phylogenetic relationship between humans and nonhuman primates (NHPs) can result in a high potential for pathogen exchange. In recent decades, NHP and human interactions have become more frequent due to increasing habitat encroachment and ecotourism. Strongylid communities, which include members of several genera, are typically found in NHPs. Using optimized high‐throughput sequencing for strain‐level identification of primate strongylids, we studied the structure of strongylid communities in NHPs and humans co‐habiting a tropical forest ecosystem in the Central African Republic. General taxonomic assignment of 85 ITS‐2 haplotypes indicated that the studied primates harbour at least nine genera of strongylid nematodes, with Oesophagostomum and Necator being the most prevalent. We detected both host‐specific and shared strongylid haplotypes. Skin‐penetrating Necator gorillaehaplotypes were shared between humans and gorillas but Necator americanus were much more restricted to humans. Strongylid communities of local hunter‐gatherers employed as trackers were more similar to those of gorillas compared to their relatives, who spent more time in villages. This was due to lower abundance of human‐origin N. americanus in both gorillas and trackers. Habituated gorillas or those under habituation did not show larger overlap of strongylids with humans compared to unhabituated. We concluded that the occurrence of the human‐specific strongylids in gorillas does not increase with direct contact between gorillas and humans due to the habituation. Overall, our results indicate that the degree of habitat sharing between hosts, together with mode of parasite transmission, are important factors for parasite spillover among primates.