Gastrointestinal Strongyles in Wild Ruminants

Parasitologists have long studied helminth infections in wildlife species and have documented the existence of many organisms from a diversity of mammalian hosts. With this accumulation of information has come improved understanding of the significance of these organisms and the diseases they produce in their mammalian hosts. Some of the most notable examples include the metastrongyloid lungworms, Trichinella spiralis, and Elaeophora schneideri, which are covered separately in this volume. It is, however, for the group of parasites referred to as gastrointestinal nematodes that we have accumulated the most data. Only recently has progress been made in determining the significance of these strongylate nematodes with respect to their potential impact on the morbidity and mortality of the ruminants that they infect. The accumulation of information on diseases of wild animals into a single combined volume has been slow, but progress has coincided with the proliferation of data for host and parasite interactions. Numerous references including Alaskan Wildlife Diseases (Dieterich 1981), Manual of Common Wildlife Diseases in Colorado (Adrian 1981), Field Manual of Wildlife Diseases in the Southeastern United States (Davidson and Nettles 1988), Zoo and Wildlife Medicine (Fowler 1993), and the previous editions of Parasitic Diseases of Wild Mammals (Davis and Anderson 1971) have all made significant contributions to our knowledge. Beyond North America, Dunn (1969) and Govorka et al. (1988) provided excellent compilations on the helminths in wild ruminants. In the 1971 printing of Parasitic Diseases of Mammals, however, there was no general coverage of gastrointestinal nematodes, and only T. spiralis was addressed. Herein, we present the first synoptic review of the strongylate nematodes that occur in the gastrointestinal system of wild ruminants from North America

Reassignment of \u3ci\u3eLamanema\u3c/i\u3e from Nematodirinae to Molineinae (Nematoda: Trichostrongyloidea) (Research Notes)

The monospecific Lamanema historically has been assigned to the Nematodirinae within the Molineidae. Inconsistencies in morphological characters, within a phylogenetic context for Nematodirinae, led to a re-evaluation of the putative relationships and taxonomic placement of Lamanema. Among 7 putative synapomorphies for Nematodirinae, Lamanema possesses only one, large eggs. Large eggs, sporadically present in phylogenetically disparate taxa of trichostrongyles, are equivocal with respect to placement of Lamanema; it is considered that possession of this single homoplasious character alone is insufficient justification to retain the genus in Nematodirinae. Affinities with the Trichostrongylidae (Cooperiinae or Haemonchinae) have also been proposed; however, Lamanema possess neither of two synapomorphies that diagnose monophyly of the family. Lamanema is retained in the Molineidae and transferred to the Molineinae as it possesses all characters of the family as currently defined. The origin of Lamanema represents a secondary colonization of ruminants by molineids and provides no context for elucidating the history of the Nematodirinae and Nematodirus

The Epizootiology of gastrointestinal nematodes of cattle in selected areas of Oregon

A study was initiated to 1) determine which species of gastrointestinal nematodes are present in cattle in selected areas of Oregon, 2) examine the seasonal abundance of these nematodes as an indicator of periods of transmission and 3) determine at what season developmental inhibition occurs in the major genera of nematodes encountered. Four study sites representative of the major geographic regions within the state of Oregon were chosen: Corvallis, Langlois, near Fort Rock and southeast of Klamath Falls on the Oregon-California border. Eight sets of 3-4 tracer calves each were introduced onto pasture at each site over a 2 year period. Time of turnout onto pasture was dictated by the grazing season and corresponded to late spring, mid summer, late fall and late winter. At Corvallis, a distinct seasonality in parasite transmission (as indicated by nematode abundance) was evident with peaks occurring during the fall and winter. At Langlois, transmission was fairly constant throughout the year. However, no discernible patterns were evident at either Klamath Falls or Fort Rock. A total of eight genera of nematodes were encountered during the study. Four (Ostertagia. Cooperia. Nematodirus and Trichostrongylus) were present at all study sites and were the most common genera at each. Trichuris was found at all sites except Klamath Falls. Oesophagostomum was present in tracers only from Langlois and Corvallis while Haemonchus was found only at Klamath Falls and Fort Rock. Capillaria was only present at Klamath Falls. Where possible, specific transmission patterns for Nematodirus. Cooperia. and Ostertagia were determined for each site. Nematodirus was transmitted fairly steadily at both Langlois and Corvallis but was quite variable at Fort Rock. Developmental arrest was detected in this genus at all study sites during the fall and/or winter. Cooperia exhibited the most seasonally defined pattern of transmission with peak abundances during the fall and winter at Langlois, Corvallis and Klamath Falls. Hypobiotic larvae of Cooperia were present during the fall and/or winter only at Langlois and Corvallis. Peak transmission of Ostertagia at Langlois and Corvallis occurred during the fall and winter. At Fort Rock, transmission was lowest in the fall and increased in the winter. Hypobiotic larvae were evident in the fall and winter at Corvallis, Fort Rock and Klamath Falls. These data suggest Type II ostertagiasis may occur in late winter through spring in these areas. Hypobiotic larvae of Ostertagia were not detected at Langlois. The lack of appropriate environmental stimuli is one possible explanation for the apparent lack of hypobiosis at that site

Synlophe of \u3ci\u3eNematodirus neotoma\u3c/i\u3e (Trichostrongyloidea)

The synlophe of Nematodirus neotoma from Neotoma spp. is characterized. The cervical synlophe is composed of 30-32 and 36-42 ridges in males and females, respectively. Of these, 14 and 20-22 ridges are continuous in the cervical zone and extend to the base of the cephalic expansion. Six pairs of lateral ridges are discontinuous but extend greater than one-third the length of the cervical region. In both males and females, the number of ridges increases posteriad, terminating near the bursa in the male, and extending the entire length of the body in the female. The synonymy of N. neotoma and N. tortuosus was confirmed

Late Fall Transmission of \u3ci\u3eNematodirus battus\u3c/i\u3e (Nematoda: Trichostrongyloidea) in Western Oregon

Studies on Nematodirus battusCrofton and Thomas, 1951, have shown a marked seasonality in the pattern of transmission. The life cycle normally involves only one parasitic generation per year. The infective third-stage larvae develop over the summer within eggs deposited on pasture. Eggs are sensitized by low temperatures during fall and winter; larval hatching follows in the presence of adequate moisture and proper osmotic conditions as the temperature rises above 10°C. This set of conditions, conducive to hatching, is regularly present only during spring; thus, hatching of eggs is concentrated into a few weeks during this time. Outbreaks of clinical nematodiriasis are determined by the timing and magnitude of the seasonal hatch of larvae and the presence of young, susceptible lambs. On occasion, deviations from this typical pattern have been reported. Completion of the life cycle has been recorded during other times of the year, particularly in the fall. Larval availability during fall has been attributed to three different mechanisms: (1) eggs hatching within the same year as deposited; (2) eggs deposited during fall, overwintering and hatching the following fall; and (3) eggs hatching in spring, followed by long-term survival of the larvae through the summer

Relationships of \u3ci\u3eNematodirus\u3c/i\u3e Species and \u3ci\u3eNematodirus battus\u3c/i\u3e Isolates (Nematoda: Trichostrongyloidea) Based on Nuclear Ribosomal DNA Sequences

Nuclear ribosomal sequence data from the internal transcribed spacers (ITS-1 and ITS-2), 5.8S subunit, and regions of the 18S and 28S genes were used to investigate sequence diversity among geographic samples of Nematodirus battus, and to infer phylogenetic relationships among Nematodirus species. Phylogenetic analysis of these data yielded strong support for relationships among species, depicting Nematodirus helvetianus and Nematodirus spathiger as sister-taxa and a clade of these two species and Nematodirus filicollis. This tree is consistent with caprine bovids as ancestral hosts, with a subsequent host shift to Bovinae in N. helvetianus. Eleven of 14 N. battus sequences were unique, with 19 variable sites among sequences representing 5 geographic samples. The lowest number of variable nucleotide sites was observed in samples representing apparently recent introductions to the United States and Canada, which is consistent with a population bottleneck concomitant with translocation. Comparison of directly sequenced polymerase chain reaction products and clones revealed evidence for intraindividual variation at some of the sequence sites, and this pattern of variation and that within geographic samples indicates incomplete rDNA repeat homogenization within species. This pattern of variation is not conducive for inferring phylogenetic relationships among sequences representing N. battus or addressing the putative history of introduction

Isoelectric Focusing of Soluble Proteins in the Characterization of Species and Isolates of \u3ci\u3eNematodirus\u3c/i\u3e (Nematoda: Trichostrongyloidea)

Isoelectric focusing was performed on extracts from Nematodirus spathiger, Nematodirus filicollis, Nematodirus helvetianus, and three geographic isolates of Nematodirus battus. Gender-specific differences were noted within species; however, the overall protein profile of each species and isolate was distinct and reproducible and allowed unequivocal differentiation. A coefficient of similarity (Sm) for males of each species and isolate was calculated, and a dendrogram, based on evaluation of Sm by the unweighted pair-group method with arithmetic means, was produced. Although cluster analysis of the three isolates of N. battus indicates the North American and Weybridge isolates are similar, interpretation of the relationships and thus the history of introduction based on these data is equivocal. Isoelectric focusing is a robust method for establishing identity and has great utility in diagnostics. However, in the absence of selective histochemical staining, interpretation of identity and homology for specific bands and banding patterns is problematic, thus limiting the utility of this method for phylogenetic inference

\u3ci\u3eSpiculopteragia spiculoptera\u3c/i\u3e and \u3ci\u3eS. asymmetrica\u3c/i\u3e (Nematoda: Trichostrongyloidea) from Red Deer (\u3ci\u3eCervus elaphus\u3c/i\u3e) in Texas

Specimens of Spiculopteragia spiculoptera and S. asymmetrica were recovered from the abomasa of five of ten naturally infected red deer (Cervus elaphus) in Texas (USA). Female specimens of Spiculopteragia were present in all five animals. Male specimens of S. spiculoptera and S. asymmetrica were present in one of five and three of five red deer, respectively. Spiculopteragia spiculoptera has not previously been recognized in the United States and the present report constitutes the first records of Spiculopteragia spp. in red deer from North America. It is likely that species of Spiculopteragia have been introduced to North America with the import of exotic cervids on several occasions. Focal populations of these nematodes have been established in North America; however, distribution of the parasites likely coincides with areas of residence of introduced populations of red deer and fallow deer (Cervus dama) in the Nearctic