High frequency of leaf swallowing and its relationship to intestinal parasite expulsion in "village" chimpanzees at Bulindi, Uganda

Relationships between Bitter Taste Receptor Gene Evolution, Diet, and Gene Repertoire in Primates

Bitter taste perception plays a critical role in deterring animals from consuming harmful and toxic substances. To characterize the evolution of primate Tas2r, test the generality of Tas2r duplication in Cercopithecidae species, and examine whether dietary preferences have shaped the Tas2r repertoire of primate species, we identified Tas2r in the genomes of 35 primate species, including 16 Cercopithecidae, 6 Hominidae, 4 Cebidae, 3 Lemuridae, and 6 other species. The results showed that the total number of primate Tas2r ranged from 27 to 51, concentrating on 2 to 4 scaffolds of each species. Closely related genes were tandemly duplicated in the same scaffold. Phylogenetic construction revealed that Tas2r can be divided into 21 clades, including anthropoid-, Strepsirrhini-, and Cercopithecidae-specific Tas2r duplications. Phylogenetically independent contrast analysis revealed that the number of intact Tas2r significantly correlated with feeding preferences. Altogether, our data support diet as a driver of primate Tas2r evolution, and Cercopithecidae species have developed some specific Tas2r duplication during evolution. These results are probably because most Cercopithecidae species feed on plants containing many toxins, and it is necessary to develop specialized Tas2r to protect them from poisoning.

Active self-treatment of a facial wound with a biologically active plant by a male Sumatran orangutan

Although self-medication in non-human animals is often difficult to document systematically due to the difficulty of predicting its occurrence, there is widespread evidence of such behaviors as whole leaf swallowing, bitter pith chewing, and fur rubbing in African great apes, orangutans, white handed gibbons, and several other species of monkeys in Africa, Central and South America and Madagascar. To the best of our knowledge, there is only one report of active wound treatment in non-human animals, namely in chimpanzees. We observed a male Sumatran orangutan (Pongo abelii) who sustained a facial wound. Three days after the injury he selectively ripped off leaves of a liana with the common name Akar Kuning (Fibraurea tinctoria), chewed on them, and then repeatedly applied the resulting juice onto the facial wound. As a last step, he fully covered the wound with the chewed leaves. Found in tropical forests of Southeast Asia, this and related liana species are known for their analgesic, antipyretic, and diuretic effects and are used in traditional medicine to treat various diseases, such as dysentery, diabetes, and malaria. Previous analyses of plant chemical compounds show the presence of furanoditerpenoids and protoberberine alkaloids, which are known to have antibacterial, anti-inflammatory, anti-fungal, antioxidant, and other biological activities of relevance to wound healing. This possibly innovative behavior presents the first systematically documented case of active wound treatment with a plant species know to contain biologically active substances by a wild animal and provides new insights into the origins of human wound care.

Anoplocephalid tapeworms in mountain gorillas (Gorilla beringei beringei) inhabiting the Volcanoes National Park, Rwanda

Cestodes of the family Anoplocephalidae parasitize a wide range of usually herbivorous hosts including e.g. rodents, ungulates, primates, elephants and hyraxes. While in some hosts, the epidemiology of the infection is well studied, information is lacking in others. In this study of mountain gorillas in the Virunga Massif, an extensive sample set comprising adult cestodes collected via necropsies, proglottids shed in feces, and finally, fecal samples from both night nests and identified individuals were analysed. Anoplocephala gorillae was the dominant cestode species detected in night nest samples and individually known gorillas, of which only 1 individual hosted a Bertiella sp. It was shown that the 2 species can be distinguished through microscopy based on egg morphology and polymerase chain reaction (PCR) assays for diagnostics of both species were provided. Sequences of mitochondrial (cox 1) and nuclear (ITS1, 18S rDNA, 28S rDNA) markers were used to evaluate the phylogenetic position of the 2 cestodes detected in mountain gorillas. Both types of fecal samples, from night nests and from identified individuals, provided comparable information about the prevalence of anoplocephalid cestodes, although the analysis of samples collected from identified gorilla individuals showed significant intra-individual fluctuation of A. gorillae egg shedding within a short period. Therefore, multiple samples should be examined to obtain reliable data for wildlife health management programmes, especially when application of anthelmintic treatment is considered. However, while A. gorillae is apparently a common symbiont of mountain gorillas, it does not seem to impair the health of its host.

What fecal analyses reveal about Manniophyton fulvum consumption in LuiKotale bonobos (Pan paniscus): A medicinal plant revisited

Observations of animals in the wild can result in the discovery of plants for human medicinal purposes. In this context, our closest relatives, the great apes, are of particular interest. The Euphorbiaceae Manniophyton fulvum possesses both phytochemical and biomechanical properties. Its use in the genus Pan (P. troglodytes; P. paniscus) is thought to be based on its mechanical properties promoting the egestion of intestinal parasites, but additional observations from different habitats where the behavior is performed may shed more light on its true purpose. To improve our understanding of what triggers this behavior, we investigated M. fulvum consumption in wild bonobos at LuiKotale, Democratic Republic of the Congo between December 2018 and July 2020. Specifically, we tested the hypothesis that M. fulvum ingestion is related to gastro-intestinal parasite expulsion. Of 649 focal follows of 37 individuals from two habituated communities, consumption of M. fulvum was observed on 111 days (N = 507), independent of seasons, environmental factors and the plant's availability. A total of 588 fecal samples were assessed for the presence/absence of gastro-intestinal parasites. We found strongyle eggs in 2.89% of samples and their presence was not associated with the ingestion of M. fulvum or environmental conditions. We discuss the importance of seasonality in the life cycle of strongyle species that may influence the pattern of M. fulvum consumption observed at LuiKotale. Our data open additional perspectives concerning behavioral parameters such as the existence of a cultural component when comparing ingestion behavior between communities.

Sparse Evidence for Giardia intestinalis, Cryptosporidium spp. and Microsporidia Infections in Humans, Domesticated Animals and Wild Nonhuman Primates Sharing a Farm-Forest Mosaic Landscape in Western Uganda

Zoonotic pathogen transmission is considered a leading threat to the survival of non-human primates and public health in shared landscapes. Giardia spp., Cryptosporidium spp. and Microsporidia are unicellular parasites spread by the fecal-oral route by environmentally resistant stages and can infect humans, livestock, and wildlife including non-human primates. Using immunoassay diagnostic kits and amplification/sequencing of the region of the triosephosphate isomerase, small ribosomal subunit rRNA and the internal transcribed spacer genes, we investigated Giardia, Cryptosporidium, and microsporidia infections, respectively, among humans, domesticated animals (livestock, poultry, and dogs), and wild nonhuman primates (eastern chimpanzees and black and white colobus monkeys) in Bulindi, Uganda, an area of remarkably high human-animal contact and spatial overlap. We analyzed 137 fecal samples and revealed the presence of G. intestinalis assemblage B in two human isolates, G. intestinalis assemblage E in one cow isolate, and Encephalitozoon cuniculi genotype II in two humans and one goat isolate. None of the chimpanzee and colobus monkey samples were positive for any of the screened parasites. Regular distribution of antiparasitic treatment in both humans and domestic animals in Bulindi could have reduced the occurrence of the screened parasites and decreased potential circulation of these pathogens among host species.

Paleomedicine and the Evolutionary Context of Medicinal Plant Use

Modern human need for medicines is so extensive that it is thought to be a deep evolutionary behavior. There is abundant evidence from our Paleolithic and later prehistoric past, of survival after periodontal disease, traumas, and invasive medical treatments including trepanations and amputations, suggesting a detailed, applied knowledge of medicinal plant secondary compounds. Direct archeological evidence for use of plants in the Paleolithic is rare, but evidence is growing. An evolutionary context for early human use of medicinal plants is provided by the broad evidence for animal self-medication, in particular, of non-human primates. During the later Paleolithic, there is evidence for the use of poisonous and psychotropic plants, suggesting that Paleolithic humans built on and expanded their knowledge and use of plant secondary compounds.

Zoonotic Enterobacterial Pathogens Detected in Wild Chimpanzees

Infectious diseases including those acquired through direct or indirect contact with people and livestock threaten the survival of wild great apes. Few studies have reported enterobacterial pathogens in chimpanzees. We used multiplex PCR to screen faeces of chimpanzees sharing a landscape with villagers and livestock in Bulindi, Uganda for Salmonella spp., enterohemorrhagic Escherichia coli (E. coli) and Shigella spp./enteroinvasive E. coli. All three potentially zoonotic pathogens were detected. Individual prevalence ranged between 7 and 20%, with most infections observed in mature male chimpanzees. These preliminary findings suggest detailed investigation of enterobacterial infections in people, primates and livestock in this ecosystem is warranted.

Gastrointestinal parasite infections and self-medication in wild chimpanzees surviving in degraded forest fragments within an agricultural landscape mosaic in Uganda

Monitoring health in wild great apes is integral to their conservation and is especially important where they share habitats with humans, given the potential for zoonotic pathogen exchange. We studied the intestinal parasites of wild chimpanzees (Pan troglodytes schweinfurthii) inhabiting degraded forest fragments amid farmland and villages in Bulindi, Uganda. We first identified protozoan and helminth parasites infecting this population. Sixteen taxa were demonstrated microscopically (9 protozoa, 5 nematodes, 1 cestode, and 1 trematode). DNA sequence analysis enabled more precise identification of larval nematodes (e.g. Oesophagostomum stephanostomum, O. bifurcum, Strongyloides fuelleborni, Necator sp. Type II) and tapeworm proglottids (genus Bertiella). To better understand the ecology of infections, we used multidimensional scaling analysis to reveal general patterns of association among parasites, climate, and whole leaf swallowing-a prevalent self-medicative behaviour at Bulindi linked to control of nodular worms (Oesophagostomum spp.). Prevalence of parasites varied with climate in diverse ways. For example, Oesophagostomum sp. was detected in faeces at higher frequencies with increasing rainfall but was most clearly associated with periods of low temperature. Certain parasites occurred together within chimpanzee hosts more or less frequently than expected by chance. For example, the commensal ciliate Troglodytella abrassarti was negatively associated with Balantidium coli and Oesophagostomum sp., possibly because the latter taxa make the large intestine less suitable for T. abrassarti. Whole leaves in faeces showed independent associations with the prevalence of Oesophagostomum sp., Strongyloides sp., and hookworm by microscopic examination, and with egestion of adult O. stephanostomum by macroscopic inspection. All parasites identified to species or genus have been reported in wild chimpanzees inhabiting less-disturbed environments than Bulindi. Nevertheless, several disease-causing taxa infecting these chimpanzees are potentially transmissible between apes and humans (e.g. rhabditoid and strongyle nematodes), underscoring the importance of identifying and reducing risks of pathogen exchange in shared landscapes.

Molecular features of hookworm larvae (Necator spp.) raised by coproculture from Ugandan chimpanzees and Gabonese gorillas and humans

Species composition of Necator hookworms was surveyed in (i) Ugandan chimpanzees living around farms and villages at Bulindi, (ii) Gabonese gorillas under habituation in Moukalaba-Doudou National Park (MDNP), and (iii) Gabonese villagers living adjacent to MDNP. Internal transcribed spacers (ITS) of rDNA and partial cytochrome c oxidase subunit 1 (Cox1) gene of mtDNA were analyzed from larvae obtained by coproculture. Three ITS types (I, II and III) and three Cox1 haplotype groups (A, B and C) were demonstrated. ITS type I and Cox1 haplotype group A, representing Necator americanus, were demonstrated in the hookworm larvae from Gabonese gorillas and humans, but not from Ugandan chimpanzees. Type II and haplotype groups B and C, presumably representing N. gorillae, were found in larvae from Ugandan chimpanzees and Gabonese gorillas and humans. These features were overall similar with those found previously in the Central African Republic. Meanwhile, type III was proven in a larva from a Gabonese gorilla as the first demonstration from a non-human primate. Cox1 haplotypes obtained from Ugandan chimpanzees formed a subgroup within group B, presumably reflecting dispersal and diversification processes of the apes.

Leaf swallowing and parasite expulsion in Khao Yai white-handed gibbons (Hylobates lar), the first report in an Asian ape species

Leaf swallowing behavior, known as a form of self-medication for the control of nematode and tapeworm infection, occurs widely in all the African great apes (Pan troglodytes schweinfurthii, P. t. troglodytes, P. t. verus, P. t. vellerosus, Pan paniscus, Gorilla gorilla graueri), except mountain gorillas. It is also reported to occur in a similar context across a wide array of other animal taxa including, domestic dogs, wolves, brown bears, and civets. Despite long-term research on Asian great and small apes, this is the first report of leaf swallowing in an Asian species, the white-handed gibbon (Hylobates lar) in Khao Yai National Park, central Thailand. We present the first evidence of leaf swallowing (Gironniera nervosa Planch CANNABACEA) behavior (N = 5 cases) and parasite (Streptopharagus pigmentatus) expulsion (N = 4 cases), recorded during 4,300 hr of direct animal observations during two distinct research projects. We recovered 4-18 rough, hairy, and hispid surfaced leaves from each sample, undigested and folded, from the freshly evacuated feces of five different individuals (2 males, 3 females, 5 to 34+ years old) living in three different social groups, between the hours of 06:00 to 10:30. Based on close inspection of the leaves, as observed in chimpanzees, it was clear that they were taken into the mouth, one at a time, folded and detached from the stem with the teeth before swallowing them whole. All instances occurred during the rainy season, the time when nematode worms were also found in the feces, although they were not found together with leaves in the same feces. These striking similarities in the details of leaf swallowing between white-handed gibbons and African great apes, and other animal species, suggest a similar self-medicative function.

Cars kill chimpanzees: case report of a wild chimpanzee killed on a road at Bulindi, Uganda

Roads have broadly adverse impacts on wildlife, including nonhuman primates. One direct effect is mortality from collisions with vehicles. While highly undesirable, roadkills provide valuable information on the health and condition of endangered species. We present a case report of a wild chimpanzee (Pan troglodytes schweinfurthii) killed crossing a road in Bulindi, Uganda, where chimpanzees inhabit forest fragments amid farmland. Details of the collision are constructed from eyewitness accounts of pedestrians. Physical examination of the cadaver indicated good overall body condition; at 40 kg, the deceased female was heavier than usual for an adult female East African chimpanzee. No external wounds or fractures were noted. Coprological assessment demonstrated infection by several gastrointestinal parasites commonly reported in living wild chimpanzees. Histopathology revealed eosinophilic enteritis and biliary hyperplasia potentially caused by parasite infection. However, eosinophilia was not widely spread into the submucosa, while egg/cyst counts suggested low-intensity parasite infections compared to healthy female chimpanzees of similar age in nearby Budongo Forest. No behavioral indicators of ill health were noted in the deceased female in the month prior to the accident. We conclude that cause of death was acute, i.e., shock from the collision, and was probably unrelated to parasite infection or any other underlying health condition. Notably, this female had asymmetrical polythelia, and, while nursing at the time of her death, had one functioning mammary gland only. In Uganda, where primates often inhabit human-dominated landscapes, human population growth and economic development has given rise to increasing motor traffic, while road development is enabling motorists to travel at greater speeds. Thus, the danger of roads to apes and other wildlife is rising, necessitating urgent strategies to reduce risks. Installation of simple speed-bumps-common on Ugandan roads-would be effective in reducing risks to wildlife, and would also make roads safer for human pedestrians.

Intestinal Helminths of Wild Bonobos in Forest-Savanna Mosaic: Risk Assessment of Cross-Species Transmission with Local People in the Democratic Republic of the Congo

Phylogenetic and geographic proximities between humans and apes pose a risk of zoonotic transmission of pathogens. Bonobos (Pan paniscus) of the Bolobo Territory, Democratic Republic of the Congo, live in a fragmented forest-savanna mosaic setting, a marginal habitat for this species used to living in dense forests. Human activities in the forest have increased the risk of contacts between humans and bonobos. Over 21 months (September 2010-October 2013), we monitored intestinal parasites in bonobo (n = 273) and in human (n = 79) fecal samples to acquire data on bonobo parasitology and to assess the risk of intestinal helminth transmission between these hosts. Coproscopy, DNA amplification, and sequencing of stored dried feces and larvae were performed to identify helminths. Little difference was observed in intestinal parasites of bonobos in this dryer habitat compared to those living in dense forests. Although Strongylids, Enterobius sp., and Capillaria sp. were found in both humans and bonobos, the species were different between the hosts according to egg size or molecular data. Thus, no evidence of helminth transmission between humans and bonobos was found. However, because humans and this threatened species share the same habitat, it is essential to continue to monitor this risk.

Molecular identification of Oesophagostomum spp. from 'village' chimpanzees in Uganda and their phylogenetic relationship with those of other primates

Oesophagostomum spp. are parasitic nematodes of mammals, including humans and other primates. To identify species and determine phylogeny, we analysed DNA sequences of adult and larval Oesophagostomum from wild chimpanzees in Bulindi, Uganda, which inhabit degraded forest fragments amid villages. Oesophagostome larvae and/or eggs from baboons in Tanzania and South Africa and from a Japanese macaque were also sequenced. Based on the internal transcribed spacer 2 (ITS2) of nuclear ribosomal DNA and partial cytochrome c oxidase subunit 1 gene (Cox1) of mtDNA, O. stephanostomum and O. bifurcum were identified from chimpanzees. Bulindi is the second locality where molecular detection of O. bifurcum in wild chimpanzees has been made. While most O. stephanostomum had ITS2 genotypes recorded previously, three new genotypes were detected. Among four ITS2 genotypes of O. bifurcum from chimpanzees, one was identical to that from various monkey species in Kibale, Uganda, and baboons from Tanzania and South Africa; another was shared by a baboon from Tanzania. No genotype was identical with that of the cryptic species reported from humans and monkeys in Kibale. Phylogeny based on Cox1 sequences of O. stephanostomum showed locality-dependent clades, whereas those of O. bifurcum formed clades composed of worms from different hosts and localities.

Feeding ecology of chimpanzees (Pan troglodytes verus) inhabiting a forest-mangrove-savanna-agricultural matrix at Caiquene-Cadique, Cantanhez National Park, Guinea-Bissau

With rising conversion of "natural" habitat to other land use such as agriculture, nonhuman primates are increasingly exploiting areas influenced by people and their activities. Despite the conservation importance of understanding the ways in which primates modify their behavior to human pressures, data are lacking, even for well-studied species. Using systematically collected data (fecal samples, feeding traces, and direct observations), we examined the diet and feeding strategies of an unhabituated chimpanzee community (Pan troglodytes verus) at Caiquene-Cadique in Guinea-Bissau that inhabit a forest-savanna-mangrove-agricultural mosaic. The chimpanzees experienced marked seasonal variations in the availability of plant foods, but maintained a high proportion of ripe fruit in the diet across months. Certain wild species were identified as important to this community including oil-palm (Elaeis guineensis) fruit and flower. Honey was frequently consumed but no other insects or vertebrates were confirmed to be eaten by this community. However, we provide indirect evidence of possible smashing and consumption of giant African snails (Achatina sp.) by chimpanzees at this site. Caiquene-Cadique chimpanzees were confirmed to feed on nine different agricultural crops, which represented 13.6% of all plant species consumed. Consumption of fruit and nonfruit crops was regular, but did not increase during periods of wild fruit scarcity. Crop consumption is an increasing and potentially problematic behavior, which can impact local people's tolerance toward wildlife. To maximize the potential success of any human-wildlife coexistence strategy (e.g., to reduce primate crop feeding), knowledge of primate behavior, as well as multifaceted social dimensions of interactions, is critical.

Leaf swallowing and parasitic infection of the Chinese lesser civet Viverricula indica in northeastern Taiwan

Background

Ingestion of plant parts purportedly for their non-nutritive and/or bioactive properties has been widely reported across the animal kingdom. Many of these examples are viewed as behavioral strategies to maintain health by controlling the level of parasite infections. One such behavior is leaf swallowing, the folding and swallowing of whole leaves without chewing. Void of any nutritional benefit, defecation of the whole leaves is associated with the physical expulsion of intestinal parasites. Fecal samples of the Chinese lesser civet Viverricula indica were collected along a fixed transect line monthly for 17 months in the Fushan Experimental Forest, northeastern Taiwan. We inspected samples for the occurrence of undigested leaves and parasite worms to test the possible antiparasitic function of the behavior in this species.

Results

Of the collected feces, 14.3% contained whole, folded, undigested leaves of grass. The co-occurrence of undigested grass and Toxocara paradoxura worms in the feces was statistically significant. Adult worms of T. paradoxura were trapped inside the fecal-grass mass or on the surface of leaves in these samples. Increases in the T. paradoxura prevalence and infection intensity were associated with a higher presence of whole leaves in the feces.

Conclusions

Reported for the first time in the context of self-medication for civet species, we propose that swallowing grass may facilitate expulsion of adult worms of T. paradoxura, which resembles behaviors widely reported in African great apes, bears, and geese.

New evidence for self-medication in bonobos: Manniophyton fulvum leaf- and stemstrip-swallowing from LuiKotale, Salonga National Park, DR Congo

The swallowing of entire leaves by apes across Africa without chewing has been observed for over 40 plant species. Here we add evidence for (a) a new site, LuiKotale where leaf-swallowing of Manniophyton fulvum (Euphorbiaceae) is observed in bonobos, (b) a so far unreported ingestion of unchewed stemstrips of M. fulvum, we name stemstrip-swallowing; and (c) a test of some of the requirements put forward by Huffman for the assessment of plants ingested for medical purpose. As ecological correlates we analyzed M. fulvum phenological data and examined 1,094 dung piles collected between 2002 and 2009. By that we assessed availability and choice of leaves. In addition, we provide the first full description of the behavior related to this plant species' use by chimpanzees or bonobos using 56 bouts of M. fulvum ingestion observed between October 2007 and February 2010. With these data we tested and met 4 of the 6 requirements given by Huffman, supporting ingestion of this species as self-medication. Despite species' year-round availability and abundance, M. fulvum was ingested only at specific times, in very small amounts, and by a small proportion of individuals per party. In the absence of our own parasitological data, we used M. fulvum swallowing as evidence for parasite infestation, and seasonality as a proxy for stressors underlying seasonal fluctuation and impacting immune responses. Using these indirect factors available, we investigated conditions for a parasite to develop to its infective stage as well as conditions for the host to cope with infections. Both rain and temperature were good predictors for M. fulvum ingestion. We discuss the use of M. fulvum with respect to its hispidity and subsequent purging properties and provide insight into its ethnomedicinal uses by humans, stimulating speculations about potentially additional pharmacological effects.

Does confirmed pathogen transfer between sanctuary workers and great apes mean that reintroduction should not occur? Commentary on "Drug-resistant human Staphylococcus aureus findings in sanctuary apes and its threat to wild ape populations"

This commentary discusses the findings and conclusions of the paper "Drug resistant human Staphylococcus aureus findings in sanctuary apes and its threat to wild ape populations." This paper confirms the zoonotic transfer of Staphylococcus aureus in a sanctuary setting. The assertion that this in itself is enough to reconsider the conservation potential of ape reintroduction provides an opportunity to discuss risk analysis of pathogen transmission, following IUCN guidelines, using S. aureus as an example. It is concluded that ape reintroduction projects must have disease risk mitigation strategies that include effective biosecurity protocols and pathogen surveillance. These strategies will assist with creating a well planned and executed reintroduction. This provides one way to enforce habitat protection, to minimise human encroachment and the risks from the illegal wildlife trade. Thus reintroduction must remain a useful tool in the conservation toolbox.