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.

Correction to: Do habituation, host traits and seasonality have an impact on protist and helminth infections of wild western lowland gorillas?

Affiliation of Klára J. Petrzelková was incorrectly assigned as 2, 9, 10 in the original version of this article when in fact it should have been 3, 9, 10. Correct affiliations are presented here.

Do habituation, host traits and seasonality have an impact on protist and helminth infections of wild western lowland gorillas?

Increased anthropogenic activity can result in parasite exchanges and/or general changes in parasite communities, imposing a health risk to great apes. We studied protist and helminth parasites of wild western lowland gorilla groups in different levels of habituation, alongside humans inhabiting Dzanga-Sangha Protected Areas in the Central African Republic. Faeces were collected yearly during November and December from 2007 to 2010 and monthly from November 2010 to October 2011. Protist and helminth infections were compared among gorilla groups habituated, under habituation and unhabituated, and the effect of host traits and seasonality was evaluated. Zoonotic potential of parasites found in humans was assessed. No significant differences in clinically important parasites among the groups in different stages of habituation were found, except for Entamoeba spp. However, humans were infected with four taxa which may overlap with taxa found in gorillas. Females were less infected with spirurids, and adults had higher intensities of infection of Mammomonogamus sp. We found seasonal differences in the prevalence of several parasite taxa, but most importantly, the intensity of infection of unidentified strongylids was higher in the dry season. This study highlights that habituation may not necessarily pose a greater risk of protist and helminth infections in gorilla groups.

Humans and great apes cohabiting the forest ecosystem in central african republic harbour the same hookworms.

BACKGROUND: Hookworms are important pathogens of humans. To date, Necator americanus is the sole, known species of the genus Necator infecting humans. In contrast, several Necator species have been described in African great apes and other primates. It has not yet been determined whether primate-originating Necator species are also parasitic in humans. METHODOLOGY/PRINCIPAL FINDINGS: The infective larvae of Necator spp. were developed using modified Harada-Mori filter-paper cultures from faeces of humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. The first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA and partial cytochrome c oxidase subunit 1 (cox1) gene of mtDNA obtained from the hookworm larvae were sequenced and compared. Three sequence types (I-III) were recognized in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A-C). The combinations determined were I-A, II-B, II-C, III-B and III-C. Combination I-A, corresponding to N. americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans, western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%. CONCLUSIONS/SIGNIFICANCE: The distinctness of ITS sequence variants and high number of pairwise nucleotide differences among cox1 variants indicate the possible presence of several species of Necator in both humans and great apes. We conclude that Necator hookworms are shared by humans and great apes co-habiting the same tropical forest ecosystems.

Gastrointestinal symbionts of chimpanzees in Cantanhez National Park, Guinea-Bissau with respect to habitat fragmentation.

One of the major factors threatening chimpanzees (Pan troglodytes verus) in Guinea-Bissau is habitat fragmentation. Such fragmentation may cause changes in symbiont dynamics resulting in increased susceptibility to infection, changes in host specificity and virulence. We monitored gastrointestinal symbiotic fauna of three chimpanzee subpopulations living within Cantanhez National Park (CNP) in Guinea Bissau in the areas with different levels of anthropogenic fragmentation. Using standard coproscopical methods (merthiolate-iodine formalin concentration and Sheather's flotation) we examined 102 fecal samples and identified at least 13 different symbiotic genera (Troglodytella abrassarti, Troglocorys cava, Blastocystis spp., Entamoeba spp., Iodamoeba butschlii, Giardia intestinalis, Chilomastix mesnili, Bertiella sp., Probstmayria gombensis, unidentified strongylids, Strongyloides stercoralis, Strongyloides fuelleborni, and Trichuris sp.). The symbiotic fauna of the CNP chimpanzees is comparable to that reported for other wild chimpanzee populations, although CNP chimpanzees have a higher prevalence of Trichuris sp. Symbiont richness was higher in chimpanzee subpopulations living in fragmented forests compared to the community inhabiting continuous forest area. We reported significantly higher prevalence of G. intestinalis in chimpanzees from fragmented areas, which could be attributed to increased contact with humans and livestock.

Molecular diversity of entodiniomorphid ciliate Troglodytella abrassarti and its coevolution with chimpanzees.

The entodiniomorphid ciliate Troglodytella abrassarti is a colonic mutualist of great apes. Its host specificity makes it a suitable model for studies of primate evolution. We explored molecular diversity of T. abrassarti with regard to large geographical distribution and taxonomic diversity of its most common host, the chimpanzee. We found a very low diversification of T. abrassarti in chimpanzees across Africa. Distribution of two types of T. abrassarti supports evolutionary separation of the Western chimpanzee, P. t. verus, from populations in Central and East Africa. Type I T. abrassarti is probably a derived form, which corresponds with the Central African origin of chimpanzees and a founder event leading to P. t. verus. Exclusivity of the respective types of T. abrassarti to Western and Central/Eastern chimpanzees corroborates the difference found between an introduced population of presumed Western chimpanzees on Rubondo Island and an autochthonous population in mainland Tanzania. The identity of T. abrassarti from Nigerian P. t. ellioti and Central African chimpanzees suggests their close evolutionary relationship. Although this contrasts with published mtDNA data, it corroborates current opinion on the exclusive position of P. t. verus within the chimpanzee phylogeny. The type of T. abrassarti occurring in Central and East African common chimpanzee was confirmed also in bonobos. This may point to the presence of an ancestral Type II found throughout the Lower Guinean rainforest dating back to the common Pan ancestor. Alternatively, the molecular uniformity of T. abrassarti may imply a historical overlap of the species' distribution ranges.

The effect of low- and high-fiber diets on the population of entodiniomorphid ciliates Troglodytella abrassarti in captive chimpanzees (Pan troglodytes).

Troglodytella abrassarti is an intestinal entodiniomorphid ciliate commonly diagnosed in the feces of wild and captive chimpanzees (Pan troglodytes). Entodiniomorphids could be considered to have a mutualistic relationship with the great apes, in that the ciliates benefit from the intestinal ecosystem of the host, while also contributing to the fiber fermentation process. We examined the effect of diet on the infection intensities of T. abrassarti in two captive chimpanzees in the Liberec Zoo, Czech Republic. The chimpanzees were fed a low-fiber diet (LFD) with 14% neutral detergent fiber (NDF) and a high-fiber diet (HFD; 26% NDF) for 10 days with one transition, and two 10-day adaptation periods. Fecal samples were examined coproscopically with the merthiolate-iodine-formaldehyde concentration (MIFC) technique, in order to quantify the number of ciliates per gram of feces. A significant trend of increasing T. abrassarti numbers was observed when the animals were fed the LFD, compared to when they were fed the HFD. Our results suggest, however, that infection intensities of T. abrassarti in captive chimpanzees are not influenced primarily by the amount of fiber in the diet, but rather by the dietary starch concentration (HFD: 1%; LFD: 8%).

Distribution of the entodiniomorphid ciliate Troglocorys cava Tokiwa, Modrý, Ito, Pomajbíková, Petrzelková, & Imai, , (Entodiniomorphida: Blepharocorythidae) in wild and captive chimpanzees.

Trophozoites of Troglocorys cava were detected in all but one of the wild chimpanzee populations from Rubondo Island (Tanzania), with a prevalence ranging between 20% and 78%. However, the ciliate was absent in all captive groups. Prevalence appeared to increase with the number of sequential samples taken from a particular individual and reached 95.5% in wild individuals sampled at least 4 times.

Survival and morphologic changes of entodiniomorphid ciliate Troglodytella abrassarti in chimpanzee feces.

Entodiniomorphid ciliates occur in the hindgut of both captive and wild African great apes. These ciliates do not form cysts, and therefore they are more susceptible for degradation. This present study focused on the survival, quantification, and decomposition processes of Troglodytella abrassarti trophozoites in the feces of captive chimpanzees. Fecal samples were examined using wet mounts and the merthiolate-iodine-formaldehyde concentration method, and the number of ciliates was expressed as ciliates per gram, which did not differ when examined from three different samples of the same feces. Trophozoites of T. abrassarti survived 5-15 hr after defecation at 25 degrees C under aerobic conditions. Decomposition of trophozoites began immediately after defecation; however, most of the trophozoites had a compact shape and visible cilia. Trophozoites, although without cilia, can be detected in the feces 55-65 hr after defecation, although most of the trophozoites were fragmented. The total number of ciliates in the sample started to decrease 35-55 hr after defecation. The absence of entodiniomorphid ciliates in fecal samples could not be caused by delayed feces fixation; instead, the absence was due to low sensitivity of coproscopic techniques. However, because of quick morphologic changes of trophozoites, accurate identification of ciliates in older samples may be difficult or even impossible.

Discrepancies in the occurrence of Balantidium coli between wild and captive African great apes.

Balantidium coli is a ciliate reported in many mammalian species, including African great apes. In the former, asymptomatic infections as well as clinical balantidiasis have been reported in captivity. We carried out a cross-sectional study of B. coli in African great apes (chimpanzees, bonobos, and both species of gorillas) and examined 1,161 fecal samples from 28 captive facilities in Europe, plus 2 sanctuaries and 11 wild sites in Africa. Samples were analyzed with the use of Sheather's flotation and merthiolate-iodine-formaldehyde (MIFC) sedimentation. MIFC sedimentation was the more sensitive technique for diagnostics of B. coli in apes. Although not detected in any wild-ape populations, B. coli was diagnosed in 52.6% of captive individuals. Surprisingly, in the apes' feces, trophozoites of B. coli were commonly detected, in contrast with other animals, e.g., Old World monkeys, pigs, etc. Most likely reservoirs for B. coli in captive apes include synantropic rats. High starch diets in captive apes are likely to exacerbate the occurrence of balantidiasis in captive apes.

A survey of entodiniomorphid ciliates in chimpanzees and bonobos.

Intestinal entodiniomorphid ciliates are commonly diagnosed in the feces of wild apes of the genera Pan and Gorilla. Although some authors previously considered entodiniomorphid ciliates as possible pathogens, a symbiotic function within the intestinal ecosystem and their participation in fiber fermentation has been proposed. Previous studies have suggested that these ciliates gradually disappear under captive conditions. We studied entodiniomorphid ciliates in 23 captive groups of chimpanzees, three groups of captive bonobos and six populations of wild chimpanzees. Fecal samples were examined using Sheather's flotation and Merthiolate-Iodine-Formaldehyde Concentration (MIFC) methods. We quantified the number of ciliates per gram of feces. The MIFC method was more sensitive for ciliate detection than the flotation method. Ciliates of genus Troglodytella were detected in 13 groups of captive chimpanzees, two groups of bonobos and in all wild chimpanzee populations studied. The absence of entodiniomorphids in some captive groups might be because of the extensive administration of chemotherapeutics in the past or a side-effect of the causative or prophylactic administration of antiparasitic or antibiotic drugs. The infection intensities of ciliates in captive chimpanzees were higher than in wild ones. We suppose that the over-supply of starch, typical in captive primate diets, might induce an increase in the number of ciliates. In vitro studies on metabolism and biochemical activities of entodiniomorphids are needed to clarify their role in ape digestion.

The occurrence and ape-to-ape transmission of the entodiniomorphid ciliate Troglodytella abrassarti in captive gorillas.

Entodiniomorphid ciliates are often present in the colons of wild apes. In captive apes the infection tends to gradually disappear, with the exception of Troglodytella abrassarti. We used fecal examinations to screen the gorillas (Gorilla gorilla gorilla) in European (Czech Republic, UK) and Australian Zoos to explore the ape-to-ape transmission pattern of T. abrassarti. Gorillas from two out of three European Zoos were positive for T. abrassarti, while gorillas from the Australian Zoo were negative. We documented a horizontal transmission of T. abrassarti to a non-infected adult gorilla introduced into a Troglodytella-positive group in the Prague Zoo and traced the origin of the ciliate infection to the Paignton Zoo (UK) using serial fecal examinations. During this study, two infant gorillas born in the Prague Zoo (CZ) first became positive for T. abrassarti at the age of 9 mo. Ciliate morphology and the sequencing of the small subunit rRNA gene and the internal transcribed spacer rDNA spacer region revealed that T. abrassarti affects both captive gorillas and chimpanzees. We conclude that zoo transport plays a major role in the distribution of T. abrassarti among captive gorillas.

Effects of high- and low-fiber diets on fecal fermentation and fecal microbial populations of captive chimpanzees.

We examined fiber fermentation capacity of captive chimpanzee fecal microflora from animals (n = 2) eating low-fiber diets (LFDs; 14% neutral detergent fiber (NDF) and 5% of cellulose) and high-fiber diets (HFDs; 26% NDF and 15% of cellulose), using barley grain, meadow hay, wheat straw, and amorphous cellulose as substrates for in vitro gas production of feces. We also examined the effects of LFD or HFD on populations of eubacteria and archaea in chimpanzee feces. Fecal inoculum fermentation from the LFD animals resulted in a higher in vitro dry matter digestibility (IVDMD) and gas production than from the HFD animals. However, there was an interaction between different inocula and substrates on IVDMD, gas and methane production, and hydrogen recovery (P <0.001). On the other hand, HFD inoculum increased the production of total short-chain fatty acids (SCFAs), acetate, and propionate with all tested substrates. The effect of the interaction between the inoculum and substrate on total SCFAs was not observed. Changes in fermentation activities were associated with changes in bacterial populations. DGGE of bacterial DNA revealed shift in population of both archaeal and eubacterial communities. However, a much more complex eubacterial population structure represented by many bands was observed compared with the less variable archaeal population in both diets. Some archaeal bands were related to the uncultured archaea from gastrointestinal tracts of homeothermic animals. Genomic DNA in the dominant eubacterial band in the HFD inoculum was confirmed to be closely related to DNA from Eubacterium biforme. Interestingly, the predominant band in the LFD inoculum represented DNA of probably new or yet-to-be-sequenced species belonging to mycoplasms. Collectively, our results indicated that fecal microbial populations of the captive chimpanzees are not capable of extensive fiber fermentation; however, there was a positive effect of fiber content on SCFA production.