Polymorphism in the Ostertagiinae Lopez-Neyra, 1947 and comments on the systematics of these nematodes

Exchanged communities of abomasal nematodes in cervids with a first report on Mazamastrongylus dagestanica in red deer

Introduction

Among large wild game in Poland, the most numerous cervids are red deer and roe deer. Although these species live free, they should be under veterinary supervision because they can transmit infectious agents and parasites to livestock. The aim of this study was to evaluate the biodiversity of the abomasal nematodes which parasitise cervids and present the visual and dimensional characteristics of their spicules.

Material and Methods

Overall, 2,067 spicules of nematodes derived from nine red deer and five roe deer were measured and microphotographed in order to determine the species. The predominant Spiculopteragia boehmi was additionally confirmed molecularly by PCR. The spicule lengths of the most common species found in both hosts simultaneously were compared.

Results

Fourteen species of abomasal nematode were identified. All examined animals but one were infected. The most prevalent parasites in both host species were S. boehmi and Ostertagia leptospicularis. The alien Ashworthius sidemi was found in both hosts, whereas Haemonchus contortus was identified only in red deer. Mazamastrongylus dagestanica was noted in red deer for the first time. A 262-base-pair nucleotide sequence of S. boehmi was obtained and deposited in GenBank. Significantly longer spicules were found in red deer-derived O. leptospicularis and S. boehmi and shorter structures were seen in A. sidemi.

Conclusion

The widespread exchange of abomasal nematodes between various ruminant species questions the relevance of their division into specialists and generalists.

Non-native Nematode Ashworthius sidemi Currently Dominates the Abomasal Parasite Community of Cervid Hosts in the Czech Republic

Ashworthius sidemi is an abomasal nematode typical for Asiatic cervids such as sambar (Rusa unicolor) or sika deer (Cervus nippon). This non-native parasite was introduced into Europe via sika deer in the late 19th and early 20th centuries. The current dynamic spread of this parasite amongst autochthonous wild cervids occurs independently of human activities, and A. sidemi has a negative impact on the health of wild ruminants and may pose a threat to the conservation of endangered wild ungulates and to livestock. This invasive parasite has been previously detected in the Czech Republic, but more accurate information on A. sidemi is required. Only limited information is generally available on the factors influencing the spread of abomasal nematodes in wild ruminants, so more information is necessary for planning effective strategies of parasite control. We therefore conducted a survey on the abomasal nematodes in cervids in both game reserves and hunting grounds across the Czech Republic, taking into account the hosts (species, age, sex) and environmental factors (monthly average temperature). The abomasa of 104 animals belonging to five cervid species originating from various locations of the country were collected. Data on host (species, sex, and age group) and the monthly average temperature in the region were obtained for each animal. The parasitological analyses indicated that 92% of the abomasa were infected by nematodes. Ashworthius sidemi was the most prevalent (72%) and abundant (80% of the total recovered individuals) nematode species and was detected in all cervid species except white-tailed deer. The intensity of A. sidemi was highest in roe deer (Capreolus capreolus) and fallow deer (Dama dama), but A. sidemi abundance did not depend substantially on the host or environmental factors. In contrast, the abundance of nematodes from the subfamily Ostertagiinae was influenced by the host species and temperature. Parasitic load was significantly higher in roe deer and during the warmer periods of the survey. We also detected another non-native nematode species, Spiculopteragia houdemeri. The results of our study suggest that the non-native nematode A. sidemi is now widespread amongst cervid hosts in the Czech Republic, probably due to the high sensitivity of autochthonous cervids to A. sidemi infections as well as adaptation of this parasite to the current climatic conditions of this country.

Characterizing parasitic nematode faunas in faeces and soil using DNA metabarcoding

Background

Gastrointestinal parasitic nematodes can impact fecundity, development, behaviour, and survival in wild vertebrate populations. Conventional monitoring of gastrointestinal parasitic nematodes in wild populations involves morphological identification of eggs, larvae, and adults from faeces or intestinal samples. Adult worms are typically required for species-level identification, meaning intestinal material from dead animals is needed to characterize the nematode community with high taxonomic resolution. DNA metabarcoding of environmental samples is increasingly used for time- and cost-effective, high-throughput biodiversity monitoring of small-bodied organisms, including parasite communities. Here, we evaluate the potential of DNA metabarcoding of faeces and soil samples for non-invasive monitoring of gastrointestinal parasitic nematode communities in a wild ruminant population.

Methods

Faeces and intestines were collected from a population of wild reindeer, and soil was collected both from areas showing signs of animal congregation, as well as areas with no signs of animal activity. Gastrointestinal parasitic nematode faunas were characterized using traditional morphological methods that involve flotation and sedimentation steps to concentrate nematode biomass, as well as using DNA metabarcoding. DNA metabarcoding was conducted on bulk samples, in addition to samples having undergone sedimentation and flotation treatments.

Results

DNA metabarcoding and morphological approaches were largely congruent, recovering similar nematode faunas from all samples. However, metabarcoding provided higher-resolution taxonomic data than morphological identification in both faeces and soil samples. Although concentration of nematode biomass by sedimentation or flotation prior to DNA metabarcoding reduced non-target amplification and increased the diversity of sequence variants recovered from each sample, the pretreatments did not improve species detection rates in soil and faeces samples.

Conclusions

DNA metabarcoding of bulk faeces samples is a non-invasive, time- and cost-effective method for assessing parasitic nematode populations that provides data with comparable taxonomic resolution to morphological methods that depend on parasitological investigations of dead animals. The successful detection of parasitic gastrointestinal nematodes from soils demonstrates the utility of this approach for mapping distribution and occurrences of the free-living stages of gastrointestinal parasitic nematodes.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04935-8.

Route of administration affects the efficacy of moxidectin against Ostertagiinae nematodes in farmed red deer (Cervus elaphus)

The influence of route of administration on the pharmacokinetics and efficacy of macrocyclic lactone anthelmintics has been a subject of interest due to its potential to influence the development of anthelmintic resistance. For most parasite species studied so far, oral administration results in the highest concentrations of drug in the parasites and the highest efficacy against resistant genotypes. However, a recent study in cattle measured the highest levels of ivermectin in the abomasal Ostertagia ostertagi following subcutaneous injection, but it was not possible to correlate these elevated levels with efficacy. Therefore, the current study was initiated to determine whether injectable delivery might be optimal for attaining high efficacy against this important group of parasites. Three on-farm trials were conducted to measure the efficacy of moxidectin administered by the oral, injectable, and pour-on routes against Ostertagiinae parasites in farmed red deer. Groups of rising 1-year old stags (red or red-wapiti crossbreds) in the 84-104 kg weight range were randomised on liveweight into treatment groups of 6 (1 farm) or 8 (2 farms). Animals were treated to individual liveweight with moxidectin oral (0.2 mg/kg), injectable (0.2 mg/kg), pour-on (0.5 mg/kg) or remained untreated. Twelve days later all animals were euthanised and abomasa recovered for worm count. Adult worms were counted in a 2% aliquot of abomasal washings, and adult and fourth stage larvae in a 10 % aliquot following mucosal incubation in physiological saline. In addition, blood was collected from the same 5 animals in each of the treatment groups on days 0, 1, 2, 3, 5, 7 and 12 after treatment and moxidectin levels in plasma were determined using a mass spectrometer. The number of Ostertagiinae surviving treatment was significantly different for each of the treatment groups with injectable administration being most effective, oral administration being the next most effective and pour-on administration the least effective. This applied to both adult worms and fourth stage larvae. A similar pattern was seen in the levels of moxidectin in plasma with both the peak value and area under the concentration curve being highest following injectable administration and lowest following pour-on treatment. Although undertaken in a different host species, the results support the proposition that injectable administration of macrocyclic lactone anthelmintics is likely to be optimal for efficacy against Ostertagiinae parasites and potentially useful in slowing the emergence of resistance in these parasites.

Gastrointestinal Helminths of a European Moose Population in Poland

Parasitic infections have a negative impact on the fecundity and survival of wild ruminants, particularly moose; however, despite being more susceptible to parasitic diseases than other wild cervids, they remain poorly examined in this regard. Therefore, the aim of the present study was to identify gastrointestinal and liver helminth species of the moose population in central Europe, assess the factors contributing to infection intensities and examine their impact on moose health. Abomasum, small intestine, caecum and liver samples were collected from 46 moose in Poland and evaluated for helminth parasite fauna and histopathological changes. Additionally, 289 moose fecal samples were analyzed for the presence of eggs, oocysts and larvae of parasites. In total, 19 parasite taxa were identified. The most prevalent were Mazamastrongylus dagestanica and Ostertagia antipini, which are typical nematodes of moose, together with Spiculopteragia boehmi and O. leptospicularis, characteristic also of other cervids. Parasite species diversity and abomasal parasitic infection intensity were higher in adult moose than in yearlings and calves. The numbers of histopathological lesions depended on the intensity of parasitic infections, and were most severe in the livers of moose infected with Parafasciolopsis fasciolaemorpha. The analysis of fecal samples revealed several regional differences in the levels of parasite eggs, oocysts and larvae shedding. Our findings indicate an accumulation of parasite infections over time in moose, which may be related to high environmental parasite pressure, possibly connected with high moose density and the presence of wetlands; they also serve as the most comprehensive study of moose parasites in central Europe to date.

Nematode-induced pathological lesions and alterations of mucin pattern identified in abomasa of wild ruminants

Pathological lesions as well as mucin alterations in abomasa infected by nematodes have been thoroughly studied in livestock, but such data from wild ruminants are limited or completely lacking. Pathological data for Ashworthius sidemi, an invasive nematode are particularly rare. We necropsied the abomasa of 21 wild ruminants belonging to five cervid species and detected mixed nematode infections, dominated by A. sidemi. Samples from both gross lesions and mucous membranes without macroscopically apparent pathological alterations were subjected to standard histological procedures and histochemical staining. Histological examination found chronic abomasitis, manifested by edema, and hyperemia. Various degrees of lymphoplasmacytic infiltration were observed in all samples. Initial fibrosis (8/20, 40%) was detected in samples from both gross lesions and areas without macroscopically visible changes. Tissue from hemorrhagic lesions was superficially eroded. Generalized loss of surface polysaccharides was apparent in all samples. Only residual periodic acid-Schiff and Alcian blue (pH2.5) positivity was detected in the upper abomasal pits and in mucosal neck. This study found that nematode infections, mostly by A. sidemi, caused chronic inflammation and negatively affected abomasal mucin formation in wild ruminants.

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Histological examination of tissue samples identified nematode-induced abomasitis.

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Loss of superficial polysaccharides was apparent in all tissue samples.

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Mainly acidic residual mucins were detected in abomasal pits and mucosal neck zone.

Morphometric and Molecular Analyses of Ostertagia leptospicularis Assadov, 1953 from Ruminants: Species Diversity or Host Influence?

Simple Summary

Pathogenic nematode Ostertagia leptospicularis, as the sole member of the subfamily Ostertagiinae, occurs in both cervid and bovid host species. The broad host specificity of this parasite draws special attention and requires a more in-depth investigation. This study was carried out to find out whether the differences in the nematode morphology were only due to the host influence, or whether genetic differences should be taken into account. To resolve this issue, the classification of O. leptospicularis was raised and discussed based on its host specificity, as well as morphological and genetic characteristics. A combined morphological–molecular approach was used to compare specimens resembling O. leptospicularis collected from naturally infected hosts of various ruminant species (roe deer, red deer, fallow deer, and cattle). Both morphological and molecular analyses highlighted the distinctiveness of O. leptospicularis collected from cattle in Germany, and therefore should now be considered to be a different strain that those collected form cervids in central Europe.

Abstract

Ostertagia leptospicularis Assadov, 1953 was formally described in roe deer Capreolus capreolus and has been reported in a wide range of ruminants, including other Cervidae, as well as Bovidae. Nematode specimens derived from various host species exhibit morphological similarity; however, some differences can be observed. It is unclear if this is due to the differential reaction of one nematode species in different host species (i.e., host-induced changes) or because of distinct nematode species in these hosts (i.e., species complex). This paper focuses on specimens resembling O. leptospicularis f. leptospicularis and its closely related species (Ostertagia ostertagi f. ostertagi) collected from various hosts. Morphometric and molecular techniques were applied to assess host-induced changes in nematode morphology and to clarify its systematic classification. There was an overall effect of host species on measurements of nematodes resembling O. leptospicularis (both males and females), but the distinctiveness of the specimens from cattle Bos taurus were highlighted. The results obtained may suggest that the specimens of O. leptospicularis from cattle in Germany and cervids in central Europe belong to different strains. Furthermore, nematodes from the cervid strain appear to circulate within particular host species, which can be seen in the stated morphological variations.

Molecular analysis of polymorphic species of the genus Marshallagia (Nematoda: Ostertagiinae)

Background

The genus Marshallagia (Family Haemonchidae, subfamily Ostertagiinae) contains multiple species of nematodes parasitising the abomasum (or duodenum) of ruminants, in particular of Caprinae. Male specimens have been described to be polymorphic with the frequent/major morphotype initially described in the genus Marshallagia while the minor/rare morphotype was initially often placed in the genus Grossospicularia. Due to common morphological features, certain pairs of morphotypes were suggested to belong to the same species such as Marshallagia marshalli/M. occidentalis. However, molecular evidence to confirm these pairs of morphotypes belonging to the same species is missing.

Methods

In the present study, Marshallagia sp. were collected from domestic sheep in Uzbekistan. Male specimens were morphologically described with particular emphasis on the structure of the bursa copulatrix. After DNA isolation from morphologically identified specimens, PCRs targeting the ribosomal internal transcribed spacer 2 (ITS2) and mitochondrial cytochrome c oxidase subunit 1 (cox1) regions were conducted. After Sanger sequencing, maximum likelihood phylogenetic analyses and pairwise identities between sequences were calculated.

Results

The major morphotypes of M. marshalli, M. schumakovitschi and M. uzbekistanica and the minor morphotypes M. occidentalis, M. trifida and M. sogdiana were identified and their morphology was documented in detail. ITS2 sequences showed little variation and did not allow diagnosing species. In contrast, phylogenetic analysis of cox1 sequences identified highly supported clusters and verified that M. marshalli, M. occidentalis and M. uzbekistanica are different morphotypes of the species M. marshalli while M. schumakovitschi and M. trifida represent distinct morphotypes of M. trifida. For M. sogdiana no corresponding major morphotype could be identified in the present study. Due to a large barcoding gap, comparison of cox1 sequences in terms of percent identity was sufficient to reliably assign the sequences to a particular species without phylogenetic analysis.

Conclusions

The data presented here create a framework that will allow the classification of other members of the genus in the future and underline that parallel morphological and molecular analysis of specimens is crucial to improve the taxonomy of polymorphic species.

Gastrointestinal parasites in reindeer (Rangifer tarandus tarandus): A review focusing on Fennoscandia

Reindeer (Rangifer tarandus tarandus) are known to host a wide variety of parasites, including those in the gastrointestinal system. Here, we review the current knowledge of the main gastrointestinal parasites of reindeer focusing on northern Fennoscandia, which comprises parts of Finland, Sweden, Norway and Russia. We explore both the historical baseline data for diversity and distribution and recent advancements in our understanding of parasite faunas in reindeer across this region. It is evident that the balance between reindeer and their gastrointestinal parasites, along with the potential for emergent disease in the changing world warrants careful monitoring and further studies.

Molecular marker sequences of cattle Cooperia species identify Cooperia spatulata as a morphotype of Cooperia punctata

The genus Cooperia includes important parasites of ruminants and currently contains 34 accepted species. However, even for those species infecting livestock, there is a considerable lack of molecular information and many species are only identifiable using subtle morphological traits. The present study aimed to provide molecular data to allow diagnosis of Cooperia species infecting cattle. Partial sequences of two mitochondrial (cytochrome oxidase 2, 12S rRNA gene) and two nuclear genes (isotype 1 β tubulin gene including two introns, internal transcribed spacers (ITS) were obtained from morphologically identified specimens of Cooperia pectinata, Cooperia punctata and Cooperia spatulata as well as from larvae of pure Cooperia oncophora and C. punctata laboratory isolates. Pairwise identity of ITS-2 sequences was very high and it was the only region able to identify a specimen as Cooperia sp. However, the ITS-2 was unreliable for diagnosis at the species level. All other marker sequences could not unequivocally be allocated to the genus Cooperia but allowed clear species identification with the exception of the pair C. punctata/C. spatulata for which no significant differences were found for any marker sequence. Maximum-likelihood phylogenetic analyses of individual genes as well as a multi-locus analysis covering all four sequences confirmed that specimen identified as C. spatulata were randomly distributed throughout the C. punctata cluster and formed no group of their own. In contrast, the other Cooperia species formed clearly separated and statistically supported clusters. These data indicate that C. spatulata is most likely only a morphotype of C. punctata and the name should be considered a synonym. Combinations of nuclear and mitochondrial markers should be used to identify morphotypes or cryptic species to benefit from excellent barcoding properties of the latter but allowing proper phylogenetic analyses and controlling for lineage sorting that might occur for mitochondrial genotypes within a species.

Host specificity and species diversity of the Ostertagiinae Lopez-Neyra, 1947 in ruminants: a European perspective

Background

Nematodes of the subfamily Ostertagiinae appear to be rather specific to a species or family of hosts, but some are observed in a wide variety of hosts. The nematode Ostertagia leptospicularis draws special attention due to its presence or absence among the same host species in different European countries. Therefore, this paper focuses mainly on the host specificity among nematodes of the subfamily Ostertagiinae. The second aim of this study is to assess the possibility of treating O. leptospicularis as an Ostertagia species complex.

Methods

Data were gathered from post-mortem examinations of domestic and wild ruminants (n = 157), as well as bibliographical references (n = 96), which were pooled and discussed. The research area was limited to European countries, hence the studied ostertagiine species are limited to native ones; likewise, the host species. Special emphasis was placed on the mean abundance values that allowed a typical host or hosts for each nematode species to be specified. Correspondence analysis was performed to confirm the stated host specificity.

Results

The analysis revealed that nematodes of this subfamily tend to use ruminants from a particular subfamily as their principal host. The results indicate that Ostertagia leptospicularis, similar to Teladorsagia circumcincta, may represent a potential species complex. This nematode, as the sole member of the subfamily Ostertagiinae, occurs in almost all representatives of the Bovidae subfamily, as well as in the Cervidae.

Conclusions

Despite the stated narrow host specificity, the results obtained may suggest that O. leptospicularis is not strongly connected to any host or is comparably associated with a very wide and diverse group of hosts (Cervidae, Bovidae). The Ostertagia complex may have particular cryptic species or strains typical for any individual host or group of hosts. Such a conclusion requires further investigations on a wider scale.

GASTROINTESTINAL PARASITIC INFECTIONS IN DEAD OR DEBILITATED MOOSE ( ALCES ALCES) IN SWEDEN

:  Our objectives were to determine prevalence and intensity of gastrointestinal parasites of dead or euthanized emaciated moose in central and southern Sweden ( n=50) and to assess parasite intensity as a major contributing factor in the poor condition of these moose. All animals were infected and most had gastrointestinal nematodes. Seven parasite species were found in the abomasa and 10 species were found in the small intestine. Coinfections were commonly found in the abomasum ( Ostertagia antipini and Mazamastrongylus dagestanica) and in the small intestine ( Nematodirella alcidis and Trichostrongylus capricola). Moose had many nematodes; the highest numbers were 224,400 and 11,760, in the abomasum and in the small intestine, respectively. Fourteen moose had more than 40,000 gastrointestinal nematodes (excluding large intestine nematodes represented by Trichuris spp. and Oesophagostomum venulosum). Additionally, a moderate prevalence (36%) of protostrongylid larvae (dorsal spine larvae) and a low prevalence (2-4%) of protozoal infections were identified at microscopic examination of feces. Adult moose had significantly more parasites than did subadults. The results did not show parasite load as a single or a major cause of the moose mortality, but they provided an update on the species composition of helminth parasites in moose in Sweden and illustrated the extreme infection intensities that free-ranging moose can have.

Frequency of gastrointestinal and pulmonary helminth infections in wild deer from western Romania

A survey was carried out to assess the prevalence and the intensity of helminth infections in the roe deer (Capreolus capreolus L.), red deer (Cervus elaphus L.) and fallow deer (Dama dama L.) from 16 hunting areas in western Romania. Overall, 122 deer shot during the hunting season 2013-2015 were examined. Haemonchus contortus, Nematodirus filicollis, Oesophagostomum venulosum and Dictyocalus spp. were found in all the deer species. Trichuris spp. and Dicrocoelium dendriticum were found in the roe deer and red deer and Moniezia expansa in roe deer, only. Overall, the prevalences (<35%) and the mean intensities (<20) were quite low in the abomasums and intestine, but H. contortus in fallow deer (>50%). No >2 or 3 helminth species were found in the abomasum, small and large intestine. Lung helminthes in the roe deer and follow deer accounted for 57.1% and 71.4%, respectively. The only specie with a prevalence >50% was in the red deer. D. dendriticum was found in the liver of roe deer and fallow deer.

Influence of management and biological factors on the parasitic invasions in the wild-spread of blood-sucking nematode Ashworthius sidemi in European bison (Bison bonasus)

The full course of new parasite introductions in wild animals is difficult to accurately trace. We documented and analysed the invasive blood-sucking nematode Ashworthius sidemi (Trichostrongylidae) introduction and spread in European bison (Bison bonasus) from the initial phase of its progression. In the Polish part of the Białowieża Primeval Forest (BPF) the parasite was first found in 2000. From 2002 to 2015, 165 culled bison were investigated. The prevalence and intensity of A. sidemi Schulz, 1933 infection increased over the following years, reaching 100% of investigated bison four years after introduction and a maximal median intensity of 8200 nematodes per animal in the winter of 2008/2009. Afterwards, a significant decline of median infection intensity was observed to the minimum value of 410 nematodes per animal. Between 2011 and 2014 prevalence varied from 89 to 100%. Among the factors analysed, the number of years since introduction, herd size, age and sex proved to significantly influence infection intensity. A higher infection intensity was recorded in sub-adults compared to juveniles and adults. Males had significantly lower infection intensity than females, but this was the case for adults only. The highest infection intensities were recorded in the biggest bison herds, where the winter supplementary feeding of bison is intense. Moreover, the longer the parasite was present in the host population, the more important herd size became as a factor. Our study indicates that it is not solely biological factors that determine the spread of a newly detected parasite in wildlife, but that management practices can also have a strong influence. This is especially important in endangered species under intensive human care as the management practices may pose a threat to the species.

Insight into species diversity of the Trichostrongylidae Leiper, 1912 (Nematoda: Strongylida) in ruminants

This paper focuses on the species diversity among the Trichostrongylidae Leiper, 1912 (Nematoda: Strongylida), and complexity of the family systematics. Polymorphism (subfamilies: Ostertagiinae, Cooperiinae and Haemonchinae), the presence of cryptic species (genus: Teladorsagia) and hybridization (genera: Cooperia, Haemonchus and Ostertagia) are presented and discussed, considering both morphological and molecular evidence. Some of these phenomena are common, nevertheless not sufficiently understood, which indicates the need for expanding the current state of knowledge thereof. Within the Trichostrongylidae, species distinction supported merely by morphological features is difficult, and requires confirmation by means of molecular methods. The parasitic nematode taxonomy is complicated mainly by the genus Teladorsagia, but complexity may also be expected among other Ostertagiinae (e.g. in the genera Ostertagia and Marshallagia). The data presented here show that the members of the Trichostrongylidae can significantly complicate unambiguous species identification. Hence, it is essential to consider the phenomena mentioned, to gather valid and comparable data on the biodiversity of this family.

Species discrimination in the subfamily Ostertagiinae of Northern China: assessment of DNA barcode in a taxonomically challenging group

Gastrointestinal nematodes within the subfamily Ostertagiinae (Teladorsagia, Ostertagia, and Marshallagia et al.) are among the most common infections of domesticated livestock. These parasites are of particular interest, as many of the species within this group are of economic importance worldwide. Traditionally, nematode species designations have been based on morphological criteria. However, this group possesses poorly defined species. There is an urgent need to develop a reliable technique that can distinguish species of Ostertagiinae. DNA barcoding has been proved to be a powerful tool to identify species of birds, mammals, and arthropods, but this technique has not yet been examined for identifying species of Ostertagiinae. In this study, a total of 138 mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI) sequences from individuals representing 11 species of Ostertagiinae were acquired by PCR for the first time. The specimens were collected from pastoral area of northern China. Genetic divergence analyses showed that mean interspecific Kimura two-parameter distances of COI (13.61 %) were about four times higher than the mean value of the intraspecific divergence (3.69 %). Then, the performance of the COI to identify species of Ostertagiinae was evaluated by identification success rates using nearest neighbor (NN) and BLASTn. The results indicated that the rates of correct sequence identification for COI were high (>80 %) when using the NN and BLASTn methods. Besides, the deep lineage divergences are detected in Teladorsagia circumcincta. Meanwhile, the analyses also detected no genetic differentiation between some species such as Ostertagia hahurica and Ostertagia buriatica. These results indicate that the traditional status of species within Ostertagiinae should be closely examined based on the molecular data.

Endoparasites in a Norwegian moose (Alces alces) population - Faunal diversity, abundance and body condition

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Moose in Hedmark have high abomasal parasite burdens.

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11 parasite groups were identified with abomasal GINs found in all individuals.

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4 abomasal GINs identified; Ostertagia antipini and Spiculopteragia alcis dominated.

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Body condition index was negatively related to abomasal parasite burden.

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Fat reserve assessment and faecal egg count were poor indicators of parasitism.

Many health surveillance programs for wild cervids do not include routine parasite screening despite evidence that gastrointestinal parasites can affect wildlife population dynamics by influencing host fecundity and survival. Slaughter weights of moose in some regions of Norway have been decreasing over recent decades but any role of parasites has not yet been considered. We investigated parasite faunal diversity of moose in Hedmark, SE Norway, by faecal analysis and identification of adult abomasal and caecal nematodes during the autumn hunting season. We related parasite prevalence and abundance to estimates of body condition, gender and age. We identified 11 parasite groups. Moose had high abomasal gastrointestinal nematode (GIN) burdens and all individuals were infected. Ostertagia antipini and Spiculopteragia alcis were the most prevalent abomasal GINs identified. O. leptospicularis and Telodorsagia circumcincta were also identified in the abomasa while a range of other GIN and Moniezia sp. eggs, and coccidia, Dictyocaulus sp. and Protostrongylid larvae were found in faeces.

Female moose had higher mean abomasal nematode counts than males, particularly among adults. However, adult males had higher faecal egg counts than adult females which may reflect reduction in faecal volume with concentration of eggs among males during the rut. We found no strong evidence for the development of acquired immunity to abomasal nematodes with age, although there was a higher Protostrongylid and Moniezia infection prevalence in younger animals. High burdens of several parasites were associated with poor body condition in terms of slaughter weight relative to skeletal size but unrelated to visually evaluated fat reserves. Given findings from earlier experimental studies, our results imply sub-clinical effects of GI parasite infection on host condition. Managers should be aware that autumn faecal egg counts and field assessments of fat reserves may not be reliable indicators of parasitism and may underestimate impacts on wildlife populations.

Morphological variability and molecular identification of Uncinaria spp. (Nematoda: Ancylostomatidae) from grizzly and black bears: new species or phenotypic plasticity?

The hookworms Uncinaria rauschi Olsen, 1968 and Uncinaria yukonensis ( Wolfgang, 1956 ) were formally described from grizzly ( Ursus arctos horribilis) and black bears ( Ursus americanus ) of North America. We analyzed the intestinal tracts of 4 grizzly and 9 black bears from Alberta and British Columbia, Canada and isolated Uncinaria specimens with anatomical traits never previously documented. We applied morphological and molecular techniques to investigate the taxonomy and phylogeny of these Uncinaria parasites. The morphological analysis supported polymorphism at the vulvar region for females of both U. rauschi and U. yukonensis. The hypothesis of morphological plasticity for U. rauschi and U. yukonensis was confirmed by genetic analysis of the internal transcribed spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA. Two distinct genotypes were identified, differing at 5 fixed sites for ITS-1 (432 base pairs [bp]) and 7 for ITS-2 (274 bp). Morphometric data for U. rauschi revealed host-related size differences: adult U. rauschi were significantly larger in black bears than in grizzly bears. Interpretation of these results, considering the historical biogeography of North American bears, suggests a relatively recent host-switching event of U. rauschi from black bears to grizzly bears which likely occurred after the end of the Wisconsin glaciation. Phylogenetic maximum parsimony (MP) and maximum likelihood (ML) analyses of the concatenated ITS-1 and ITS-2 datasets strongly supported monophyly of U. rauschi and U. yukonensis and their close relationship with Uncinaria stenocephala (Railliet, 1884), the latter a parasite primarily of canids and felids. Relationships among species within this group, although resolved by ML, were unsupported by MP and bootstrap resampling. The clade of U. rauschi, U. yukonensis, and U. stenocephala was recovered as sister to the clade represented by Uncinaria spp. from otariid pinnipeds. These results support the absence of strict host-parasite co-phylogeny for Uncinaria spp. and their carnivore hosts. Phylogenetic relationships among Uncinaria spp. provided a framework to develop the hypothesis of similar transmission patterns for the closely related U. rauschi, U. yukonensis, and U. stenocephala.

Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus)

Background

Thirteen red deer (Cervus elaphus), culled from the isolated population at the Mongstad Oil Refinery, Norway, were investigated for gastrointestinal helminths. These animals, enclosed by the refinery fence, do not have contact with other ruminants and have a high population density considering the available browsing area (1 km²) within the refinery site (3 km²). The population was estimated to be 110-130 at the time of culling.

Results

The helminth fauna among these sampled red deer was enumerated and species were identified based on morphology. Ostertagia leptospicularis/O. kolchida was detected in 83% [CI 55 - 95%], Spiculopteragia spiculoptera/S. mathevossiani in 92% [CI 65 - 99%] and Trichostrongylus axei in 42%, [CI 19 - 68%] of the abomasa examined. Characterisation of the intestinal parasite fauna revealed Capillaria bovis, Cooperia oncophora, Oesophagostomum venulosum, Trichuris globulosa and tapeworm fragments (presumed anoplocephalids) in seven individuals. Only one calf had an infection with more than one intestinal helminth (tapeworm fragment and Trichuris globulosa). The remaining six deer had single species intestinal infections.

No significant age related trends were seen, with the exception of higher intensity of infection of T. axei in yearlings relative to other age classes. Assessment of abomasal parasite burden and body condition revealed no significant trends. In calves, statistically non-significant correlation was seen between increased parasite burden and decreased slaughter weight, whilst the opposite was seen in adults with the heaviest adults exhibiting the higher burdens. Given the small sample size the trends that were seen need further investigation. The parasite burden was aggregated with three adult red deer harbouring 75% of the total abomasal parasite count.

Conclusion

This isolated population was parasitised by a reduced subset of gastrointestinal nematodes typical of this cervid across an extensive geographic range in Eurasia. The intensity and abundance of abomasal nematodes was higher in this isolated population than reported in similar studies of red deer populations across Europe.

Gastrointestinal nematode infections in roe deer (Capreolus capreolus) from the NW of the Iberian Peninsula: assessment of some risk factors

Intestinal contents of 218 roe deer hunted in the northwest (NW) of the Iberian Peninsula during the 2008-2009 hunting seasons were examined in order to provide information on the gastrointestinal (GI) nematode prevalence and intensity of infection and the possible influence of some environmental and intrinsic factors such as climatic conditions, age and sex. All the animals studied harboured GI nematodes, and a total of 20 different species belonging to ten genera were identified. Spiculopteragia spiculoptera/Spiculopteragia mathevossiani, Ostertagia leptospicularis/Ostertagia kolchida and Nematodirus filicollis were the most common. This is the first citation for Chabertia ovina, Cooperia pectinata, Cooperia punctata, Cooperia oncophora, Haemonchus contortus, Nematodirus spathiger, Oesophagostomum venulosum, Teladorsagia trifurcata, Trichostrongylus capricola, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Trichuris capreoli in roe deer from the Iberian Peninsula. Prevalence and intensity were significantly higher in the abomasum, where infections with more than one GI nematode species were the most common; in the other intestinal segments infections with only one GI nematode species were the most prevalent. When considering the influence of the different risk factors on the prevalence of GI nematodes, the highest prevalence for most of the genera were observed in roe deer from coastal areas, where climatic conditions are more favourable for the development and survival of third stage larvae in the environment. Regarding the sex of the animals, the prevalence was, in general, higher in males than in females, probably due to behavioural and physiological sex-related differences. On the contrary, no differences were found in relation to the age of the animals. This study reveals that roe deer from the NW of the Iberian Peninsula are widely and intensely infected with gastrointestinal nematodes, which probably affect the health status of these ungulates.

Parasites in ungulates of Arctic North America and Greenland: a view of contemporary diversity, ecology, and impact in a world under change

Parasites play an important role in the structure and function of arctic ecosystems, systems that are currently experiencing an unprecedented rate of change due to various anthropogenic perturbations, including climate change. Ungulates such as muskoxen, caribou, moose and Dall's sheep are also important components of northern ecosystems and are a source of food and income, as well as a focus for maintenance of cultural traditions, for northerners. Parasites of ungulates can influence host health, population dynamics and the quality, quantity and safety of meat and other products of animal origin consumed by people. In this article, we provide a contemporary view of the diversity of nematode, cestode, trematode, protozoan and arthropod parasites of ungulates in arctic and subarctic North America and Greenland. We explore the intricate associations among host and parasite assemblages and identify key issues and gaps in knowledge that emerge in a regime of accelerating environmental transition.

Molecular genetic conspecificity of Spiculopteragia houdemeri (Schwartz, 1926) and S. andreevae (Dróżdż, 1965) (Nematoda: Ostertagiinae) from wild ruminants in Japan

Male dimorphism of the subfamily Ostertagiinae (Nematoda: Trichostrongylidae) is a well-known phenomenon, and two or more morphotypes of a single species have previously been described as different species. Two Spiculopteragia spp., S. houdemeri (syn. S. yamashitai) and S. andreevae (syn. Rinadia andreevae) recorded in Asian cervids and wild bovids, are considered to represent major and minor morphs of S. houdemeri, respectively, based solely on their co-occurrence in the same host individual along with monomorphic females. In this study, males of morph houdemeri ( = S. houdemeri) and morph andreevae ( = S. andreevae) as well as females with three different vulval ornamentations were collected from sika deer (Cervus nippon) and Japanese serows (Capricornis crispus) distributed on the mainland of Japan. Morphologically characterized worms were subjected to molecular genetic analyses based on the internal transcribed spacer region of the ribosomal RNA gene and a partial region of the cytochrome c oxidase subunit I gene of mitochondrial DNA. Of 181 collected sika deer, 177 (97.8%) and 73 (40.3%) deer harboured males of morphs houdemeri and andreevae, respectively. Worm numbers of the former morph were found to range between 1 and 444 per individual, whereas only 1–25 worms per individual were detected for the latter morph. Five out of six serows harboured 47–71 or 2–9 males of morphs houdemeri and andreevae per individual, respectively. Females with one or two vulval flaps were predominant, but there was a substantial presence of flapless females in both host species. All the morphs of male and female adults had an identical genetic background, thus directly confirming the morphological polymorphism of S. houdemeri.

Discovery and description of a new trichostrongyloid species (Nematoda: Ostertagiinae), abomasal parasites in mountain goat, Oreamnos americanus, from the Western Cordillera of North America

Marshallagia lichtenfelsi sp. n. is a dimorphic ostertagiine nematode occurring in the abomasum of mountain goats, Oreamnos americanus, from the Western Cordillera of North America. Major and minor morphotype males and females are characterized and distinguished relative to the morphologically similar Marshallagia marshalli / Marshallagia occidentalis from North America and Marshallagia dentispicularis, along with other congeners, from the Palearctic region. The configuration of the convoluted and irregular synlophe in the cervical region of males and females of M. lichtenfelsi is apparently unique, contrasting with a continuous and parallel system of ridges among those species of Marshallagia, including M. marshalli/M. occidentalis, which have been evaluated. Specimens of M. lichtenfelsi are further defined by the rectangular form of the accessory bursal membrane (width > length) in the major morphotype and by the trapezoidal Sjöberg's organ in the minor morphotype, in addition to specific attributes of the spicules and spicule tips. We regard 12 species, including the proposed new taxon, to be valid. Primary diagnostic characters are reviewed for Marshallagia and a framework is presented for standardization of future descriptions incorporating the synlophe in males and females and the structure of the spicules and genital cone in major and minor morphotype males. The center of diversity for species of Marshallagia is the mountain-steppe region of central Eurasia where 11 species (including the Holarctic M. marshalli) are recognized in association with Caprini, Rupicaprini, and Antelopinae; only 2 species occur in the Nearctic. In this assemblage, M. lichtenfelsi is endemic to North America and limited in host distribution to mountain goats. An intricate history for refugial isolation and population fragmentation demonstrated for mountain goats and wild sheep indicates the potential for considerable cryptic diversity for Marshallagia and other nematodes. Shifting patterns of contact and sympatry among assemblages of ungulates during the Pleistocene are consistent with geographic and host colonization as a process involved in diversification of these parasites.

Sex ratio and morphological polymorphism in an isolated, endemicTeladorsagia circumcinctapopulation

Teladorsagia circumcinctais a polygamous nematode that exhibits morphological polymorphism. Sex ratio is typically female biased and the male nematodes occur in association with the genetically similar, minor morphotypesTeladorsagia davtianiandTeladorsagia trifurcata. In experimental infections, sex ratio (proportion male) and the proportion of minor male morphs observed have been shown to be influenced by both host and nematode-related factors. As similar investigations from natural systems are rare, this study examined whether sex ratio and minor male morph frequency were associated with host age and sex and nematode infra-population size in the isolated Soay sheep population on St Kilda. Count data forTeladorsagiawere analysed for sheep of all age classes and both sexes from the winters of three consecutive population crashes (1999, 2002 and 2005). Generally, the intensity ofTeladorsagianematodes increased with host age until the age of 2 years before decreasing. In 2005, abundance of nematodes was generally higher than in the previous crashes, nematode sex ratio was negatively associated with host age and tended to be negatively associated with nematode intensity. Within the male nematode subpopulation,T. circumcinctaalways predominated, followed byT. davtianiand thenT. trifurcata, with little variation in the relative proportions between hosts. The presence of each minor morph was primarily associated with the intensity of maleT. circumcinctaand, in those hosts where all three male morphs were detected, intensity of each minor morph was most associated with intensity ofTeladorsagiafemales. Therefore, in a year when the nematode was generally more abundant, sex ratio appeared to be influenced by both host and nematode-related factors, whereas in all years examined, the frequency of morphological polymorphism was primarily density dependent.

Spiculopteragia mathevossianiRuchliadev, 1948 is the minor morph ofSpiculopteragia spiculoptera(Gushanskaya, 1931): molecular evidence

Although Spiculopteragia spiculoptera is primarily a parasite of cervids, it can also but less often contaminate domestic livestock. Little is known about its epidemiology and its pathogenicity in domestic ruminants and other unusual cervid species. Its taxonomic status remains unclear since the hypothesis of morphological polymorphism among males has been proposed. However, accurate taxonomy is fundamental in the identification and survey of potentially pathogenic species of parasites. The second internal transcribed spacer of rDNA (ITS-2) and the mitochondrial (mt) DNA-derived ND4 gene were used to study the polymorphism hypothesis for S. spiculoptera. ND4 evolves more quickly than ITS-2 and is considered to be more discriminant in the characterization of closely related species. DNA sequences of ITS-2 and ND4 were studied in 18 individual males of morphological type spiculoptera and in 3 of morphological type of mathevossiani from Red deer (Cervus elaphus), Roe deer (Capreolus capreolus) and Chamois (Rupicapra rupicapra). Intraindividual ITS-2 variations were detected within and between each morphotype of Spiculopteragia but these differences did not separate the two morphs mathevossiani and spiculoptera. Similarly, although ND4 showed a high level of nucleotide substitution, the morphotypes S. mathevossiani and S. spiculoptera were clustered together. Our genetic data support the dimorphic male hypothesis for the species S. spiculoptera.

ABOMASAL PARASITES IN WILD SYMPATRIC CERVIDS, RED DEER, CERVUS ELAPHUS AND FALLOW DEER, DAMA DAMA, FROM THREE LOCALITIES ACROSS CENTRAL AND WESTERN SPAIN: RELATIONSHIP TO HOST DENSITY AND PARK MANAGEMENT

A survey of abomasal parasites in cervids from Central Spain was conducted at 3 sites, Quintos de Mora (Toledo), Maluéñez de Arriba (Cáceres), and La Herguijuela (Cáceres). Commonly occurring helminths belonged to 3 polymorphic species of the Ostertagiinae: Spiculopteragia asymmetricalS. quadrispiculata, Ostertagia leptospicularis/O. kolchida, and O. drozdzi/O. ryjikovi. Trichostrongylus axei was found in very few cases. Ostertagia drozdzi/O. ryjikovi and the minor male morphotype, S. quadrispiculata, are reported for the first time in red deer from Spain. The 3 ostertagiine species are also reported for the first time in fallow deer from Spain. These 3 species of Ostertagiinae are primarily parasites of cervids, and nematode species characteristic of domestic ruminants were not present. Prevalence of infection by gastrointestinal parasites in cervids was high, ranging from 97.5 to 100%, across the 3 areas sampled. Mean intensity of infection and abundance showed a positive relationship to the population density of red deer. Helminth burdens were higher in fallow deer than in the sympatric red deer and may reflect the gregarious social structure and different foraging patterns of fallow deer.

A survey of the gastrointestinal nematodes of Spanish ibex (Capra pyrenaica) in a high mountain habitat

We analyzed the content of the abomasum (n = 79) and small intestine (n = 83) of Spanish ibex from Sierra Nevada Natural Park, southern Spain. Fifteen species of trichostrongylid nematodes were identified, 4 of which were found for the first time in this host, i.e., Nematodirus fillicollis, N. oiratianus, Ostertagia lyrata, and O. ostertagi. Teladorsagia circumcincta and Marshallagia marshalli were the most abundant abomasal species, whereas N. abnormalis, N. davtiani, and N. oiratianus were dominant in the small intestine. Counts of both abomasal and intestinal nematodes were generally low (year-round-median = 292 and 94 worms, respectively), and significantly lower numbers of M. marshalli, N. davtiani, and N. oiratianus were found in summer. No sex-related differences in helminth abundance were found, but young ibex harbored significantly more N. davtiani and N. oiratianus than adults. The presence of scabies was not related to increased nematode counts.

The population dynamics of Ostertagia gruehneri in reindeer: a model for the seasonal and intensity dependent variation in nematode fecundity

The gastrointestinal nematode Ostertagia gruehneri is a parasite of reindeer that can have a significant impact on host population dynamics. To gain a better understanding of the population dynamics of O. gruehneri, we parameterise a model for its fecundity that describes the observed seasonal and intensity dependent pattern of faecal egg counts well. The faecal egg count model is combined with a model for the seasonal faecal production rate of Svalbard reindeer to obtain quantitative estimates of the fecundity of O. gruehneri. The model is used to evaluate the relative contribution to pasture contamination of variation in the abundance of O. gruehneri and variation in reindeer densities. It is concluded that due to the intensity dependence in nematode fecundity, variation in reindeer population densities is likely to be the most important of these factors for pasture contamination.

Identical ITS-1 and ITS-2 sequences suggest Spiculopteragia asymmetrica and Spiculopteragia quadrispiculata (Nematoda: Trichostrongylidae) constitute morphologically distinct variants of a single species

Sequences of ITS-1 and ITS-2 rDNA for adult males of Spiculopteragia asymmetrica and Spiculopteragia quadrispiculata in red deer (Cervus elaphus) were determined. They were found to be identical, suggesting that S. asymmetrica and S. quadrispiculata represent a single species and do not refute the concept of dimorphic species in the Spiculopteragia.

DNA evidence that Marshallagia marshalli Ransom, 1907 and M. occidentalis Ransom, 1907 (Nematoda: Ostertagiinae) from Svalbard reindeer are conspecific

The gastro-intestinal parasitic nematodes of ruminants Marshallagia marshalli and M. occidentalis are morphs of a single species according to indirect evidence. In this study, their taxonomic status and molecular identification were assessed more directly in isolates from the abomasal nematode community of Svalbard reindeer using genetic data. DNA sequences of the first and second internal transcribed spacers of nuclear ribosomal RNA genes were obtained from individual nematodes by the polymerase chain reaction (PCR). Both taxa contained virtually identical sequences of each ITS and shared most of the polymorphisms detected. A PCR assay based on ITS-2 sequences previously developed to identify M. marshalli and Ostertagia gruehneri, the second common species in this community, gave identical results for M. marshalli and M. occidentalis. Genetic data thus confirmed that M. marshalli and M. occidentalis are conspecific.

Synlophe in Ostertagia cf. kasakhstanica (Nematoda: Ostertagiinae), the minor morphotype of O. bisonis from western North America

Ostertagia cf. kasakhstanica, the putative minor morphotype of the polymorphic ostertagiine O. bisonis, is reported in Bison bison from South Dakota. Descriptions of the synlophe and details of other diagnostic characters useful in identification and differentiation of this minor morphotype from other ostertagiines in wild and domestic ruminants from western North America are presented. Laterally, the cervical synlophe is consistent with Type Ib pattern among ostertagiines and is within the range of variation previously described for O. bisonis. Among recognized minor morphotypes of ostertagiines in wild and domestic ruminants from North America, O. kasakhstanica is distinct from O. kolchida, O. dikmansi, and O. arctica based on a tapering lateral synlophe. It is further distinguished from O. lyrata by the pattern of the cervical synlophe in the lateral field, structure of the genital cone and spicules, and dimensions of the esophageal valve. Although morphologically similar to T. davtiani/T. trifucata and T. boreoarcticus f. minor, it can be readily distinguished by the 2-1-2 bursal pattern, the structure of the spicules and genital cone, and the length of the esophageal valve. Ostertagia hisonis/O. cf. kasakhstanica circulates among pronghorn, mule deer, bison, and cattle in west-central North America.

Evolutionary relationships of trichostrongyloid nematodes (Strongylida) inferred from ribosomal DNA sequence data

The evolutionary relationships of 21 species of trichostrongyloid nematodes were determined by use of sequence data of the second internal transcribed spacer of the ribosomal DNA aligned according to secondary structure information. Irrespective of the method of analysis used, the topologies of the phylogenetic trees derived from the molecular data differed with respect to all four hypotheses proposed previously for the evolutionary relationships of the different subfamilies within the Trichostrongylidae based on morphological data. Thus, the molecular data set did not resolve the conflict between the four previous proposals for the subfamilial relationships. Nonetheless, all trees derived from the molecular data showed strong support for the exclusion of the genera Filarinema and Amidostomum from the clade containing the species within the family Trichostrongylidae. This represents a major difference from the most recent proposal of the systematics of the Trichostrongyloidea in which these two genera were included within the Trichostrongylidae. Therefore, the molecular data support an earlier systematic framework in which Filarinema and Amidostomum were considered to be sister groups of the Trichostrongyloidea.

DNA evidence that Ostertagia gruehneri and Ostertagia arctica (Nematoda: ostertagiinae) in reindeer from Norway and Svalbard are conspecific

DNA sequences of ITS-1 and ITS-2 of rDNA were determined for 16 individual adult males each of Ostertagia gruehneri and Ostertagia arctica from Svalbard reindeer (Rangifer tarandus platyrhynchus) and Eurasian tundra reindeer (R. t. tarandus). Each ITS was virtually identical in O. gruehneri and O. arctica and the three mixed bases detected were shared by both species. Our results strongly suggest that O. gruehneri and O. arctica are dimorphic males of the same species.

Parasites, biodiversity, and population dynamics in an ecosystem in the high arctic

The abomasa of 163 Svalbard reindeers (Rangifer tarandus platyrhynchus) from Nordenskiöld Land, Spitsbergen (78 degrees N, 15 degrees E) were examined for adult and juvenile nematodes. Spitsbergen has midnight sun from late April to late August, arctic night from late October to mid-February, permafrost, and snow cover from October to June. Plant growth is restricted to 6-8 weeks, usually starting mid-June. In the reindeer calves, which are born in June prevalence and intensity of infection increased over the winter. All young (1 year) and adult (older than 1 year) reindeers were infected. Variations in worm burden, fraction of adult nematodes, male to female ratio in the nematodes, number of adult nematodes, number of juvenile nematodes, and distribution of juvenile nematodes on length groups were analysed for relationships with sex and age of host, and time of the year. The material was further analysed for relationships between the reindeer's content of stored fat and worm burden and its elements. It is concluded that transmission of nematodes to the reindeer continues over the winter and that arrested larval development has not been strongly selected for in this High Arctic locality. Infection continued to increase in adult males but not in adult females with age. This is explained as a balance between gain and loss of worms in the females connected to levelling off of food intake at end of somatic growth. In adult male reindeers there was a negative trend between stored fat and infection at all seasons. In reproducing females there were significant negative relationships in winter-spring, while in yeld females no significant relationship was found. The nematodes belonged to the following taxa: Ostertagia gruehneri m. gruehneri, O. gruehneri m. arcticus, Marshallagia marshalli m. marshalli, M. marshalli. m. occidentalis, Teladorsagia circumcincta m. circumcincta, T. circumcincta. m. trifurcata, and T. circumcincta. m. davtiani. There appears not to be any specially adapted species among the helminth parasites of reindeer (Rangifer tarandus) and muskoxen (Ovibos moschatus) in the High Arctic. In the Low Arctic Uminmakstrongylus pallikuukensis of muskoxen may be an example of such adaptation.