Ashworthius sidemi Schulz, 1933 and Haemonchus contortus (Rudolphi, 1803) in cervids in France: integrative approach for species identification

Molecular uncovering of important helminth species in wild ruminants in the Czech Republic

Monitoring gastrointestinal helminth infections in wild ruminants poses significant challenges for managing wildlife health, particularly regarding invasive species. Traditional coprological methods are often limited by their labor-intensive nature and potential for erroneous identification due to morphological similarities among parasite species. This study employed advanced molecular techniques to assess the prevalence and distribution of several helminth taxa, including the invasive nematode Ashworthius sidemi and the trematode Fascioloides magna, in wild ruminant populations in the Czech Republic (CR). A comprehensive and extensive survey on parasite occurrence, unique in its nationwide scope, was conducted on 983 fecal samples collected from red deer (Cervus elaphus), roe deer (Capreolus capreolus), fallow deer (Dama dama), and mouflon (Ovis musimon) across various regions of the CR. The samples were analyzed using multiplex real-time PCR assays specifically designed to detect the DNA of six helminth representatives: the nematodes A. sidemi and Haemonchus spp., as well as the trematodes F. magna, Dicrocoelium dendriticum, Fasciola hepatica, and Calicophoron daubneyi (and representatives of the family Paramphistomidae, respectively). These assays targeted regions of ribosomal DNA (rDNA) and were designed to exhibit high sensitivity and specificity, enabling accurate detection of helminth parasites directly in fecal samples. The molecular assays revealed that invasive nematode A. sidemi was the most prevalent helminth species, detected in 15.8% of all samples (155/983), with the highest infection rate observed in red deer at 30.7% (124/404). Haemonchus spp. were also frequently detected, identified in 14.9% of samples (146/983), particularly in roe deer, with a prevalence of 23.2% (86/371). Spatial analysis of these nematodes across various regions of the CR revealed the extensive distribution of both A. sidemi and Haemonchus spp. in nearly all regions. In contrast, trematode infections were less common, with F. magna and D. dendriticum each found in only 1.5% of samples (15/983). Members of the family Paramphistomidae were detected in 0.2% of the samples (2/983) and were confirmed through sequencing as C. daubneyi. The geographical distribution patterns identified in this study indicate potential hotspots for specific helminth species. These findings are critical for planning health management and conservation strategies to mitigate the impacts of helminth infections, especially in areas affected by invasive species.

First molecular identification of Haemonchus contortus (Nematoda: Trichostrongylidae), a blood-sucking gastric nematode of artiodactyles, in the ground beetle Carabus granulatus (Coleoptera: Carabidae)

Among gastrointestinal nematodes, Haemonchus contortus (Rudolphi) Cobb (order Strongylidae; family Trichostrongylidae) is one of pathogenic and economic importance in domestic and wild ruminants, including the European bison, Bison bonasus Linnaeus (order Cetartiodactyla; family Bovidae); a species on the International Union for Conservation of Nature's Red List of Threatened Species. Carabus granulatus Linnaeus (order Coleoptera; family Carabidae) is one of the most prevalent species of ground beetle, inhabiting a wide range of terrestrial ecosystems in Poland. Twenty-six ground beetles of this species inhabiting the Białowieża Primeval Forest in eastern Poland were screened for the presence of DNA of pathogenic gastrointestinal nematodes of ruminants. Extracted DNA was sequenced and compared to reference sequences. In six insects, the presence of H. contortus DNA was detected. The obtained nucleotide sequences were homologous to each other and to the majority of the published DNA sequences of H. contortus isolates. The sequences were also identical to a sequence of H. contortus isolated from European bison in Poland. The study provides the first molecular evidence of the presence of H. contortus DNA in C. granulatus. The finding suggests that ground beetles may play a role in the transmission dynamics of this parasite.

A molecular assessment of Ostertagia leptospicularis and Spiculopteragia asymmetrica among wild fallow deer in Northern Ireland and implications for false detection of livestock-associated species

BACKGROUND

Wild deer populations utilizing livestock grazing areas risk cross-species transmission of gastrointestinal nematode parasites (GINs), including GINs with anthelmintic resistance (AR) traits. Wild deer have been shown to carry problematic GIN species such as Haemonchus contortus and Trichostrongylus species in the UK, but the presence of livestock GINs in Northern Ireland deer populations is unknown. Also, is it not known whether AR traits exist among GINs of deer such as Ostertagia leptospicularis and Spiculopteragia asymmetrica in pastureland where anthelmintics are heavily used.

METHODS

Adult-stage GIN samples were retrieved from Northern Irish wild fallow deer abomasa. Individual specimens were subject to a species-specific PCR analysis for common sheep and cattle GIN species with ITS-2 sequence analysis to validate species identities. In addition, the beta-tubulin gene was subject to sequencing to identify benzimidazole (BZ) resistance markers.

RESULTS

ITS-2 sequencing revealed O. leptospicularis and S. asymmetrica, but species-specific PCR yielded false-positive hits for H. contortus, Teladorsagia circimcincta, Trichostrongylus axei, T. colubriformis, T. vitrinus and Ostertagia ostertagi. For beta-tubulin, O. leptospicularis and S. asymmetrica yielded species-specific sequences at the E198 codon, but no resistance markers were identified in either species at positions 167, 198 or 200 of the coding region.

DISCUSSION

From this report, no GIN species of significance in livestock were identified among Northern Ireland fallow deer. However, false-positive PCR hits for sheep and cattle-associated GINs is concerning as the presence of deer species in livestock areas could impact both deer and livestock diagnostics and lead to overestimation of both GIN burden in deer and the role as of deer as drivers of these pathogens. ITS-2 sequences from both O. leptospicularis and S. asymmetrica show minor sequence variations to geographically distinct isolates. AR has been noted among GINs of deer but molecular analyses are lacking for GINs of wildlife. In producing the first beta-tubulin sequences for both O. leptospicularis and S. asymmetrica, we report no BZ resistance in this cohort.

CONCLUSIONS

This work contributes to genetic resources for wildlife species and considers the implications of such species when performing livestock GIN diagnostics.

Parasitic strongyle nemabiome communities in wild ruminants in Sweden

Background

Wildlife hosts may serve as reservoirs for strongyles, which can be transmitted to domestic livestock. Therefore, studies evaluating nemabiome compositions in wildlife ruminants are of great use in assessing the possibility of transmission of important nematode pathogens to domestic sheep in Sweden.

Methods

First, fecal samples were collected from roe deer (n = 125), fallow deer (n = 106), red deer (n = 18) and mouflon (n = 13) in south central Sweden during the hunting season in 2019. Second, after fecal examination samples were cultured and the larvae were harvested, followed by DNA extractions. Third, all samples were barcoded and processed for sequence analysis on the PacBio platform. Finally, bioinformatic sequence analysis was conducted with DADA2, while species diversity and richness, as well as interactions between the different hosts, were calculated and analyzed in R.

Results

Nematode ITS2 sequences were found in 225 of 262 (86%) samples. In total, 31 taxa were identified, among which 26 (86%) to the species level. These were found in different combinations, among which 24 (77%) occurred in roe deer, 19 (61%) in fallow deer, 20 (65%) in red deer and 10 (32%) in mouflon. Five of the species found are known to be associated with livestock (Chabertia ovina, Haemonchus contortus, Oesophagostomum venulosum, Teladorsagia circumcincta and Trichostrongylus axei). However, in the present study the relative abundance and prevalence of most of these species were low. The most striking exception was T. axei, which was relatively abundant in all wildlife hosts. Mostly a wide range of wildlife specific nematodes such as Ostertagia leptospicularis and Spiculopteragia spp. were identified including the invasive nematode Spiculopteragia houdemeri, which was found for the first time in red deer, fallow deer, and mouflon in Sweden. The difference in the number of shared species between mouflon and all cervids (n = 6) was less than among all three cervids (n = 8).

Conclusion

In this study, we investigated the community structure of parasitic intestinal nematodes in four wildlife hosts, and we found that the majority of the parasite species identified were wildlife specific. We also found a new, potentially invasive species not reported before. After comparing the nemabiome of the wildlife hosts in this study with a previous study in sheep from the same geographical region, we conclude that the horizontal transmission potential appears to be relatively low. Still, cross-infections of nematodes between game and sheep cannot be completely ignored.

Graphical Abstract

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.

The First Detection of Abomasal Nematode Ashworthius sidemi in Fallow Deer (Dama dama) in Russia

PURPOSE

The aim of the study was to supplement the data concerning the spreading of nematode Ashworthius sidemi among wild ruminants in Russia.

METHODS

The samples of A. sidemi were collected from two fallow deer, which were born and raised in the game farm in Smolensk region (55° 16' N-34° 29' E). The affiliation of the detected nematodes as A. sidemi was made using morphological features (shape of the spicules and the dorsal ray of bursa for males, as well as the presence and shape of the neodont in the buccal cavity for males and females).

RESULTS

The intensity of infection in 2 studied fallow deer was 7 and 19 individuals of A. sidemi. All of the specimens of A. sidemi had the features of juvenile forms. The registration of fallow deer as another one host of A. sidemi in Russia indicates a further spreading of this nematode and confirms the necessity of strengthening the control of this parasite.

CONCLUSION

The finding of this nematode in non-native captive animals shows the imperfection of control in this sphere. A. sidemi could have been introduced to the game farm both with imported or with native animals due to insufficient quarantine and isolation. More wide further research would be useful in the light of control this potentially dangerous parasite.

Metabarcoding in two isolated populations of wild roe deer (Capreolus capreolus) reveals variation in gastrointestinal nematode community composition between regions and among age classes

Background

Gastrointestinal nematodes are ubiquitous for both domestic and wild ungulates and have varying consequences for health and fitness. They exist as complex communities of multiple co-infecting species, and we have a limited understanding of how these communities vary in different hosts, regions and circumstances or of how this affects their impacts.

Methods

We have undertaken ITS2 rDNA nemabiome metabarcoding with next-generation sequencing on populations of nematode larvae isolated from 149 fecal samples of roe deer of different sex and age classes in the two isolated populations of Chizé and Trois Fontaines in France not co-grazing with any domestic ungulate species.

Results

We identified 100 amplified sequence variants (ASVs) that were assigned to 14 gastrointestinal nematode taxa overall at either genus (29%) or species (71%) level. These taxa were dominated by parasites classically found in cervids—e.g. Ostertagia leptospicularis, Spiculopteragia spp. Higher parasite species diversity was present in the Trois Fontaines population than in the Chizé population including the presence of species more typically seen in domestic livestock (Haemonchus contortus, Bunostomum sp., Cooperia punctata, Teladorsagia circumcincta). No differences in parasite species diversity or community composition were seen in the samples collected from three zones of differing habitat quality within the Chizé study area. Young roe deer hosted the highest diversity of gastrointestinal nematodes, with more pronounced effects of age apparent in Trois Fontaines. The effect of host age differed between gastrointestinal nematode species, e.g. there was little effect on O. leptospicularis but a large effect on Trichostrongylus spp. No effect of host sex was detected in either site.

Conclusions

The presence of some livestock parasite species in the Trois Fontaines roe deer population was unexpected given the isolation of this population away from grazing domestic livestock since decades. Overall, our results illustrate the influence of host traits and the local environment on roe deer nemabiome and demonstrate the power of the nemabiome metabarcoding approach to elucidate the composition of gastrointestinal nematode communities in wildlife.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05087-5.

Nematicidal Effect of Shiitake (Lentinula edodes) Extracts Against Haemonchus contortus

During the previous decades, the indiscriminate use of anthelmintics for the control of gastrointestinal nematodes has generated anthelmintic resistance in different parts of the world. It is necessary to search for new sustainable control alternatives, such as the use of extracts from plants and edible mushrooms. Therefore, the aim of the present study was to evaluate the nematicidal activity of extracts and fractions of the edible mushroom Lentinula edodes against Haemonchus contortus eggs and infective larvae. The basidiomata of L. edodes ECS-401 were provided by the Tropical Fungi Laboratory of El Colegio de la Frontera Sur and were extracted with ethyl acetate, methanol, and water. Fractionation of the most active extract was carried out by open column chromatography. The bioassays were performed in 96-well microtiter plates using 100 eggs/larvae, a final volume of 100 μL, and different concentrations of extracts/fractions (n = 4). Bioassay readings were taken at 48 h for egg hatching inhibition (EHI) and at 24, 48 and 72 h for larval mortality (LM). The ethyl acetate extract exhibited the highest percentage of EHI (100%). For the LM bioassay, the aqueous extract was the most active (69%), but its fractions did not show larvicidal activity. The chemical profile of the aqueous extract was analyzed by high-performance liquid chromatography, which showed the presence of phenols, flavonoids, and terpenes. L. edodes extracts showed ovicidal and/or larvicidal activity.

Ashworthius sidemi Schulz, 1933 (Trichostrongylidae: Haemonchinae) in mountain ecosystems - a potential risk for the Tatra chamois Rupicapra rupicapra tatrica (Blahout, 1971/1972)

The Asian native Ashworthius sidemi is now in Europe, and several dozen years after its introduction, it is a widespread parasite of all wild cervids. For bovids, the nematode is a significant threat to the European bison (Bison bonasus) population and has also been found in mouflon (Ovis ariesmusimon). Our study aimed to assess the risk of infection for the endemic subspecies of northern (Alpine) chamois (Rupicapra rupicapra) – the Tatra chamois (R. r. tatrica), which has a critically endangered status. We conducted the investigation in the mountainous areas of Slovakia and Poland occupied by Tatra chamois (R. r. tatrica), Alpine chamois (R. r. rupicapra), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Animals (n = 93) shot during licensed hunting and killed in road accidents (roe deer, red deer), or which had died of natural causes (chamois) were post-mortem examined for the presence of Haemonchinae. The investigation confirmed the expansion of Ashworthius sidemi to high mountain regions via Cervidae. A. sidemi affected all of the examined roe deer and 90.0% of the red deer. As for the chamois, A. sidemi was found in one R. rupicapra originating from the Low Tatras, but not in any pure R. r. tatrica individuals living in the High and Western Tatras. Our work is the first confirmation of northern chamois infection with this alien and highly pathogenic blood-sucking nematode. Due to the important health hazard of A. sidemi infection for the Tatra chamois (R. r. tatrica), appropriate measures should be taken to reduce the possibility of parasite transmission between various cervid species living in the Tatra region, as well as the affected population of chamois and the pure Tatra chamois population inhabiting the higher parts of the mountains, constituting their natural habitat.

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A. sidemi distribution extends with cervid hosts into the high mountains.

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A. sidemi infection in northern chamois is confirmed for the first time.

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Critically endangered Tatra chamois becomes substantially exposed to A. sidemi.

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.

The use of high resolution melting analysis of ITS-1 for rapid differentiation of parasitic nematodes Haemonchus contortus and Ashworthius sidemi

Among gastrointestinal nematodes, haematophagous strongylids Haemonchus contortus and Ashworthius sidemi belong to the most pathogenic parasites of both domestic and wild ruminants. Correct identification of parasitic taxa is of crucial importance in many areas of parasite research, including monitoring of occurrence, epidemiological studies, or testing of effectiveness of therapy. In this study, we identified H. contortus and A. sidemi in a broad range of ruminant hosts that occur in the Czech Republic using morphological/morphometric and molecular approaches. As an advanced molecular method, we employed qPCR followed by High Resolution Melting analysis, specifically targeting the internal transcribed spacer 1 (ITS-1) sequence to distinguish the two nematode species. We demonstrate that High Resolution Melting curves allow for taxonomic affiliation, making it a convenient, rapid, and reliable identification tool.

The first detection of Ashworthius sidemi (Nematoda, Trichostrongylidae) in roe deer (Capreolus capreolus) in Russia

Ashworthius sidemi is a blood-sucking nematode, which has spread out among wild ruminants in several European countries during last decades. The nematode has recently been detected in cattle as well. The distribution of A. sidemi in Russia has not been sufficiently clarified yet. In European part of Russia A. sidemi was formerly registered in sika deer (Cervus nippon) and maral (Cervus elaphus sibiricus) introduced from Asia, and also in aboriginal elks (Alces alces). Taking into consideration the presence of other species of ruminants susceptible to A. sidemi in European Russia, it is necessary to control the spread of this parasite. The specimens of males and females of A. sidemi were found during the autopsies of three naturally infected roe deer (Capreolus capreolus) from Voronezh and Tver regions (European Russia). The species affiliation of the discovered nematodes was determined according to morphological features and confirmed using molecular techniques. The intensity of infection with A. sidemi in two roe deer from Voronezh was 11 and 63 nematodes, and it was 17 nematodes in roe deer from Tver. All of the discovered specimens of A. sidemi were referred to juvenile forms based on features of male bursa morphology and weak development of female reproductive system. In Russia, A. sidemi has not previously been detected in C. capreolus and the present report constitutes the first record of the parasite occurrence in this species of ruminant.