First complete large subunit ribosomal RNA sequence and secondary structure for a parasitic nematode: phylogenetic and diagnostic implications

First Molecular Identification and Clinical Presentation of Crenosomosis in a Dog from Slovakia

PURPOSE

Crenosoma vulpis (Dujardin,1845) is a lungworm which has spread worldwide in canines and is associated with upper respiratory infections. In a majority of cases, the infections are accompanied with chronic cough. Diagnosis of lungworms is often underdiagnosed and can be misinterpreted as other respiratory diseases.

METHODS

The Small Animal Clinic of the University Veterinary Hospital admitted an 11-month-old dog presented with persistent cough associated with difficulty in breathing and even asphyxia. Based on clinical symptoms, the patient underwent radiological and bronchoscopic examination. Bronchoscopy revealed the presence of lungworms obturating the branches of the tracheobronchial tree. Larvae were collected by bronchoscopic lavage and subjected to parasitological and molecular examination.

RESULTS

Microscopic detection and morphological identification of the worms removed during the bronchoscopy confirmed the presence of female adult worms. The subsequent molecular characterisation of the mitochondrial (cytochrome c oxidase subunit I gene (cox1) and 12S ribosomal DNA (rDNA)), nuclear (18S rDNA) genes, as well as the analysis of the second internal transcribed spacer (ITS-2) region of the ribosomal DNA, confirmed the Crenosoma vulpis species. Faecal samples were processed using the Baermann method, which confirmed the presence of the larval stage 1 of C. vulpis. The therapy with fenbendazole at a dose of 50 mg/kg of live weight once daily for the period of 7 days was initiated for the patient.

CONCLUSION

This paper presents the first molecularly confirmed clinical case of a Crenosoma vulpis infection in an 11-month-old female dog of the Miniature Schnauzer breed in Slovakia.

MOLECULAR PHYLOGENETIC ANALYSIS OF GYRINICOLA BATRACHIENSIS (NEMATODA: OXYUROIDEA) LENDS SUPPORT TO THE MONOPHYLY OF THE GENUS AND THE RESURRECTION OF GYRINICOLINAE

Gyrinicola Yamaguti, 1938, includes 6 species of oxyurid found within the intestinal tract of numerous, larval, anuran species in Europe, Asia, South America, and North America. The systematic placement and hierarchical treatment of the genus has shifted at least 5 times since its discovery; the group was first considered as its own family (Gyrinicolidae), then treated as a subfamily (Gyrinicolinae) of Cosmocercidae, then as a member of the Pharyngodonidae, followed by movement back to the Cosmocercidae, and finally a recent proposal suggested the resurrection of the Gyrinicolidae. Species in the genus vary widely in the morphology of the uterine tract, a characteristic often used to indicate membership in the genus, as it is tied to the reproductive mode. However, until recently very few genetic data were available to aid in the placement of this unique group of worms, and before this study to the best of our knowledge none existed for the North American species. To examine the monophyly and placement of the Gyrinicola we sampled populations of Gyrinicola batrachiensis across North America and screened them for genetic diversity using nuclear markers 18S and 28S. Phylogenies suggest at least 3 clades exist among the nematodes from North America and that these clades, alongside Gyrinicola japonica, form a well-supported group within Oxyuroidea. Further representation of Pharyngodonidae from other vertebrate classes may help clarify the relationship of this historical grouping to other members of the Oxyuroidea.

Cystidicola farionis, a Swim Bladder Parasite of European Smelt: Characterization of the Nematode Trehalose Strategy

The molecular identification of Cystidicola farionis (a swim bladder nematode of European smelt from the Vistula Lagoon in Poland) was performed. Their prevalence level was determined, and changes in the trehalose synthesis pathway in larvae and adult nematodes were demonstrated. The trehalose level was almost four times higher in adult nematodes than in larvae. In contrast, the activity of both enzymes (trehalose 6-phosphate synthase, TPS and trehalose 6-phosphate phosphatase, TPP) involved in the synthesis of trehalose was higher in larvae than in adults under optimal conditions. The optimum pH for TPS isolated from larvae and adults was pH 7.0. The optimum pH for TPP from larvae and adults was pH 7.0 and pH 8.0, respectively. The optimal temperature was 20 °C, and Mg2+ ions were an activator for trehalose-synthetizing enzymes from both sources. Enzymes isolated from adult nematodes were less susceptible to divalent ion chelator and inorganic phosphate than larval enzymes. The dynamic transformation of trehalose in the nematode developing inside the swim bladder of the smelt appears to be an important metabolic pathway in the nematode survival strategy. These studies are aimed at a better understanding of the issue of the metabolic adaptation of parasites, which, in the future, may indirectly contribute to the elimination of the parasite from aquacultures, which will impact public health.

Boehmiella wilsoni (Nematoda, Heligmosomoidea, Boehmiellidae fam. nov.), found in Amazonian rodents

The genus Boehmiella was initially described as a member of the family Trichostrongylidae. Subsequently, it was assigned to the subfamily Haemonchinae in the family Haemonchidae. We analyzed parasites of spiny tree-rats, Mesomys hispidus, collected in the Amazon rainforest, which were identified as B. wilsoni based on integrative taxonomy. Using morphology, morphometry, and scanning electron microscopy (SEM), we added new data to the original description of the species. We also inferred phylogenetic hypotheses for its relationships within the Trichostrongylina, based on partial nuclear 18S and 28S rRNA genes, through Maximum Likelihood and Bayesian analyses. In conclusion, B. wilsoni does not belong to the family Haemonchidae, nor is it closely related to any other trichostrongylin family, and therefore, we propose the establishment of a new family, Boehmiellidae fam. nov., to which the genus Boehmiella is allocated.

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Helminth found in arboreal rodent of the Amazon region, with description of new host, new geographical distribution, new taxonomic data, and proposal of a new family to allocate the genus according to molecular and morphological analyses.

Development of a multiplex qPCR-based approach for the diagnosis of Dirofilaria immitis, D. repens and Acanthocheilonema reconditum

Background

Dirofilaria immitis, D. repens and Acanthocheilonema reconditum are the main causative agents of zoonotic canine filariosis.

Methods

We developed a combined multiplex approach for filaria and Wolbachia detection using the 28S-based pan-filarial and 16S-based pan-Wolbachia qPCRs, respectively, involving a fast typing method of positive samples using triplex qPCR targeting A. reconditum, D. immitis and D. repens, and a duplex qPCR targeting Wolbachia of D. immitis and D. repens. The approach was complemented by a duplex qPCR for the differential diagnosis of heartworms (D. immitis and Angiostrongylus vasorum) and pan-filarial cox1 and pan-Wolbachia ftsZ PCRs to identify other filarial parasites and their Wolbachia, respectively. A total of 168 canine blood and sera samples were used to validate the approach. Spearmanʼs correlation was used to assess the association between filarial species and the strain of Wolbachia. Positive samples for both the heartworm antigen-test after heating sera and at least one DNA-positive for D. immitis and its Wolbachia were considered true positive for heartworm infection. Indeed, the presence of D. repens DNA or that of its Wolbachia as well as A. reconditum DNA indicates true positive infections.

Results

The detection limit for Wolbachia and filariae qPCRs ranged from 5 × 10⁻¹ to 1.5 × 10⁻⁴ mf/ml of blood. When tested on clinical samples, 29.2% (49/168) tested positive for filariae or Wolbachia DNA. Filarial species and Wolbachia genotypes were identified by the combined multiplex approach from all positive samples. Each species of Dirofilaria was significantly associated with a specific genotype of Wolbachia. Compared to the true positives, the approach showed excellent agreement (k = 0.98–1). Unlike D. immitis DNA, no A. vasorum DNA was detected by the duplex qPCR. The immunochromatographic test for heartworm antigen showed a substantial (k = 0.6) and a weak (k = 0.15) agreements before and after thermal pre-treatment of sera, respectively.

Conclusions

The proposed approach is a reliable tool for the exploration and diagnosis of occult and non-occult canine filariosis. The current diagnosis of heartworm disease based on antigen detection should always be confirmed by qPCR essays. Sera heat pre-treatment is not effective and strongly discouraged.

A New Species of Bidigiticauda (Nematoda: Strongylida) from the Bat Artibeus Planirostris (Chiroptera: Phyllostomidae) in the Atlantic Forest and a Molecular Phylogeny of the Molineid Bat Parasites

The nematode genus Bidigiticauda has 2 species (Bidigiticauda vivipara and Bidigiticauda embryophilum), which are parasites of bats from the Neotropical region. The present paper describes a new species of Bidigiticauda from a male Artibeus planirostris specimen collected in the Pratigi Environmental Protection Area in Bahia state, Brazil. The new species, Bidigiticauda serrafreirei n. sp., differs from B. embryophilum by having longer spicules, rays 5 and 6 arising from a common trunk and bifurcating in its first third, rays 3 and 4 emerging slightly separated from each other, and dorsal rays reaching the margin of the caudal bursa. The new species also differs from B. vivipara by the dorsal ray bifurcating at the extremity of the trunk. A molecular phylogenetic analysis was conducted to determine the evolutionary affinities of Bidigiticauda serrafreirei n. sp. within the Strongylida, which identified a clade that grouped Bidigiticauda with the other members of the Anoplostrongylinae. However, the molineid subfamilies did not group together, indicating that the family Molineidae is polyphyletic. Further analyses, which include additional taxa and genetic markers, should elucidate the complex relationships within the Molineidae, in particular its subfamilies and the evolution of the traits that define these groups.

Genetic variation within the genus Macropostrongyloides (Nematoda: Strongyloidea) from Australian macropodid and vombatid marsupials

The genetic variation and taxonomic status of the four morphologically-defined species of Macropostrongyloides in Australian macropodid and vombatid marsupials were examined using sequence data of the ITS+ region (=first and second internal transcribed spacers, and the 5.8S rRNA gene) of the nuclear ribosomal DNA. The results of the phylogenetic analyses revealed that Ma. baylisi was a species complex consisting of four genetically distinct groups, some of which are host-specific. In addition, Ma. lasiorhini in the common wombat (Vombatus ursinus) did not form a monophyletic clade with Ma. lasiorhini from the southern hairy-nosed wombat (Lasiorhinus latifrons), suggesting the possibility of cryptic (genetically distinct but morphologically similar) species. There was also some genetic divergence between Ma. dissimilis in swamp wallabies (Wallabia bicolor) from different geographical regions. In contrast, there was no genetic divergence among specimens of Ma. yamagutii across its broad geographical range or between host species (i.e. Macropus fuliginosus and M. giganteus). Macropostrongyloides dissimilis represented the sister taxon to Ma. baylisi, Ma. yamagutii and Ma. lasiorhini. Further morphological and molecular studies are required to assess the species complex of Ma. baylisi.

Mammomonogamus nematodes in felid carnivores: a minireview and the first molecular characterization

Five of the 13 known species of Mammomonogamus have been described in members of the family Felidae, including domestic cats, making felids the most frequent hosts of Mammomonogamus. The occurrence of Mammomonogamus in felids is geographically scattered and information on the life cycle and other aspects of infections is lacking. The paucity of data opens the questions on possible conspecificity of some of the described species of Mammomonogamus and on the existence of possible reservoirs for infections in domestic cats in geographically isolated endemic foci of infection. To test such hypotheses, we compared sequences of mitochondrial and nuclear markers obtained from Mammomonogamus adults or eggs collected from domestic cats in three geographically distant localities. Based on morphology, geographic origin and site of infection, the worms examined can be referred to as Mammomonogamus ierei and Mammomonogamus auris. Phylogenetic analyses of both mitochondrial and ribosomal DNA markers showed monophyly of the genus Mammomonogamus and suggested the existence of at least two species in cats. Review of the literature, the existence of several species and the discontinuous geographic distribution of Mammomonogamus infections in domestic cats suggest an historical spillover of infection from wild reservoirs, presumably wild felids.

Diversity of Mammomonogamus (Nematoda: Syngamidae) in large African herbivores

Four species of Mammomonogamus are known from large African herbivores. A recent study demonstrated that a single Mammomonogamus species was shared by both western lowland gorillas (Gorilla gorilla gorilla) and African forest elephants (Loxodonta cyclotis) in Central African Republic, suggesting lower species diversity than previously described in literature. We examined more than 500 fecal samples collected from sympatric African forest elephants, western lowland gorillas, and African forest buffaloes (Syncerus caffer nanus) at four study sites across Central Africa and examined them by coproscopic methods to detect Mammomonogamus eggs, which were found at three of the study sites. Subsequently, sequences of 18S rDNA, 28S rDNA, and cox1 amplified from individual eggs were analyzed. Phylogenetic analyses of both nuclear and mitochondrial DNA revealed two clades: one formed by sequences originating from Gabonese buffaloes and the other comprising gorillas and elephants. The gorilla-elephant clade was further differentiated depending on the locality. We show the existence of at least two distinct species of Mammomonogamus, M. loxodontis in elephants and gorillas and M. nasicola in buffaloes. The available information on Mammomonogamus in African herbivores is reviewed.

Prevalence survey on lungworm (Angiostrongylus vasorum, Crenosoma vulpis, Eucoleus aerophilus) infections of wild red foxes (Vulpes vulpes) in central Germany

Background

Angiostrongylus vasorum, Crenosoma vulpis and Eucoleus aerophilus are a source of increasing concern, potentially causing significant pulmonary and severe cardiac/systemic diseases in domestic dogs and wild canids, especially red foxes (Vulpes vulpes). To investigate the prevalence and geographical distribution of these parasites in central Germany, a total of 569 foxes were examined by dissection.

Methods

Pluck (heart and lung) and faecal samples of red foxes were collected from three regions of Germany. Lungs, hearts and adjacent vessels were processed for adult nematode detection. Parasitological diagnoses of faecal samples were performed by SAF technique, Giardia- and Cryptosporidium-Coproantigen-ELISAs and by a duplex copro-PCR for the detection of A. vasorum and C. vulpis DNA.

Results

Foxes originated from three Federal States of central Germany: Thuringia (n = 359); Rhineland-Palatinate (n = 121) and Hesse (n = 89). High prevalences for all three nematodes were detected, with E. aerophilus (69.4%; 395/569), followed by C. vulpis (32.3%; 184/569) and A. vasorum (14.1%; 80/569). In case of A. vasorum, prevalences varied significantly between Federal States, with the highest prevalence of 27.3% in Rhineland-Palatinate, followed by 19.1% and 8.4% in Hesse and Thuringia, respectively. The presence of A. vasorum in fox populations showed a rather patchy distribution, increasing from north-eastern to south-western regions. Analyses on C. vulpis revealed prevalences of 35.1%, 30.3% and 25.6% (Thuringia, Hesse and Rhineland-Palatinate, respectively). The most prevalent lungworm nematode was E. aerophilus, with a prevalence of 75.2%, 71.9% and 66.9% (Rhineland-Palatinate, Hesse and Thuringia, respectively) and an almost area-wide equal distribution. Significant differences for single parasite prevalences within geographical regions of the Federal States could be detected whilst no correlation between age or gender and parasite occurrence was estimated. Weak seasonality for the winter months for A. vasorum, stronger correlation to spring and late summer for C. vulpis and no correlation to any season for E. aerophilus were detected. The method of dissection revealed a significantly higher sensitivity for C. vulpis when compared with the results of the duplex copro-PCR.

Conclusions

A sylvatic cycle was confirmed for all three lungworm nematodes in the examined area. The prevalences for all three lungworm nematodes are some of the highest recorded so far in German foxes. The data suggest that A. vasorum might be spreading from south-western to north-eastern parts of Germany.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2672-4) contains supplementary material, which is available to authorized users.

Alloionema similis n. sp., a genetically divergent sibling species of A. appendiculatum Schneider, 1859 (Rhabditida: Alloionematidae) from invasive slugs in California, USA

A new species of Alloionema Schneider, 1859, A. similis n. sp., and the known species A. appendiculatum Schneider, 1859 were isolated from cadavers of invasive slugs in California. Both species are described based on morphology, morphometrics and molecular data. Alloionema similis n. sp. is morphologically very similar to A. appendiculatum but can be distinguished by a more posterior position of the excretory pore in the Kleinform females and longer tail in the Kleinform males. Substantial differences between the two species are, however, found in both 18S and 28S rDNA sequences. Sequence analysis revealed unambiguous autapomorphies in nucleotide sequence and secondary structure of rRNA genes, separating A. appendiculatum and A. similis n. sp. Molecular phylogenies were inferred from concatenated secondary-structure based multiple sequence alignments of nearly complete 18S and the D1-D3 domains of the 28S rRNA genes. Phylogenetic analyses placed these two species as sister taxa in a monophyletic clade, separately from Neoalloionema tricaudatum Ivanova, Pham Van Luc & Spiridonov, 2016 and N. indicum Nermuť, Půža & Mráček, 2016.

Comparison of three methods for the detection of Angiostrongylus vasorum in the final host

Angiostrongylosis is potentially fatal parasitic nematode infection affecting dogs which can be difficult to diagnose. In recent years several microscopical, serological and molecular detection methods have been developed, however there are few studies that have compared the relative performance of these methods. Screening necropsy material from an opportunistic sample of 140 foxes (82 of which were considered to be infected with Angiostrongylus vasorum), indicated sensitivities of 84.1% for dissection and visual examination of plucks, 69.5% for nested PCR of an 18S rRNA fragment and 76.8% for a canine A. vasorum antigen detection test (IDEXX Angio Detect) of tissue fluid samples respectively. Agreement between the tests ranged from 45.6 to 79.7%. A novel nested PCR-RFLP for the detection and identification of canid lungworm spp. is described.

Description of Phasmarhabditis californica n. sp. and first report of P. papillosa (Nematoda: Rhabditidae) from invasive slugs in the USA

A new species ofPhasmarhabditisand the known speciesP. papillosawere isolated from cadavers of invasive slugs in California.Phasmarhabditis papillosais the type of the genus and has not previously been reported from the Americas. Both species are characterised based on morphology, morphometrics and molecular data. Molecular phylogenies were inferred from concatenated DNA sequence alignments of nearly complete SSU and the D2-D3 domains of the LSU rDNA.Phasmarhabditis californican. sp. is characterised by a robust body, mature egg-laying specimens almost spindle-shaped when relaxed, 1.5 (1.3-1.8) mm long, tapering to a bluntly rounded anterior end with stoma about as long as lip region diam., six inner labial papillae and four outer cephalic papillae, pharynx with rounded to pyriform basal bulb, vulva located halfway along the body, hermaphroditic, didelphic, amphidelphic, and short, conoid tail constricted at one-third its length with prominent phasmids. Not a single male was found among five strains.Phasmarhabditis papillosais gonochoristic and has a longer isthmus, pyriform basal bulb and longer, dome-shaped spicate female tail constricted halfway along its length. Sequence analysis revealed unambiguous autapomorphies forP. papillosaandP. californican. sp. Phylogenetic analyses placed these two species in a monophyletic clade comprisingPhasmarhabditisspecies and other gastropod-parasitic taxa. Morphology, genetic distance, reproductive strategy and nucleotide autapomorphies support the new taxon.

Hemoparasites in a wild primate: Infection patterns suggest interaction of Plasmodium and Babesia in a lemur species

Hemoparasites can cause serious morbidity in humans and animals and often involve wildlife reservoirs. Understanding patterns of hemoparasite infections in natural populations can therefore inform about emerging disease risks, especially in the light of climate change and human disruption of natural ecosystems. We investigated the effects of host age, sex, host group size and season on infection patterns of Plasmodium sp., Babesia sp. and filarial nematodes in a population of wild Malagasy primates, Verreaux's sifakas (Propithecus verreauxi), as well as the effects of these infections on hematological variables. We tested 45 blood samples from 36 individuals and identified two species of Plasmodium, one species of Babesia and two species of filarial nematodes. Plasmodium spp. and Babesia sp. infections showed opposite patterns of age-dependency, with babesiosis being prevalent among young animals, while older animals were infected with Plasmodium sp. In addition, Babesia sp. infection was a statistically significant negative predictor of Plasmodium sp. infection. These results suggest that Plasmodium and Babesia parasites may interact within the host, either through cross-immunity or via resource competition, so that Plasmodium infections can only establish after babesiosis has resolved. We found no effects of host sex, host group size and season on hemoparasite infections. Infections showed high prevalences and did not influence hematological variables. This preliminary evidence supports the impression that the hosts and parasites considered in this study appear to be well-adapted to each other, resulting in persistent infections with low pathogenic and probably low zoonotic potential. Our results illustrate the crucial role of biodiversity in host-parasite relationships, specifically how within-host pathogen diversity may regulate the abundance of parasites.

Parasitic nematode communities of the red kangaroo, Macropus rufus: richness and structuring in captive systems

Captive management practices have the potential to drastically alter pre-existing host-parasite relationships. This can have profound implications for the health and productivity of threatened species in captivity, even in the absence of clinical symptoms of disease. Maximising the success of captive breeding programmes requires a detailed knowledge of anthropogenic influences on the structure of parasite assemblages in captive systems. In this study, we employed two high-throughput molecular techniques to characterise the parasitic nematode (suborder Strongylida) communities of the red kangaroo, Macropus rufus, across seven captive sites. The first was terminal restriction fragment length polymorphism (T-RFLP) analysis of a region of rDNA encompassing the internal transcribed spacers 1 (ITS1), the 5.8S rRNA gene and the internal transcribed spacer 2 (ITS2). The second was Illumina MiSeq next-generation sequencing of the ITS2 region. The prevalence, intensity of infection, taxonomic composition and comparative structure of strongylid nematode assemblages was assessed at each location. Prevalence (P = <0.001) and mean infection intensity (df = 6, F = 17.494, P = <0.001) differed significantly between the seven captive sites. Significant levels of parasite community structure were observed (ANOSIM, P = 0.01), with most of the variation being distributed within, rather than between, captive sites. The range of nematode taxa that occurred in captive red kangaroos appeared to differ from that of wild conspecifics, with representatives of the genus Cloacina, a dominant nematode parasite of the macropodid forestomach, being detected at only two of the seven study sites. This study also provides the first evidence for the presence of the genus Trichostrongylus in a macropodid marsupial. Our results demonstrate that contemporary species management practices may exert a profound influence on the structure of parasite communities in captive systems.

Mutation scanning analysis of genetic variation within and among Echinococcus species: implications and future prospects

Adult tapeworms of the genus Echinococcus (family Taeniidae) occur in the small intestines of carnivorous definitive hosts and are transmitted to particular intermediate mammalian hosts, in which they develop as fluid-filled larvae (cysts) in internal organs (usually lung and liver), causing the disease echinococcosis. Echinococcus species are of major medical importance and also cause losses to the meat and livestock industries, mainly due to the condemnation of infected offal. Decisions regarding the treatment and control of echinococcosis rely on the accurate identification of species and population variants (strains). Conventional, phenetic methods for specific identification have some significant limitations. Despite advances in the development of molecular tools, there has been limited application of mutation scanning methods to species of Echinococcus. Here, we briefly review key genetic markers used for the identification of Echinococcus species and techniques for the analysis of genetic variation within and among populations, and the diagnosis of echinococcosis. We also discuss the benefits of utilizing mutation scanning approaches to elucidate the population genetics and epidemiology of Echinococcus species. These benefits are likely to become more evident following the complete characterization of the genomes of E. granulosus and E. multilocularis.

Utility of divergent domains of 28S ribosomal RNA in species discrimination of paramphistomes (Trematoda: Digenea: Paramphistomoidea)

Among the digenetic trematodes, paramphistomes are known to be the causative agent of "amphistomiasis" or the stomach fluke disease of domestic and wild animals, mainly ruminants. The use of 28S (divergent domains) and 18S rRNA for phylogenetic inference is significantly warranted for these flukes since it is as yet limited to merely the exploration of the second internal transcribed spacer (ITS2) region. The present study intended to explore the divergent domains (D1-D3) of 28S rRNA and simultaneously equate the phylogenetic information with 18S rRNA in paramphistomes. Divergence of the 28S rRNA domains was evident amongst the divergent (D) domains, where D1 domain emerged as the most variable and D2, the most robust domain, since the latter could provide a higher resolution of the species. D2 was the only domain that comprised compensatory mutations in the helices of its structural constraints; this domain is thus well suited for species distinction and may be considered a potential DNA barcode complementary to mitochondrial DNA. 28S (D1 + D2 + D3) rRNA provided a significant resolution of the taxa corroborating with the taxonomy of these flukes and thus proved to be more robust as a phylogenetic marker for lower levels than 18S rRNA. Phylogenetic inferences of paramphitomes are still scarcely explored; additional data from other taxa belonging to this family may estimate better the biodiversity of these flukes.

Diversity and prevalence of metastrongyloid nematodes infecting the red panda (Ailurus fulgens) in European zoos

Metastrongyloid induced pneumonia has been described sporadically in the red panda (Ailurus fulgens). Early descriptions in pandas recently imported to the USA from China involved parasites morphologically similar to Angiostrongylus spp. and Crenosomatidae. More recently, four cases of severe verminous pneumonia associated with Angiostrongylus vasorum have been reported from European zoos. A coprological survey of the red panda population within European zoos was conducted in 2008. Faecal samples from 115 pandas originating from 54 zoos were collected on 3 consecutive days. Using Baermann technique, 40 animals (35%) from 20 zoos (37%) were found to shed metastrongyloid first stage larvae (L(1)). Based on their morphology and size, the L(1) observed could be divided into three morphologically distinct types: (1) a Crenosoma sp. type (n=5, overall prevalence: 4.3%), (2) an A. vasorum type (n=3, 2.6%), and (3) an unidentified metastrongyloid species, similar to, but morphologically distinct from A. vasorum (n=32, 27.8%). Further confirmation of species identification was provided by PCR amplification and sequencing of the 18S rRNA gene, which confirmed three different species. The novel Crenosoma species was most genetically analogous to Crenosoma mephitidis and the unidentified metastrongyloid species was most similar to Stenurus minor and Torynurus convulutus. Routine and quarantine health care of red pandas in captivity should take account of the risk of Angiostrongylus and Crenosoma infection in endemic areas, but should also be cognisant of the widespread presence of an apparently less pathogenic species of lungworm. The identity of the two potentially novel species is subject to further work.

Analysis of genetic variation in Globocephaloides populations from macropodid marsupials using a mutation scanning-based approach

Three species of Globocephaloides, parasitic nematodes occurring in macropodid marsupials in different areas of Australia, were characterized by the sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA. Samples were subjected to PCR-coupled SSCP analysis and targeted sequencing, in order to assess genetic variation within and among individuals from different host species. Both SSCP and sequence data supported the current classification of morphospecies. Contrary to a previous hypothesis that cryptic species exist within the Globocephaloides trifidospicularis "complex", no or minor (0.2%) variation was detected among individuals from different hosts or geographical origins. Within G. macropodis populations, there was a consistent difference in both the ITS-1 (5.2%) and ITS-2 (7.1%) sequences between individuals derived from Macropus agilis and those from Macropus dorsalis. Although the results suggested that G. macropodis from each host species represented sibling species, future morphological study of individuals representing each G. macropodis genotype is warranted to provide further support for this hypothesis. (Nucleotide sequence data have been deposited in the GenBank database under accession nos. GQ131400-GQ131409.).

Pneumonia from Angiostrongylus vasorum infection in a red panda (Ailurus fulgens fulgens)

A 9-year-old, male, captive red panda (Ailurus fulgens fulgens) in an urban zoo in the United Kingdom presented with respiratory distress and weight loss. The animal was euthanatized, and a postmortem examination was performed. The lungs were diffusely consolidated with extensive mineralization. Microscopically, there was extensive obliteration of normal pulmonary architecture by sheets and coalescing nodules of partially mineralized fibrous tissue and granulomatous inflammation centered on large numbers of nematode larvae and eggs. First stage nematode larvae were isolated from lung tissue and were characterized as Angiostrongylus vasorum on the basis of their morphology and sequencing of the 18S ribosomal RNA gene and the entire second internal transcribed spacer. Although A. vasorum has previously been reported in red pandas in a zoological collection in Denmark, this study is the first reported case in the United Kingdom and occurs against a background of geographical spread and increased incidence of disease in domestic and wild canids. Angiostrongylus vasorum should be considered a differential diagnosis for respiratory disease in the red panda and taken into account when planning parasite and pest control programs for zoological collections.

Disseminated angiostrongylosis with fatal cerebral haemorrhages in two dogs in Germany: a clinical case study

Canine angiostrongylosis is a nematode infection in domestic dogs and wild carnivores. Few single case reports describing the occurrence of this disease in Germany exist and until recently angiostrongylosis has not been considered endemic in this country. The present report focuses on clinical, pathological and parasitological findings in two cases of fatal disseminated canine angiostrongylosis associated with multifocal haemorrhages in the central nervous system. Both animals, which lived in Germany, presented with rapidly progressive neurological signs including depression, ataxia, unilateral central blindness and epileptic seizures. Blood work revealed grossly elevated D-dimers and mild thrombocytopenia. Both animals were subsequently euthanised due to progressive clinical aggravation. Necropsy showed cerebral and lung haemorrhages in both animals. Multiple sections of nematode larvae consistent with Angiostrongylus vasorum were identified on histopathological sections of the brain, heart, kidney and lung in both animals and a predominantly granulomatous inflammation with the occurrence of multinucleated giant cells was observed. Adult nematodes were found in the larger lung arteries of one dog and Angiostrongylus infection was subsequently confirmed by PCR-analysis and sequencing in both dogs. A. vasorum larvae were not detected by faecal Baermann examination performed in one of the dogs. It was concluded that canine angiostrongylosis should be considered as differential diagnosis in dogs in Germany, even if faecal examination is negative. There is currently still a lack of studies investigating the occurrence of angiostrongylosis in dogs and intermediate hosts in Germany which would be necessary to survey the endemic realities of this disease.

Informative characteristics of 12 divergent domains in complete large subunit rDNA sequences from the harmful dinoflagellate genus, Alexandrium (Dinophyceae)

The genus Alexandrium includes organisms of interest, both for the study of dinoflagellate evolution and for their impacts as toxic algae affecting human health and fisheries. Only partial large subunit (LSU) rDNA sequences of Alexandrium and other dinoflagellates are available, although they contain much genetic information. Here, we report complete LSU rDNA sequences from 11 strains of Alexandrium, including Alexandrium affine, Alexandrium catenella, Alexandrium fundyense, Alexandrium minutum, and Alexandrium tamarense, and discuss their segmented domains and structure. Putative LSU rRNA coding regions were recorded to be around 3,400 bp long. Their GC content (about 43.7%) is among the lowest when compared with other organisms. Furthermore, no AT-rich regions were found in Alexandrium LSU rDNA, although a low GC content was recorded within the LSU rDNA. No intron-like sequences were found. The secondary structure of the LSU rDNA and parsimony analyses showed that most variation in LSU rDNA is found in the divergent (D) domains with the D2 region being the most informative. This high D domain variability can allow members of the diverse Alexandrium genus to be categorized at the species level. In addition, phylogenetic analysis of the alveolate group using the complete LSU sequences strongly supported previous findings that the dinoflagellates and apicomplexans form a clade.

Complete sequence and secondary structure of the large subunit ribosomal RNA from the harmful unarmored dinoflagellate Akashiwo sanguinea

This is the first report of the complete DNA sequence of the gene encoding the ribosomal large subunit (LSU rDNA, 3336 bp) from the naked gymnodinioid dinoflagellate Akashiwo sanguinea. No introns were found in the LSU rDNA coding region and secondary structures were predicted for both the LSU and 5.8S rRNAs. The predicted LSU structure showed most of the features seen in the consensus secondary structure model proposed for the eukaryotic nuclear LSU rRNAs. However, six helices (C1_1, C1_2, C1_3, D10, D20_1 and H1_2) are not present in the A. sanguinea LSU structure. Particularly, the C branch area (or D2 domain), was extremely reduced compared to the eukaryotic consensus sequence due to nucleotide deletion. Phylogenetic resolution against 12 divergent (D) domains and cores in LSU rDNA showed that the D1, D2 and D12 domains were highly variable and could be used as genetic markers within low taxonomic levels, particularly in the gymnodinioid complex.

Nucleotide alterations in the D3 domain of the large subunit of ribosomal DNA among 21 species of equine strongyle

The expansion segments or divergent (D) domains in the large subunit (LSU) of the ribosomal DNA have been suggested as genetic markers for taxonomic and/or phylogenetic studies of parasites. In the present study, we assessed the degree of sequence variation in the D3 domain and flanking core regions of the LSU for 21 species of equine strongyles (Strongylida: Strongylidae) and determined which positions in the secondary structure of the LSU were associated with the nucleotide alterations. No intraspecific sequence variation was detected in 17 species, for which multiple individual worms were available. Mutations in sequence among species were detected at 19 nucleotide positions, most of which were located in the D3 domain. Fifteen alterations were transitions, three were transversions and one represented a site of multiple mutations. In relation to the secondary structure element of D3, 26% of these mutations were located in unpaired regions (i.e., end of loops, or in bulges of helices) and thus did not appear to alter the pairing arrangement in the helices of the secondary structure. Many of the other mutations represented partial or complete compensatory base pair changes. The magnitude of interspecific nucleotide variation in the D3 domain (0-4%) was considerably less than that recorded for some other nematode groups (enoplids and thelastomatoids), indicating that this region alone is of limited value for taxonomic and phylogenetic studies for strongyles of equids but is interesting in relation to the evolution of ribosomal DNA.

Application of the secondary structure model of rRNA for phylogeny: D2-D3 expansion segments of the LSU gene of plant-parasitic nematodes from the family Hoplolaimidae Filipjev, 1934

Knowledge of rRNA structure is increasingly important to assist phylogenetic analysis through reconstructing optimal alignment, utilizing molecule features as an additional source of data and refining appropriate models of evolution of the molecule. We describe a procedure of optimization for alignment and a new coding method for nucleotide sequence data using secondary structure models of the D2 and D3 expansion fragments of the LSU-rRNA gene reconstructed for fifteen nematode species of the agriculturally important and diverse family Hoplolaimidae, order Tylenchida. Using secondary structure information we converted the original sequence data into twenty-eight symbol codes and submitted the transformed data to maximum parsimony analysis. We also applied the original sequence data set for Bayesian inference. This used the doublet model with sixteen states of nucleotide doublets for the stem region and the standard model of DNA substitution with four nucleotide states for loops and bulges. By this approach, we demonstrate that using structural information for phylogenetic analyses led to trees with lower resolved relationships between clades and likely eliminated some artefactual support for misinterpreted relationships, such as paraphyly of Helicotylenchus or Rotylenchus. This study as well as future phylogenetic analyses is herein supported by the development of an on-line database, NEMrRNA, for rRNA molecules in a structural format for nematodes. We also have developed a new computer program, RNAstat, for calculation of nucleotide statistics designed and proposed for phylogenetic studies.

Identification and characterization of the threadworm, Strongyloides procyonis, from feral raccoons (Procyon lotor) in Japan

Strongyloides procyonis Little, 1966 was detected about 45 years ago in raccoons (Procyon lotor) of southern Louisiana, U.S.A., and was demonstrated experimentally to cause creeping eruption and a short-lived intestinal infection in a healthy human volunteer. After its description and demonstration of its pathogenicity in humans, S. procyonis has not been found in raccoons in North America despite repeated surveys. During a survey on feral raccoons in Japan, S. procyonis parasitic females were identified in 66 (28.3%) of 233 raccoons collected between May 2004 and January 2005. The number of parasitic females recovered from individual raccoons was 1-197 (geomean, 3.2). Both the morphological features and the nucleotide sequences of the small and large subunit ribosomal RNA genes (SSU/LSU rDNA) of S. procyonis closely resembled those of zoonotic Strongyloides stercoralis. The sequences of internal transcribed spacer (ITS)1 and 28S rDNA could differentiate clearly these 2 species. Awareness of S. procyonis in raccoons in North America and other places worldwide where raccoons are introduced and naturalized is important to assess the epidemiological significance of this potentially zoonotic helminth species.

The evolutionary origins of nematodes within the order Strongylida are related to predilection sites within hosts

The evolutionary relationships of the different groups of nematodes within the order Strongylida based on morphological data have been speculative and the subject of conjecture. In this paper, we present a multigene phylogenetic analysis, using sequence data of the 18S and 28S ribosomal RNA genes from representatives of all four suborders and seven superfamilies of the Strongylida, to test existing hypotheses proposed for the relationships of the suborders based on morphological data sets. The results obtained demonstrated that the Strongylida is a monophyletic assemblage, with only the Metastrongylina (but not the other suborders) forming a distinct monophyletic clade. We show that, in contrast to all previous hypotheses, one major lineage comprises taxa which occur exclusively in the pulmonary, circulatory or nervous systems of marsupial and eutherian mammals, whereas a second lineage comprises species occurring in the gastrointestinal tracts or perirenal tissues of vertebrates, or in the lungs of birds. The findings suggest that the predilection site of adult nematodes and host type reflect the evolutionary origin of the different taxonomic groups within the Strongylida.

Molecular characterization of Thelastomatoidea (Nematoda: Oxyurida) from cockroaches in Australia

A molecular approach was used to genetically characterize 5 species (Aoruroides queenslandensis, Blattophila sphaerolaima, Cordonicola gibsoni, Desmicola ornata and Leidynemella fusiformis) belonging to the superfamily Thelastomatoidea (Nematoda: Oxyurida), a group of pinworms that parasitizes terrestrial arthropods. The D3 domain of the large subunit of nuclear ribosomal RNA (LSU) was sequenced for individual specimens, and the analysis of the sequence data allowed the genetic relationships of the 5 species to be studied. The sequence variation in the D3 domain within individual species (0-1.8%) was significantly less than the differences among species (4.3-12.4%). Phylogenetic analyses, using maximum parsimony, maximum likelihood, and neighbour-joining, tree-building methods, established relationships among the 5 species of Thelastomatoidea and Oxyuris equi (a species of the order Oxyurida). The molecular approach employed provides the prospect for developing DNA tools for the specific identification of the Thelastomatoidea, irrespective of developmental stage and sex, as a basis for systematic, ecological and/or population genetic investigations of members within this superfamily.

Genetic analysis of Trichinella populations by ‘cold’ single-strand conformation polymorphism analysis

A non-isotopic single-strand conformation polymorphism ('cold' SSCP) technique has been assessed for the analysis of sequence variability in the expansion segment 5 (ES5) of domain IV and the D3 domain of nuclear ribosomal DNA within and/or among isolates and individual muscle (first-stage) larvae representing all currently recognized species/genotypes of Trichinella. Data are consistent with the ability of cold SSCP to identify intra-specific as well as inter-specific variability among Trichinella genotypes. The cold SSCP approach should be applicable to a range of other genetic markers for comparative studies of Trichinella populations globally.

Nonisotopic single-strand conformation polymorphism analysis of sequence variability in ribosomal DNA expansion segments within the genusTrichinella (Nematoda: Adenophorea)

A nonisotopic single-strand conformation polymorphism (SSCP) approach was employed to 'fingerprint' sequence variability in the expansion segment 5 (ES5) of domain IV and the D3 domain of nuclear ribosomal DNA within and/or among isolates and individual muscle (first-stage) larvae representing all currently recognized species/genotypes of Trichinella. In addition, phylogenetic analyses of the D3 sequence data set, employing three different tree-building algorithms, examined the relationships among all of them. These analyses showed strong support that the encapsulated species T. spiralis and T. nelsoni formed a group to the exclusion of the other encapsulated species T. britovi and its related genotypes Trichinella T8 and T9 and T. murrelli, and T. nativa and Trichinella T6, and strong support that T. nativa and Trichinella T6 grouped together. Also, these eight encapsulated members grouped to the exclusion of the nonencapsulated species T. papuae and T. zimbabwensis and the three representatives of T. pseudospiralis investigated. The findings showed that nonencapsulated species constitute a complex group which is distinct from the encapsulated species and supported the current hypothesis that encapsulated Trichinella group external to the nonencapsulated forms, in accordance with independent biological and biochemical data sets.

Molecular dissection of the rDNA array and of the 5S rDNA gene in Meloidogyne artiellia: phylogenetic and diagnostic implications

The sequence of a 13.423 nucleotide genomic fragment has been determined for the plant parasitic nematode Meloidogyne artiellia. It contains an entire rDNA cluster, the bordering intergenic regions and portions of the flanking coding regions. The sequence analysis of the rDNA repeats suggests homogeneity in M. artiellia, thus providing a further indication of the usefulness of these genes for the diagnostic identification of this species. The comparison of the secondary structures of the internal transcribed spacer 2 region in several Meloidogyne species indicates that RNA folding predictions can be used as a tool of potential diagnostic relevance. The other ribosomal gene, 5S rDNA, has been demonstrated to be functional and located near the trans-spliced leader sequences, in the same arrangement found in the distantly related nematode Caenorhabditis elegans but never in other Meloidogyne thus providing species-specific markers for the identification of several Thylenchida parasitic nematodes.