Dictyocaulus Species Research Articles

The first finding of Dictyocaulus cervi and Dictyocaulus skrjabini (Nematoda) in feral fallow deer (Dama dama) in Australia

Feral deer are widespread throughout Australia with the capacity to impact livestock production via transmission of parasites. Samples of Dama dama (fallow deer), Rusa unicolor (sambar deer), Cervus elaphus (red deer) and an unidentified deer were sourced from various locations in south-eastern Australia for examination for parasites. Adult nematodes were collected from the lungs of all deer species across four separate geographical locations. The nematodes were identified as species of Dictyocaulus through both morphological and molecular means. Species identification based on morphological features was difficult, with many measurements from described species overlapping. Molecular analyses targeting three markers, namely 18S rRNA, ITS2, and cox1 revealed the presence of two distinct species: Dictyocaulus cervi and Dictyocaulus skrjabini. These are the first genetically confirmed reports of species of Dictyocaulus in feral deer in Australia, and although cross-transmission of species of Dictyocaulus with livestock has not yet been reported, it cannot be completely discounted without further research.

Morphological and molecular description of Dictyocaulus xanthopygus sp. nov. (Nematoda: Trichostrongyloidea) from the Manchurian wapiti Cervus elaphus xanthopygus.

Dictyocaulus xanthopygus sp. nov. (Nematoda: Trichostrongyloidea) was isolated from the lungs of the Manchurian wapiti in Primorsky kray, Russia. The newly described species exhibits morphological characteristics of Dictyocaulus but is distinct from congeneric species based on morphological (lengths of body and esophagus, distances from the anterior end to nerve ring and to excretory pore, the thickness of the buccal capsule, etc.) and molecular features. High levels of genetic divergence as well as Bayesian phylogenetic analyses based on 18S rRNA nuclear and cox1 mitochondrial genes supported the independence of Dictyocaulus xanthopygus sp. nov. Secondary structures of helix 39 of 18S rRNA were identical, while ES9 adjacent to the helix has a unique conformation for newly described worms. Energy-efficient conformational rearrangements of rRNA secondary structures can be applicable in studies on the pathogenesis, epidemiology, taxonomy and evolutionary biology of parasites. Additionally, bracketed dichotomous keys to six valid species of Dictyocaulus were prepared.

Opening a can of lungworms: Molecular characterization of Dictyocaulus (Nematoda: Dictyocaulidae) infecting North American bison (Bison bison).

Dictyocaulus is a globally distributed genus of lungworms of domestic and wild ungulates. Dictyocaulus adults inhabit the bronchi, frequently causing subclinical and clinical disease, and that impacts animal health and production. North American bison (Bison bison) and cattle (Bos taurus) share various parasitic nematode species, particularly in areas where co-grazing occurs. The current assumption is that North American bison share the lungworm D. viviparus with cattle, but this has not been confirmed on a molecular basis. The aim of this study was to molecularly characterize Dictyocaulus lungworm isolates from North American plains bison (Bison bison bison). Fecal samples were collected from 5 wild conservation bison herds located in Iowa, North Dakota, Oklahoma, Colorado, and Montana in 2019 and 2020, and from ranched and feedlot bison from 2 herds in Oklahoma and Texas. First-stage lungworm larvae (L1) were isolated via Baermann technique. Genomic DNA was extracted from L1s of up to 3 samples per herd and followed by PCR and sequencing targeting the internal transcribed spacer 2 (ITS2) region of the nuclear ribosomal DNA and the partial cytochrome oxidase c subunit 1 (cox1) of mitochondrial DNA. Phylogenetic analyses were performed in MEGA X 10.1. Sequences of North American plains bison Dictyocaulus belong to a single, uncharacterized species, clustering in well-supported clades (100% and 100% bootstrap support for ITS2 and cox1, respectively), differing from D. viviparus of cattle in North America and Europe, and European bison (Bison bonasus). Our results contradict previous assumptions regarding parasite identity, highlighting the need for characterization of this species through morphological and molecular methods, elucidating its biology and host range, and potential impact on host health. Further investigation into the biodiversity of Dictyocaulus species infecting bovids and cervids in North America is warranted.

Tick infestations and gastrointestinal helminthosis among goats and cattle at abattoirs in Abakaliki Metropolis, Ebonyi State, Nigeria

Parasitism and parasitosis constitute serious animal health problems that predispose them to other more serious health conditions. Such conditions can reduce their productivity and marketability, thereby reducing their economic values. A total of 126 livestock comprising 63 goats and 63 cattle from abattoirs in Abakaliki Metropolis were subjected to ectoparasitic and gastrointestinal parasitic examinations, using approved standard diagnostic parasitological techniques. The recovered parasites were identified with standard identification guides. Rhipicephalus sanguineus and R. microplus were the two recovered ectoparasites from both groups of animal. There was no significant difference (p = 0.0859) in the prevalence of the tick species between the animals. Dictyocaulus species was the most abundant gastrointestinal helminth infecting both goats and cattle. There was no complete dominance of parasite species infecting the two groups of animal but the Shannon-Weiner diversity index indicated high parasite diversity for both goats and cattle. Periodic application of efficacious acaricides mixed (sequential) grazing and regular deworming with the use of strategic broad spectrum chemotherapeutic anthelmintics are strongly recommended. Keywords : Cattle; goats; helminthes; infestations; tick.

Southern pudu (Pudu puda) (Artiodactyla: Cervidae) as an additional host for Dictyocaulus eckerti (Strongylida: Dictyocaulidae)

Southern pudu ( Pudu puda Molina, 1782) is the most austral native deer in South America, being distributed in Chile and Argentina, countries where it has conservation issues. Seven lungworms were isolated from the bronchi of one southern pudu from Los Rios region. Such helminths were identified as adult females and males of Dictyocaulus eckerti Skrjabin, 1931, a lungworm isolated in wild and domestic deers from Europe, New Zealand and North America. There are previous reports of unidentified species of Dictyocaulus in P. puda from Southern Chile. However, this is the first record of P. puda acting as a natural host of D. eckerti . Due to the establishment of wild populations of European deers in Southern Chile, sharing grazing places between native and exotic deers could allow for the transmission of such parasites. Thus, the present report highlights the potential additional impact of exotic mammals over this threatened deer.

Analysis of the transcriptome of adult Dictyocaulus filaria and comparison with Dictyocaulus viviparus, with a focus on molecules involved in host–parasite interactions

Parasitic nematodes cause diseases of major economic importance in animals. Key representatives are species of Dictyocaulus (=lungworms), which cause bronchitis (=dictyocaulosis, commonly known as “husk”) and have a major adverse impact on the health of livestock. In spite of their economic importance, very little is known about the immunomolecular biology of these parasites. Here, we conducted a comprehensive investigation of the adult transcriptome of Dictyocaulus filaria of small ruminants and compared it with that of Dictyocaulus viviparus of bovids. We then identified a subset of highly transcribed molecules inferred to be linked to host–parasite interactions, including cathepsin B peptidases, fatty-acid and/or retinol-binding proteins, β-galactoside-binding galectins, secreted protein 6 precursors, macrophage migration inhibitory factors, glutathione peroxidases, a transthyretin-like protein and a type 2-like cystatin. We then studied homologues of D. filaria type 2-like cystatin encoded in D. viviparus and 24 other nematodes representing seven distinct taxonomic orders, with a particular focus on their proposed role in immunomodulation and/or metabolism. Taken together, the present study provides new insights into nematode–host interactions. The findings lay the foundation for future experimental studies and could have implications for designing new interventions against lungworms and other parasitic nematodes. The future characterisation of the genomes of Dictyocaulus spp. should underpin these endeavours.

Assessment of the genetic relationship between Dictyocaulus species from Bos taurus and Cervus elaphus using complete mitochondrial genomic datasets

BackgroundDictyocaulus species are strongylid nematodes of major veterinary significance in ruminants, such as cattle and cervids, and cause serious bronchitis or pneumonia (dictyocaulosis or “husk”). There has been ongoing controversy surrounding the validity of some Dictyocaulus species and their host specificity. Here, we sequenced and characterized the mitochondrial (mt) genomes of Dictyocaulus viviparus (from Bos taurus) with Dictyocaulus sp. cf. eckerti from red deer (Cervus elaphus), used mt datasets to assess the genetic relationship between these and related parasites, and predicted markers for future population genetic or molecular epidemiological studies.MethodsThe mt genomes were amplified from single adult males of D. viviparus and Dictyocaulus sp. cf. eckerti (from red deer) by long-PCR, sequenced using 454-technology and annotated using bioinformatic tools. Amino acid sequences inferred from individual genes of each of the two mt genomes were compared, concatenated and subjected to phylogenetic analysis using Bayesian inference (BI), also employing data for other strongylids for comparative purposes.ResultsThe circular mt genomes were 13,310 bp (D. viviparus) and 13,296 bp (Dictyocaulus sp. cf. eckerti) in size, and each contained 12 protein-encoding, 22 transfer RNA and 2 ribosomal RNA genes, consistent with other strongylid nematodes sequenced to date. Sliding window analysis identified genes with high or low levels of nucleotide diversity between the mt genomes. At the predicted mt proteomic level, there was an overall sequence difference of 34.5% between D. viviparus and Dictyocaulus sp. cf. eckerti, and amino acid sequence variation within each species was usually much lower than differences between species. Phylogenetic analysis of the concatenated amino acid sequence data for all 12 mt proteins showed that both D. viviparus and Dictyocaulus sp. cf. eckerti were closely related, and grouped to the exclusion of selected members of the superfamilies Metastrongyloidea, Trichostrongyloidea, Ancylostomatoidea and Strongyloidea.ConclusionsConsistent with previous findings for nuclear ribosomal DNA sequence data, the present analyses indicate that Dictyocaulus sp. cf. eckerti (red deer) and D. viviparus are separate species. Barcodes in the two mt genomes and proteomes should serve as markers for future studies of the population genetics and/or epidemiology of these and related species of Dictyocaulus.

Effect of altitude and animal age on the prevalence of dictyocaulosis in cattle in the Northern Province of Rwanda

This research was done in the North-western region of Rwanda and the aim of the study was to determine the prevalence of bovine dictyocaulosis and influences of altitude and age on infestation in the region. Dictyocaulosis is a parasitic disease caused by the presence and the development of parasite Dictyocaulus species in the lung. On a random sample of 1470 slaughtered animals, the study revealed 68 cases of dictyocaulosis, which represents 4.6% of the total of the slaughtered animals, with variations of between 1.3 and 7.5% in different sites. The study showed a variation of the prevalence, which is related to altitude (from 1470 to 3000 m) and age (p < 0.05). There is need to craft specific measures against dictyocaulosis in the areas of high altitude of Rwanda. Key words: Altitude, bovine, dictyocaulosis, lung, prevalence, Rwanda.

Characterization of Dictyocaulus Species (Nematoda: Trichostrongyloidea) from Three Species of Wild Ruminants in Northwestern Spain

Specimens of Dictyocaulus spp. were extracted from the respiratory tracts of 3 ruminant hosts including roe deer (Capreolus capreolus), red deer (Cervus elaphus), and chamois (Rupicapra rupicapra) from wild populations in the province of Le6n, northwestern Spain. The near-complete nuclear small-subunit ribosomal RNA gene, and 2 regions of the large-subunit ribosomal RNA gene, were amplified by PCR and sequenced. The SSU rDNA gene sequences indicated a high level of similarity between the isolate from C elaphus and the published sequences for Dictyocaulus eckerti. SSU rDNA gene sequences were identical in the isolates from C. capreolus and R. rupicapra, and both corresponded to published sequences for D. capreolus. The LSU rDNA gene sequences differed in isolates from the latter 2 hosts, indicating the possible presence of an undescribed Dictyocaulus sp. in R. rupicapra. These results showed that the LSU rDNA gene sequences are useful indicators of genetic and species diversity in species of Dictyocaulus.

Limited sequence variation in the major sperm protein 1 (MSP) gene within populations and species of the genus Dictyocaulus (Nematoda)

Populations of the bovine lungworm, Dictyocaulus viviparus, are genetically structured based on variation in mtDNA and AFLP data. Our aim was to investigate if this genetic variability also is reflected in a protein recognized by the host immune system. We focused on the major sperm protein (MSP), a small and abundant protein used in diagnostic immunoassays, which has been shown to be variable in some nematodes but not others. MSP was sequenced using worm DNA from eight adult worms from each of nine populations whose genetic structure previously had been quantified. For comparison, we also analyzed MSP sequences of the closely related Dictyocaulus eckerti and Dictyocaulus capreolus and from nematodes with sequences deposited in GenBank. In contrast to previous results, this study shows that the MSP ofD. viviparus is similar to that of other nematodes. Almost no sequence variation, and thus no antigenic diversity, was detected in MSP between worms from different sub-populations or in the other Dictyocaulus species investigated. A functional test of a recombinant variant of the MSP showed that the expressed protein was recognized by antibodies in sera from infected cattle. This has practical implications for the development of species-specific markers, recombinant vaccines, and immunodiagnostics.

An electrophoretic tool for the genetic characterisation and delineation of lungworms

In the present study, PCR-based single-strand conformation polymorphism (SSCP) analysis of the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) was applied to the genetic characterisation of Dictyocaulus from red deer from New Zealand and to its differentiation from species of lungworm from cattle and other hosts. Based on SSCP profiles, Dictyocaulus individuals from red deer from different geographical localities in New Zealand could be readily distinguished from those representing other lungworms examined, irrespective of low-level sequence variability in the ITS-2 (0.4–2.6%) detectable among individuals. The ITS-2 of Dictyocaulus from red deer differed in sequence by ∼7–35% from congeners from other cervid hosts, demonstrating that this parasite is genetically distinct from other species of Dictyocaulus for which ITS-2 sequence data are presently available. The results emphasize the need for a large-scale molecular systematic study of Dictyocaulus specimens from various species of cervid and other ruminant hosts and the usefulness of mutation scanning for taxonomic, epidemiological and population genetic investigations.

Phylogeny of Dictyocaulus (lungworms) from eight species of ruminants based on analyses of ribosomal RNA data.

In this study, we conducted phylogenetic analyses of nematode parasites within the genus Dictyocaulus (superfamily Trichostrongyloidea). Lungworms from cattle (Bos taurus), domestic sheep (Ovis aries), European fallow deer (Dama dama), moose (Alces alces), musk ox (Ovibos moschatus), red deer (Cervus elaphus), reindeer (Rangifer tarandus) and roe deer (Capreolus capreolus) were obtained and their small subunit ribosomal RNA (SSU) and internal transcribed spacer 2 (ITS2) sequences analysed. In the hosts examined we identified D. capreolus, D. eckerti, D. filaria and D. viviparus. However, in fallow deer we detected a taxon with unique SSU and ITS2 sequences. The phylogenetic position of this taxon based on the SSU sequences shows that it is a separate evolutionary lineage from the other recognized species of Dictyocaulus. Furthermore, the analysis of the ITS2 sequence data indicates that it is as genetically distinct as are the named species of Dictyocaulus. Therefore, either this taxon needs to be recognized as a new species, or D. capreolus, D. eckerti and D. viviparus need to be combined into a single species. Traditionally, the genus Dictyocaulus has been placed as a separate family within the superfamily Trichostrongyloidea. The present molecular phylogenetic analyses support the placement as a separate family, but the current data do not support the placement of the Dictyocaulidae within the Trichostrongyloidea without a reassessment of the placement of the superfamily Strongyloidea. While D. eckerti has been regarded as the one and only lungworm species of cervids, this study showed that 4 host species including 3 members of Cervidae (moose, reindeer, red deer) and 1 Bovidae (musk ox) were infected with this parasite. Host ranges of D. viviparus (cattle), D. filaria (sheep) and D. capreolus (moose and roe deer) were more restricted. No clear pattern of co-evolution between the dictyocaulid taxa and their bovid and cervid hosts could be determined.

Dictyocaulus species: cross infection between cattle and red deer

AIM: To discover whether cross infection between red deer (Cervus elaphus) and cattle is possible with either a bovine isolate of the cattle lungworm, Dictyocaulus viviparus, or with a cervine isolate of the lungworm, Dictyocaulus eckerti. METHOD: Twelve cattle and 12 red deer were reared parasitefree from birth. At 3–4 months of age, half of each group (n=6) were experimentally infected with D. viviparus and the other half with D. eckerti. The course of infection was monitored for 34 days, after which the animals were slaughtered and the lungs removed to assess levels of infection. RESULTS: Faecal larval counts demonstrated that patent Dictyocaulus infections occurred in all groups. At necropsy, adult worms were found in the lungs in all groups except the cattle that were infected with D. eckerti. The largest numbers of adult worms were found in the lungs of the red deer infected with D. eckerti. CONCLUSION: It was demonstrated that both cattle and red deer could be infected with either D. viviparus or D. eckerti. However, D. eckerti larvae that originated from deer established more successfully in deer and D. viviparus larvae that originated from cattle established more successfully in cattle.

Dictyocaulus capreolus n. sp. (Nematoda: Trichostrongyloidea) from roe deer, Capreolus capreolus and moose, Alces alces in Sweden.

Dictyocaulus capreolus n. sp. recovered from roe deer, Capreolus capreolus and moose, Alces alces in Sweden is described and figured. Morphological studies revealed the new species to be closest to D. eckerti and D. africanus on the basis of mouth shape, all three species having an elongate mouth opening. The other species of the genus, including D. viviparus, all have a circular to oval mouth opening. Dictyocaulus capreolus n. sp. can be distinguished from D. eckerti and D. africanus on the basis of the morphology of the buccal capsule and the bursa. These morphological studies support earlier evidence of the presence of a new species of Dictyocaulus in roe deer and moose that could be distinguished from D. eckerti and D. viviparus using either a PCR-linked hybridization assay or image analysis software to study the dimensions of the buccal capsule.

Identification of Dictyocaulus spp. in ruminants by morphological and molecular analyses

Lungworms of the genus Dictyocaulus from cattle, roe deer, and moose in Sweden were subjected to morphological and molecular analyses. The objectives of the study were to investigate whether mixed or monospecific Dictyocaulus infections occur in Swedish cattle and whether wild cervids may act as reservoirs. The morphological characters examined were thickness and shape of the buccal capsule wall (BCW) and total spicular length (TSL). Morphometry was also done on the total body length, and BCW thickness and length. In the molecular identification, we used a PCR-linked hybridization assay to probe worm DNA with species-specific oligonucleotide probes to the second internal transcribed spacer (1TS2). The results showed that the BCW shape was the most reliable morphological character for identification. Significant differences were observed in this character, but an overlap occurred between lungworms from each of the host species. With the hybridization assay, all lungworms from cattle were identified as D. viviparus, whereas those from roe deer represented a novel Dictyocaulus species demonstrating that each host had a monospecific lungworm infection. In moose, 61 (78.2%) worms belonged to the new species and 17 (21.8%) were D. eckerti. This study shows the usefulness of hybridization assay as an epidemiological tool for the specific identification of lungworms of cattle and wild cervids.

ITS2 sequences of Dictyocaulus species from cattle, roe deer and moose in Sweden: molecular evidence for a new species

Total DNA was isolated from adult lungworms of the genus Dictyocaulus, collected from cattle, moose ( Alces alces) and roe deer ( Capreolus capreolus) in Sweden. The second ribosomal internal transcribed spacer was amplified with PCR, and DNA sequences were determined from nine individual worms that all came from different hosts in order to avoid analysis of siblings. The sequence data obtained were aligned and compared with similar data derived from German lungworm isolates from cattle and fallow deer ( Cervus dama). These analyses clearly showed that specimens of the cattle lungworm, Dictyocaulus viviparus, were almost identical irrespective of their geographical origin. However, when the second internal transcribed spacer sequence of D. viviparus was compared with that of lungworms from moose and roe deer, major differences were noticed. Although lungworms collected from these cervids had identical second internal transcribed spacer sequences, they proved to be genetically different from Dictyocaulus eckerti of German fallow deer, displaying a 66.5% similarity. In an evolutionary tree, inferred by maximum likelihood analysis, the Dictyocaulus species from cattle and wild cervids clustered as compared with Dictyocaulus filaria from sheep. The study has thus demonstrated that A. alces and C. capreolus in Sweden are parasitised with a Dictyocaulus species that is different from D. viviparus and D. eckerti, indicating that we are dealing with a new species in moose and roe deer.

Use of an oxfendazole pulse release bolus in the control of parasitic gastroenteritis and parasitic bronchitis in first-season grazing calves

The efficacy of the oxfendazole pulse release bolus system for the control of parasitic gastroenteritis and parasitic bronchitis in first-season grazing calves was evaluated in Belgium. Twenty-two calves were allocated to two groups. The calves in one group received a bolus at the time of turn out, while the other group remained untreated. The efficacy of the bolus was assessed by comparison of faecal worm egg counts, plasma pepsinogen concentrations, the antibody response to Ostertagia, Cooperia and Dictyocaulus species total plasma protein and albumin concentrations, and weight gains throughout the grazing season and the housing period. The oxfendazole pulse release bolus provided good control of parasitic gastroenteritis dominated by ostertagia. The effects of parasitic gastritis were greatly reduced as shown by the significantly lower values of serum pepsinogen and ostertagia antibody titres. The use of the bolus further reduced the adverse effects of parasitism as indicated by better liveweight gains and normal total plasma protein and albumin concentrations whereas in the untreated control group hypoproteinaemia and hypoalbuminaemia were observed. Most animals exhibited clinical signs of parasitic bronchitis at the end of the grazing season, and the bolus may not adequately control parasitic bronchitis in all cases at all times.

Histopathological findings in the lungs of Scottish red and roe deer.

Histopathology on portions of lung collected from 34 red deer (Cervus elaphus) and 15 roe deer (Capreolus capreolus) between 1977 and 1981 revealed evidence of lungworm infestation in 16 red and 14 roe deer. In the red deer, Dictyocaulus species, and the developmental stages of another parasite, believed to be Elaphostrongylus cervi, were involved. Dictyocaulus also affected the roe deer, but in them the major lesions were associated with protostrongylids. Exudative bronchopneumonia, including two cases of fungal infection, was predominantly a problem of red deer under seven months of age. Between the age of four and seven months, parasites frequently accompanied this change. Other conditions encountered were pulmonary congestion, tuberculosis and granulomata of unknown cause.