Novel insight into the genetic diversity of strongylid nematodes infecting South-East and East Asian primates.

With many non-human primates (NHPs) showing continued population decline, there is an ongoing need to better understand their ecology and conservation threats. One such threat is the risk of disease, with various bacterial, viral and parasitic infections previously reported to have damaging consequences for NHP hosts. Strongylid nematodes are one of the most commonly reported parasitic infections in NHPs. Current knowledge of NHP strongylid infections is restricted by their typical occurrence as mixed infections of multiple genera, which are indistinguishable through traditional microscopic approaches. Here, modern metagenomics approaches were applied for insight into the genetic diversity of strongylid infections in South-East and East Asian NHPs. We hypothesized that strongylid nematodes occur in mixed communities of multiple taxa, dominated by Oesophagostomum, matching previous findings using single-specimen genetics. Utilizing the Illumina MiSeq platform, ITS-2 strongylid metabarcoding was applied to 90 samples from various wild NHPs occurring in Malaysian Borneo and Japan. A clear dominance of Oesophagostomum aculeatum was found, with almost all sequences assigned to this species. This study suggests that strongylid communities of Asian NHPs may be less species-rich than those in African NHPs, where multi-genera communities are reported. Such knowledge contributes baseline data, assisting with ongoing monitoring of health threats to NHPs.

Detection of DNA of filariae closely related to Mansonella perstans in faecal samples from wild non-human primates from Cameroon and Gabon.

BACKGROUND: The Onchocercidae is a family of filarial nematodes with several species of medical or veterinary importance. Microfilariae are found in the blood and/or the dermis and are usually diagnosed in humans by microscopy examination of a blood sample or skin biopsy. The main objectives of this study were to evaluate whether filariae DNA can be detected in faecal samples of wild non-human primates (NHPs), whether the detected parasites were closely related to those infecting humans and whether filarial DNA detection in faeces is associated with co-infections with nematodes (Oesophagostumum sp. and Necator sp.) known to cause blood loss while feeding on the host intestinal mucosa. METHODS: A total of 315 faecal samples from 6 species of NHPs from Cameroon and Gabon were analysed. PCRs targeted DNA fragments of cox1 and 12S rDNA genes, to detect the presence of filariae, and the internal transcribed spacer 2 (ITS2), to detect the presence of Oesophagostomum sp. and Necator sp. infections. RESULTS: Among the 315 samples analysed, 121 produced sequences with > 90% homology with Onchocercidae reference sequences. However, 63% of the 12S rDNA and 78% of the cox1 gene sequences were exploitable for phylogenetic analyses and the amplification of the 12S rDNA gene showed less discriminating power than the amplification of the cox1 fragment. Phylogenetic analyses showed that the cox1 sequences obtained from five chimpanzee DNA faecal samples from Gabon and two from Cameroon cluster together with Mansonella perstans with high bootstrap support. Most of the remaining sequences clustered together within the genus Mansonella, but the species could not be resolved. Among the NHP species investigated, a significant association between filarial DNA detection and Oesophagostomum sp. and Necator sp. infection was observed only in gorillas. CONCLUSIONS: To our knowledge, this is the first study reporting DNA from Mansonella spp. in faecal samples. Our results raise questions about the diversity and abundance of these parasites in wildlife, their role as sylvatic reservoirs and their potential for zoonotic transmission. Future studies should focus on detecting variants circulating in both human and NHPs, and improve the molecular information to resolve or support taxonomy classification based on morphological descriptions.

Chabaudstrongylus ninhae (Trichostrongylidae: Cooperiinae) and Oesophagostomum muntiacum (Chabertiidae: Oesophagostominae) in feral alien Reeves's muntjacs on Izu-Oshima Island, Tokyo, Japan.

The naturalization of alien Reeves's muntjacs (Muntiacus reevesi) on Izu-Oshima Island, Tokyo, Japan, has proceeded intensively over the last five decades. To clarify whether the gastrointestinal helminths of these animals were brought from their original endemic area or were newly acquired in Japan, 32 Reeves's muntjacs trapped on the island were parasitologically examined. In addition to Gongylonema pulchrum in the oesophagus (34.4% prevalence), Chabaudstrongylus ninhae (Drózdz, 1967) (Trichostrongylidae: Cooperiinae) and Oesophagostomum muntiacum Jian, 1989 (Chabertiidae: Oesophagostominae) were prevalent in the small (28.1%) and large (46.9%) intestines, respectively. For the first time, these trichostrongylid or chabertiid worms were genetically characterized based on partial nucleotide sequences of the nuclear ribosomal RNA gene (rDNA) and mitochondrial DNA cytochrome c oxidase subunit 1 gene (cox-1), and the phylogenetic relationships with other members of their family were explored. Since these two intestinal nematode species are inherent in muntjacs, this study demonstrates a new distribution of exotic helminth species in Japan in accordance with the naturalization of alien mammalian hosts. The molecular genetic data collected here could assist the taxonomic assessment of morphological variants in different Muntiacus spp. and/or of different geographical origins. Furthermore, our data may help to define the phylogenetic relationships among such isolates.

Diversity and prevalence of gastrointestinal parasites in two wild Galago species in Gabon.

In this study, we characterize the diversity and estimated infection levels of gastrointestinal parasites circulating in two galago species, Galago demidoff and G. thomasi in two sites situated in the Southeastern forests of Gabon. Our study reveals that eleven parasites including nine helminthes (Ascaris spp., Ankylostoma spp., Dicrocoelium spp., Gongylonema spp., Oesophagostomum spp., Lemuricola spp., Strongyloides spp. Trichostrongylus spp. and Trichuris spp.) and two protozoans (Balantidium spp. and Entamoeba spp.) may infect Galago spp. with high infection rates. The results show that: a very similar parasite spectrum is found in both host species; all the taxa identified were previously observed in other Primate species and/or Man. They also show that age, gender and forest type may influence infection rates and/or parasite diversity found in a particular host and/or geographic area.

Prevalence of three Oesophagostomum spp. from Tibetan Pigs analyzed by Genetic Markers of nad1, cox3 and ITS1.

Parasitic nematodes of Oesophagostomum spp., commonly known as 'nodular worms' are one of the most widely distributed and prevalent emerging zoonotic nematodes. However, little is known about the prevalence and gene characteristics of those parasites in Tibetan pigs. Therefore, a study was carried out to investigate the prevalence, isolation and identification of Oesophagostomum spp from Tibetan pigs by genetic markers of nad1,cox3 and ITS1 for the first time. The results revealed that the infection rate of O. dentatum and O. quadrispinulatum by genetic markers of nad1 was 81.13%; 35 (66.04%); the O. dentatum and O. quadrispinulatum by genetic markers cox3 was 66.04%, and O. dentatum and O. stephanostomum by genetic markers ITS1 was found to be 77.36%. Interestingly, the O. stephanostomum specie was identified and isolated from 90.48% stomach and 69.23% colon samples by genetic markers of ITS1. The present study, for the first time has described the presence and genetic characterization of Oesophagostomun spp of O. dentatum, O. quadrispinulatum and especially O. stephanostomum in Tibetan pigs from the high and remote Tibetan plateau. A public concern should be raised in terms of economical losses and severe public health problem.

Sequence variation in two mitochondrial DNA regions and internal transcribed spacer among isolates of the nematode Oesophagostomum asperum originating from goats in Hunan Province, China.

The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5-72% for pcox1, 73.7-74.2% for pnad1 and 58-58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0-1.6% for pcox1, 0-1.9% for pnad1 and 0-1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1-12.5%, 13.3-17.7% and 8.5-18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum.

Molecular identification of the strongyloid nematode Oesophagostomum aculeatum in the Asian wild elephant Elephas maximus.

The transmission of zoonoses by wildlife, including elephants, is a growing global concern. In this study, we screened for helminth infections among Asian wild elephants (Elephas maximus) of the Salakpra Wildlife Sanctuary, Kanchanaburi, Thailand. Elephant faecal samples (45) were collected from the sanctuary grounds during January through November 2013 and assayed individually using the tetranucleotide microsatellite technique. Microscopic examination indicated a high prevalence of strongylids (93.0%) and low prevalences of trichurids (2.3%) and ascarids (2.3%). To identify the strongylid species, small subunit (SSU) rDNA sequences were amplified from copro-DNA and compared with sequences in GenBank. The generated SSU-rDNA sequences comprised five distinct haplotypes that were closely related to Oesophagostomum aculeatum. A phylogenetic analysis that incorporated related nematodes yielded a tree separated into two main clades, one containing our samples and human and domestic animal hookworms and the other consisting of Strongyloides. The present results indicate that O. aculeatum in local elephants is a potential source of helminthiasis in human and domestic animals in this wild-elephant irrupted area.

Nodular Worm Infections in Wild Non-human Primates and Humans Living in the Sebitoli Area (Kibale National Park, Uganda): Do High Spatial Proximity Favor Zoonotic Transmission?

BACKGROUND: Nodular Oesophagostomum genus nematodes are a major public health concern in some African regions because they can be lethal to humans. Their relatively high prevalence in people has been described in Uganda recently. While non-human primates also harbor Oesophagostomum spp., the epidemiology of this oesophagostomosis and the role of these animals as reservoirs of the infection in Eastern Africa are not yet well documented. METHODOLOGY/PRINCIPAL FINDINGS: The present study aimed to investigate Oesophagostomum infection in terms of parasite species diversity, prevalence and load in three non-human primates (Pan troglodytes, Papio anubis, Colobus guereza) and humans living in close proximity in a forested area of Sebitoli, Kibale National Park (KNP), Uganda. The molecular phylogenetic analyses provided the first evidence that humans living in the Sebitoli area harbored O. stephanostomum, a common species in free-ranging chimpanzees. Chimpanzees were also infected by O. bifurcum, a common species described in human populations throughout Africa. The recently described Oesophagostomum sp. found in colobine monkeys and humans and which was absent from baboons in the neighboring site of Kanyawara in KNP (10 km from Sebitoli), was only found in baboons. Microscopic analyses revealed that the infection prevalence and parasite load in chimpanzees were significantly lower in Kanyawara than in Sebitoli, an area more impacted by human activities at its borders. CONCLUSIONS/SIGNIFICANCE: Three different Oesophagostomum species circulate in humans and non-human primates in the Sebitoli area and our results confirm the presence of a new genotype of Oesophagostomum recently described in Uganda. The high spatiotemporal overlap between humans and chimpanzees in the studied area coupled with the high infection prevalence among chimpanzees represent factors that could increase the risk of transmission for O. stephanostomum between the two primate species. Finally, the importance of local-scale research for zoonosis risk management is important because environmental disturbance and species contact can differ, leading to different parasitological profiles between sites that are close together within the same forest patches.

Nodule worm infection in humans and wild primates in Uganda: cryptic species in a newly identified region of human transmission.

INTRODUCTION: Soil-transmitted helminths (STHs) are a major health concern in tropical and sub-tropical countries. Oesophagostomum infection is considered endemic to West Africa but has also been identified in Uganda, East Africa, among primates (including humans). However, the taxonomy and ecology of Oesophagostomum in Uganda have not been studied, except for in chimpanzees (Pan troglodytes), which are infected by both O. bifurcum and O. stephanostomum. METHODS AND FINDINGS: We studied Oesophagostomum in Uganda in a community of non-human primates that live in close proximity to humans. Prevalence estimates based on microscopy were lower than those based on polymerase chain reaction (PCR), indicating greater sensitivity of PCR. Prevalence varied among host species, with humans and red colobus (Procolobus rufomitratus) infected at lowest prevalence (25% and 41% by PCR, respectively), and chimpanzees, olive baboons (Papio anubis), and l'hoest monkeys (Cercopithecus lhoesti) infected at highest prevalence (100% by PCR in all three species). Phylogenetic regression showed that primates travelling further and in smaller groups are at greatest risk of infection. Molecular phylogenetic analyses revealed three cryptic clades of Oesophagostomum that were not distinguishable based on morphological characteristics of their eggs. Of these, the clade with the greatest host range had not previously been described genetically. This novel clade infects humans, as well as five other species of primates. CONCLUSIONS: Multiple cryptic forms of Oesophagostomum circulate in the people and primates of western Uganda, and parasite clades differ in host range and cross-species transmission potential. Our results expand knowledge about human Oesophagostomum infection beyond the West African countries of Togo and Ghana, where the parasite is a known public health concern. Oesophagostomum infection in humans may be common throughout Sub-Saharan Africa, and the transmission of this neglected STH among primates, including zoonotic transmission, may vary among host communities depending on their location and ecology.

Characterization of Oesophagostomum asperum and O. columbianum by internal transcribed spacers of nuclear ribosomal DNA.

In the present study, the internal transcribed spacers (ITS) of ribosomal DNA (rDNA) of Oesophagostomum asperum and O. columbianum were amplified and sequenced. The ITS-1, 5.8S and ITS-2 rDNA sequences of O. asperum were 374 bp, 153 bp and 259 bp in length, respectively, and the corresponding sequences of O. columbianum were 259, 153 and 218 bp in length, respectively. Sequence differences in the ITS-1 and ITS-2 rDNA between the two Oesophagostomum species were 9.5-10.2% and 12.7-13.9%, respectively. Sequence differences in the ITS-1 and ITS-2 rDNA among members of the genus Oesophagostomum were 2.5-11.6% and 6.8-22.3%, respectively. Based on genetic markers in the ITS rDNA, an effective polymerase chain reaction (PCR) approach was developed to differentiate O. columbianum from O. asperum with a sensitivity of 0.2 ng/µl DNA. Since accurate characterization of parasites at different taxonomic levels is essential for population genetic studies and control of parasitosis, the present findings have important implications for studying epidemiology, taxonomy and population biology, as well as for the control of oesophagostomiasis.

Morphological identification of parasitic nematode infective larvae of small ruminants and cattle: a practical lab guide.

In 2004, a new concept was introduced for simplifying identification of larvae of the common nematodes of cattle, sheep and goats that comprises estimates of the lengths of the sheath tail extensions of infective third-stage larvae (L3) of each genus and/or species to that of Trichostrongylus spp., instead of having to be dependent only on measurements in micrometre. For example, if the mean length of the sheath tail extension (the extension of the sheath caudad, beyond the caudal tip of the larva) of Trichostrongylus colubriformis and Trichostrongylus axei is assumed to be 'X', then that of Haemonchus contortus is 2.0-2.7 'X' - a difference that is not difficult to estimate. An additional new approach suggested now, particularly for L3 of species and/or genera difficult to differentiate (such as Chabertia ovina and Oesophagostomum columbianum), is to estimate the proportion of the larval sheath tail extension comprising a terminal thin, whip-like filament. For the experienced person, it is seldom necessary to measure more than one or two sheath tail extensions of L3 in a mixed culture, because the identity of most of the remaining L3 can thereafter be estimated in relation to those measured, without having to take further measurements. The aim of this article was to present the novel approach in the form of a working guide for routine use in the laboratory. To facilitate identification, figures and a separate organogram for each of small ruminants and cattle have been added to illustrate the distinguishing features of the common L3.

Molecular identification of Oesophagostomum and Trichuris eggs isolated from wild Japanese macaques.

Natural habitat fragmentation and reducing habitat quality have resulted in an increased appearance of Japanese macaques, Macaca fuscata (Gray, 1870), in suburban areas in Japan. To investigate the risk of zoonotic infections, a coprological survey of helminth eggs passed by wild Japanese macaques was carried out in 2009 and 2010 in Shiga Prefecture, Japan. Microscopic examination found helminth eggs in high prevalence, and nucleotide sequencing of DNA extracted from the eggs identified Oesophagostomum cf. aculeatum and Trichuris trichiura. A fecal culture also detected infective larvae of Strongyloides fuelleborni. These zoonotic nematodes pose a potential health issue to local people in areas frequented by Japanese macaques.

Oesophagostomum dentatum and Oesophagostomum quadrispinulatum: characterization of the complete mitochondrial genome sequences of the two pig nodule worms.

In the present study, the complete mitochondrial DNA (mtDNA) sequences of the pig nodule worm Oesophagostomum quadrispinulatum were determined for the first time, and the mt genome of Oesophagostomum dentatum from China was also sequenced for comparative analysis of their gene contents and genome organizations. The mtDNA sequences of O. dentatum China isolate and O. quadrispinulatum were 13,752 and 13,681 bp in size, respectively. Each of the two mt genomes comprises 36 genes, including 12 protein-coding genes, two ribosomal RNA and 22 transfer RNA genes, but lacks the ATP synthetase subunit 8 gene. All genes are transcribed in the same direction and have a nucleotide composition high in A and T. The contents of A+T are 75.79% and 77.52% for the mt genomes of O. dentatum and O. quadrispinulatum, respectively. Phylogenetic analyses using concatenated amino acid sequences of the 12 protein-coding genes, with three different computational algorithms (maximum likelihood, maximum parsimony and Bayesian inference), all revealed that O. dentatum and O. quadrispinulatum represent distinct but closely-related species. These data provide novel and useful markers for studying the systematics, population genetics and molecular diagnosis of the two pig nodule worms.

Some aspects of nematode infection in pigs from small herds.

Two traditionally maintained, small herds from southern Poland, with 8 and 12 sows, respectively, were surveyed coprologically during 2006-2007. In one of the herds, while deworming a group of sows with levamisole, faecal samples were collected on Day -7, Day 0 (the day of treatment) and Day 10, in order to assess the therapeutic effect of the drug. Coprological investigation was performed also in 26 fatteners originating from other small farms and slaughtered in a local abattoir, with their intestines washed through for the presence of roundworms. In both herds examined, Ascaris suum and Oesophagostomum spp. were prevalent, whilst Trichuris suis appeared only very rarely. Mainly fatteners, replacement gilts and young sows were highly infected with A. suum. The roundworm occurrence in 2- 3-week-old piglets, with the intensity of 300 eggs per gram of faeces (EPG), indicated the possibility of parasite transmission to offspring very early in age. The highest level of Oesophagostomum spp. infection was observed in sows, but weaners were also much affected. For the group of dewormed sows, the mean faecal egg count reduction (FECR) was estimated to be 77.1- 80.4%, suggesting the presence of resistant nodular worms. A very high false-positive A. suum egg counts found in slaughtered animals (240 to 320 EPG) testified to a high contamination level of the environment of small piggeries, as well. Since the reciprocal transmission of parasites between pigs and poultry might occur, it implies that the flocks should be raised separately.

A multiplex PCR tool for the specific identification of Oesophagostomum spp. from pigs.

Based on the sequences of the internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal deoxyribonucleic acid (DNA) of the porcine nodule worms Oesophagostomum dentatum and O. quadrispinulatum, a pair of specific primers (OdspF/OdspR2) for O. dentatum and a pair of specific primers (OqspF/OqspR) for O. quadrispinulatum were designed and used to develop a multiplex polymerase chain reaction (PCR) assay for the identification and differentiation of the two porcine nodule worms. This approach allowed the specific identification and differentiation of O. dentatum and O. quadrispinulatum, with no amplicons being amplified from heterogeneous DNA samples, and sequencing confirmed the identity of the sequences amplified. The minimum amount of DNA detectable using this multiplex PCR assay was 0.1 ng for both O. dentatum and O. quadrispinulatum. The identity of 53 porcine nodule worms collected from pigs from different geographical localities in mainland China was ascertained as O. dentatum or O. quadrispinulatum, respectively, by this multiplex PCR method. This multiplex PCR assay is useful for the simultaneous identification of eggs of O. dentatum and O. quadrispinulatum and should provide a useful tool for the diagnosis and molecular epidemiological investigation of Oesophagostomum spp. infection in pigs.

[Oesophagostomum quadrispinulatum (Marcone, 1901) Alicata, 1935--a new for Poland parasite of swine]. / Oesophagostomum quadrispinulatum (Marcone, 1901) Alicata, 1935--nowy dla Polski pasoiyt swin.

MATERIAL AND METHODS: Large intestines of five slaughtered sows, aging 10 months to 3 years and originating from different herds of southern Poland, were examined parasitologically according to an agar-gel method. The intestines were uncoiled and divided into three sections: section 1--caecum and the first 0-20% part of colon, section 2-20--60% of large intestine and section 3--60-100% length of gut. Adult worms of Oesophagostomum were differentiated on the basis of species and sex, using the shape of buccal capsule and oesophagus, the length of male spicules, and the distance from vulva to anus as well as from anus to the tip of tail of females. RESULTS: In the case of two sows, in 30% of the contents from the section 1 of large intestines a total of 10 specimens of Oesophagostomum quadrispinulatum (Marcone, 1901) Alicata, 1935 were found. This is a new nematode species in the parasitic fauna of Poland and the present record enlarges its geographical range. The infection with O. quadrispinulatum seems to be more dangerous from that of O. dentatum--the most common porcine nodular worm.

Characterization of Oesophagostomum spp. from pigs in China by PCR-based approaches using genetic markers in the internal transcribed spacers of ribosomal DNA.

In the present study, samples of Oesophagostomum spp. collected from pigs from different geographical localities in mainland China were characterized genetically by polymerase chain reaction-linked single-strand conformation polymorphism (PCR-SSCP) and restriction fragment length polymorphism (PCR-RFLP) techniques using genetic markers in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (rDNA). The second internal transcribed spacer (ITS-2) was amplified from 51 individual nodule worms by PCR, and the amplicons were analyzed by SSCP. With the exception of slight microheterogeneity, SSCP analyses displayed two distinct banding profiles that allowed the identification of all Oesophagostomum spp. samples examined into two groups, the first one represented O. dentatum, and the second one may represent O. quadrispinulatum. Then, the entire ITS was amplified from individual samples, and the amplicons were digested with restriction endonuclease Pst I. The results of RFLP analyses were consistent with that of SSCP. Sequence analysis of ITS rDNA supported the identification and differentiation of Chinese Oesophagostomum spp. samples into two species, namely, O. dentatum and O. quadrispinulatum. These PCR-based approaches provide useful complementary tools to traditional methods for the accurate identification of Oesophagostomum spp. (irrespective of developmental stage) and have implications for studying the ecology and population genetic structures of these parasites and for the prevention and control of the diseases they cause.

Insights into the epidemiology and genetic make-up of Oesophagostomum bifurcum from human and non-human primates using molecular tools.

The nodule worm Oesophagostomum bifurcum (Nematoda: Strongylida) is a parasite of major human health importance predominantly in northern Togo and Ghana. Currently, it is estimated that 0.25 million people are infected with this nematode, and at least 1 million people are at risk of infection. Infection with this parasite causes significant disease as a consequence of encysted larvae in the wall of the large intestine. In spite of the health problems caused by O. bifurcum, there have been significant gaps in the knowledge of the biology, transmission and population genetics of the parasite. This review provides an account of some recent insights into the epidemiology and genetics of the parasite from human and non-human primate hosts in specific regions of Africa using molecular tools. Recent research findings are discussed mainly in relation to non-human primates being reservoirs of infection, and the consequences for the prevention and control of oesophagostomiasis in humans are briefly discussed.

Definition of genetic markers in nuclear ribosomal DNA for a neglected parasite of primates, Ternidens deminutus (Nematoda: Strongylida)--diagnostic and epidemiological implications.

Ternidens deminutus (Strongylida) is a parasitic nematode infecting non-human and human primates in parts of Africa, Asia and the Pacific islands. The present study genetically characterized T. deminutus and defined genetic markers in nuclear ribosomal DNA (rDNA) as a basis for developing molecular-diagnostic tools. The sequences of the second internal transcribed spacer (ITS-2) of rDNA were determined for adult specimens of T. deminutus (Nematoda: Strongylida: Oesophagostominae) from the Olive baboon and the Mona monkey. The length and G+C content of the ITS-2 sequences was 216 bp and approximately 43%, respectively. While there was no sequence variation among individual T. deminutus specimens from the baboon, 6 (2.8%) nucleotide differences were detected in the ITS-2 between the parasite from baboon and that of the Mona monkey, which is similar to the difference (3.2%) between 2 other species of Oesophagostominae (Oesophagostomum bifurcum and O. stephanostomum) from non-human primates, suggesting significant population variation or the existence of cryptic (i.e. hidden) species within T. deminutus . Pairwise comparisons of the ITS-2 sequences of the 2 operational taxonomic units of T. deminutus with previously published ITS-2 sequences for selected members of the subfamilies Oesophagostominae and Chabertiinae indicated that species from primates (including those representing the subgenera Conoweberia and Ihleia) are closely related, in accordance with previous morphological studies. The sequence differences (27-48.3%) in the ITS-2 between the 2 taxonomic units of T. deminutus and hookworms (superfamily Ancylostomatoidea) enabled their identification and delineation by polymerase chain reaction (PCR)-based mutation scanning. The genetic markers in the ITS-2 provide a foundation for improved, PCR-based diagnosis of T. deminutus infections and for investigating the life-cycle, transmission patterns and ecology of this parasite.

Genetic substructuring within Oesophagostomum bifurcum (Nematoda) from human and non-human primates from Ghana based on random amplified polymorphic DNA analysis.

Random amplified polymorphic DNA (RAPD) was used to study genetic variation within Oesophagostomum bifurcum in Ghana. Four different decamer primers were used for the amplification of DNA from individual O. bifurcum adults (n = 41) from humans and non-human primates (including the Mona monkey, Patas monkey and Olive baboon) from different geographic regions. Analysis of the amplicons from all 41 nematodes by high resolution, denaturing polyacrylamide gel electrophoresis defined a total of 326 informative RAPD bands. Cluster analysis of the RAPD data (based on pairwise comparison of banding profiles) showed that O. bifurcum from humans was genetically distinct from O. bifurcum from the Mona and Patas monkeys, and from the Olive baboon. These findings clearly demonstrate the existence of population genetic substructuring within O. bifurcum from different primate hosts in Ghana, and raise interesting questions about host specificity, epidemiology (e.g., zoonotic transmission), and ecology of the different genotypes of O. bifurcum.