A New Lungworm in Muskoxen: an Exploration in Arctic Parasitology

Ruminants are vital elements of the Holarctic ecosystem. Little is known, however, of the structure or biology of their parasite fauna, particularly in North America. Global warming, coupied with increasing human activity in the Arctic, requires enhanced intemational interdisciplinary efforts to better understand the many factors, including parasites, that influence the population health of caribou, reindeer, muskoxen and wild sheep. The discovery of an unusual new genus of protostrongylid lung nematode in muskoxen from the central Canadian Arctic is described, and the intricacies of the parasite\u27s relationship with its muskoxen definitive hosts, its gastropod intermediate hosts and the arctic environment are discussed

Caudal Polymorphism and Cephalic Morphology among First-Stage Larvae of \u3ci\u3eParelaphostrongylus odocoilei\u3c/i\u3e (Protostrongylidae: Elaphostrongylinae) in Dall’s Sheep from the Mackenzie Mountains, Canada

We demonstrate polymorphism in the structure of the tail among first-stage larvae of Parelaphostrongylus odocoilei (Protostrongylidae). Two distinct larvae, both with a characteristic dorsal spine, include (1) a morphotype with a kinked conical tail marked by three distinct transverse folds or joints and a symmetrical terminal tail spike and (2) a morphotype with a digitate terminal region lacking folds or joints and with an asymmetrical, subterminal tail spike. These divergent larval forms had been postulated as perhaps representing distinct species of elaphostrongyline nematodes. Application of a multilocus approach using ITS-2 sequences from the nuclear genome and COX-II sequences from the mitochondrial genome confirmed the identity of these larvae as P. odocoilei. Additionally, based on scanning electron microscopy (low-temperature field emission), the cephalic region of these larvae consisted of a cuticular triradiate stoma surrounded by six single circumoral papillae of the inner circle, ten papillae of the outer circle (four paired and two single), and two lateral amphids. Ours is the first demonstration of structural polymorphism among larval conspecifics in the Metastrongyloidea and Strongylida. The basis for this polymorphism remains undetermined, but such phenomena, if discovered to be more widespread, may contribute to continued confusion in discriminating among first-stage larvae for species, genera, and subfamilies within Protostrongylidae

Giardia assemblage A: human genotype in muskoxen in the Canadian Arctic

As part of an ongoing program assessing the biodiversity and impacts of parasites in Arctic ungulates we examined 72 fecal samples from muskoxen on Banks Island, Northwest Territories, Canada for Giardia and Cryptosporidium. Cryptosporidium spp. were not detected, but 21% of the samples were positive for Giardia. Sequencing of four isolates of Giardia demonstrated G. duodenalis, Assemblage A, a zoonotic genotype

Detection of European Strain of \u3ci\u3eEchinococcus multilocularis\u3c/i\u3e in North America

To the Editor: In 2009, an alveolar hydatid cyst, the intermediate stage of the cestode Echinococcus multilocularis, was detected in the liver of a dog from Quesnel, British Columbia (BC), Canada, 600 km west of the nearest known record of this parasite in central North America. Alveolar hydatid cysts normally occur in rodent intermediate hosts. However, humans can serve as aberrant intermediate hosts; cysts generally originate in the liver and, in about one third of cases, metastasize throughout the body. Detection of the larval stage of this pathogen in an unusual host in a new geographic region required application of multiple molecular epidemiologic techniques to determine if this was range expansion of a native strain or introduction of a new strain of veterinary and public health concern. The possible establishment of a European strain in North American wildlife, with spillover into domestic dogs, may have implications for public health and require increased vigilance by medical and veterinary personnel in the newly endemic region. Compared with native North American strains, European strains of E. multilocularis appear to have greater potential to cause alveolar hydatid disease (AHD) in humans. These strains are emerging worldwide (increasing in both prevalence and distribution) as a result of changes in landscape, climate, and wildlife–human interfaces. In Europe, human AHD can be fatal (definite or probable cause of death in 23.5% of 119 recent cases) and has low cure rates (5% of 408 recent cases). As of 2000, in Europe and Asia, the estimated cost per case of AHD was US $100,000–$300,000. Therefore, better understanding of the distribution, genetic diversity, and pathogenicity of strains of E. multilocularis is needed to assess risks and mitigate costs for public and veterinary health, as well as to provide evidence for the regulation and screening of imported domestic animals and translocated wildlife

Emergence of Third-Stage Larvae of \u3ci\u3eUmingmakstrongylus pallikuukensis\u3c/i\u3e from Three Gastropod Intermediate Host Species

We investigated the emergence of third-stage larvae (L3) of Umingmakstrongylus pallikuukensis from the slugs Deroceras laeve, Deroceras reticulatum, and the snail Catinella sp. in the laboratory and from D. laeve on the tundra. Third-stage larvae emerged from 8 of 8 D. laeve and 8 of 8 D. reticulatum housed at 20°C in darkness and from 9 of 10 D. laeve and 5 of 5 Catinella sp. housed at 21°C with 10-12 hours of light/day. Larvae emerged from D. laeve and D. reticulatum over a wide range of infection intensities (2-179 and 20-65, respectively), and the patterns of emergence were independent of intensity. The majority of the L3 emerged from most of the Deroceras spp. by 58 or 60 days postinfection (PI). Lower rates of emergence were observed from Catinella sp. Larvae emerged from D. laeve on the tundra by 10 weeks PI and were recovered from the vegetation in some experimental enclosures the following year. Third-stage larvae survived in tap and distilled water at 0-4°C for 13 months. Emergence of L3 of U. pallikuukensis from the intermediate host may increase the temporal and spatial availability of L3 and enhance their survival and transmission

Experimental Infections of Muskoxen (\u3ci\u3eOvibos moschatus\u3c/i\u3e) and Domestic Sheep with \u3ci\u3eUmingmakstrongylus pallikuukensis\u3c/i\u3e (Nematoda: Protostrongylidae): Parasite Development, Population Structure, and Pathology

Three captive muskoxen (Ovibos moschatus) were successfully infected with third-stage larvae of Umingmakstrongylus pallikuukensis digested or emerged from the slugs Deroceras reticulatum and D. laeve, for the first time completing the life cycle of this parasite under experimental conditions. The course of parasite development and patency was followed for 26 months post infection (p.i.) using fecal examinations and radiography. The prepatent periods in two of the muskoxen were 91 and 95 days and the patent period in one extended for 23 months. Larval production peaked 13–14 months p.i. On postmortem of two of the muskoxen at months 14 and 26 p.i., adult parasites were found only within pulmonary cysts and cysts were randomly distributed between left and right lungs. Cyst dimensions were positively correlated with the number of adult parasites they contained. On postmortem of the third muskox at day 97 p.i., not all adult parasites were within typical cysts; two were found free in interlobular septa. Firststage larvae were recovered from lung cysts of this animal but not from feces. Lung pathology in all three muskoxen appeared localized and associated with the adult nematodes. Infection of two sheep with third-stage larvae of U. pallikuukensis did not result in parasite establishment. French abstract: Nous avons réussi à infecter trois Boeufs-musqués (Ovibos moschatus) en captivité au moyen de larves de troisième stade d’Umingmakstrongylus pallikuukensis digérées ou émergées de limaces Deroceras reticulatum et D. laeve, et c’est la première fois que tout le cycle de ce parasite se déroule avec succès dans des conditions expérimentales. Le développement du parasite et l’apparition des symptômes de l’infection ont été observés pendant 26 mois après le début de l’infection par examen des fèces et par radiographie. La période précédant l’apparition des symptômes a été évaluée à 91 et 95 jours chez deux boeufs-musqués et la période symptomatique a duré 23 mois chez l’un d’eux. La production de larves a atteint son maximum 13–14 mois après l’infection. L’examen postmortem de deux des animaux aux mois 14 et 26 de l’infection a révélé la présence de parasites adultes, mais seulement dans des kystes pulmonaires répartis au hasard dans les deux poumons. La taille de ces kystes était directement reliée au nombre de parasites adultes qu’ils contenaient. L’examen postmortem du troisième animal, au jour 97 de l’infection, a révélé que les parasites adultes n’étaient pas tous dans des kystes typiquees, puisque deux d’entre eux ont été trouvés libres dans les septums interlobulaires. Des larves de premier stade ont été repérées dans des kystes pulmonaires, mais pas dans les fèces. La pathologie de ces trois boeufs-musqués semblait bien localisée et associée à la présence des nématodes adultes. Les tentatives d’infection de trois ovidés au moyen de larves de troisième stade d’U. pallikuukensis ont échoué

\u3ci\u3eUmingmakstrongylus pallikuukensis\u3c/i\u3e (Nematoda: Protostrongylidae) in Gastropods: Larval Morphology, Morphometrics, and Development Rates

Morphological and morphometric aspects of larval development of Umingmakstrongylus pallikuukensis in Deroceras laeve and the effects of temperature on development rates in D. laeve and Deroceras reticulatum were investigated in the laboratory. Larval stages were best differentiated by separation of cuticular sheaths, tail structure, and viability following digestion. Growth in body and esophagus width was observed during the first-stage within the intermediate host, but the major increases in body length and width occurred immediately following the second molt. Larval development in D. laeve and D. reticulatum occurred more rapidly at warmer temperatures. The calculated threshold temperatures were 8.5 and 9.5 °C in D. laeve and D. reticulatum, respectively, and 167 degree-days were required for development to third-stage larvae (L3) in both hosts. These thresholds are higher than those calculated from published data for the closely related Muellerius capillaris (4.2 °C) but are similar to those for the more distantly related northern protostrongylid, Elaphostrongylus rangiferi (8.3–10.3 °C). Conversely, degreedays required for development to infective L3 were more similar among the Muelleriinae than between this group and the Elaphostrongylinae. Developmental parameters for protostrongylid larvae may be influenced both by the environment and by features of the parasites and the intermediate hosts, including phylogeny

Development of the Muskox Lungworm, \u3ci\u3eUmingmakstrongylus pallikuukensis\u3c/i\u3e (Protostrongylidae), in Gastropods in the Arctic

Development of the muskox protostrongylid lungworm, Umingmakstrongylus pallikuukensis, in its slug intermediate host, Deroceras laeve, was investigated under field conditions in the Arctic. Every two weeks, from 19 June to 28 August 1997, groups of ten experimentally infected slugs were placed in tundra enclosures in a mesic sedge meadow near Kugluktuk, Nunavut, Canada. First-stage larvae (L1) infecting slugs on or before 17 July developed to third-stage larvae (L3) in 4–6 weeks. Intensity of L3 in slugs peaked at 6–8 weeks post infection (PI) and then progressively declined by 10, 12, and 48–50 weeks PI. Abundance of L3 in slugs was greatest during mid to late August. L1 infecting slugs on 31 July or later did not develop to L3 before the end of September but overwintered in slugs on the tundra as L1 or as second-stage larvae, completing development to L3 the following summer. The years 1997 and 1998 were exceptionally warm and, in cooler years, rates of larval development may be slower and patterns of availability may differ. The amount of heating (degree-days) accumulated during each trial was calculated using the 8.5C threshold determined in the laboratory, a 21C maximum, and either surface, soil, or air temperature. Only degree-days accumulated at the surface were sufficient to correspond to the observed rates of larval development. This enclosure-based system and associated degree-day calculations may be used for predicting the effects of climate and climate change on patterns of parasite development and transmission in the Arctic. French abstract: Nous avons étudié le développement du ver du poumon du boeuf-musqué, Umingmakstrongylus pallikuukensis, chez son hôte intermédiaire, la limace Deroceras laeve, en nature dans l’Arctique. Toutes les deux semaines, du 19 juin au 28 août 1997, nous avons mis dix limaces infectées expérimentalement dans des enceintes de la toundra, dans une prairie à laîches mésique, près de Kugluktuk, Nunavut, Canada. Les larves de premier stade (L1) qui ont infecté les limaces jusqu’au 17 juillet inclusivement sont parvenues au troisième stade larvaire (L3) en 4–6 semaines. L’intensité des infections des limaces par les larves L3 a atteint un sommet 6–8 semaines après l’infection (PI) pour décliner par la suite, tel qu’observé aux semaines 10, 12 et 48–50 PI. L’abondance des larves L3 chez les limaces a été maximale de la mi-août à la fin d’août. Les larves de premier stade qui ont infecté les limaces après le 30 juillet n’ont pas atteint le troisième stade à la fin de septembre, mais elles ont passé l’hiver dans les limaces de la toundra sous forme de larves de premier ou de deuxième stade et ne sont parvenues au stade L3 que l’été suivant. Les années 1997 et 1998 ont été exceptionnellement chaudes et il se peut qu’au cours d’années plus fraîches, le développement soit plus lent et les patterns de disponibilité, différents. La quantité de chaleur accumulée (degrés-jours) à chaque expérience a été calculée en tenant compte du seuil de 8,5C déterminé en laboratoire, de la température maximale de 21C, et de la température de la surface, du sol ou de l’air. Seul le nombre de degrés-jours en surface est suffisamment élevé pour expliquer les taux observés de développement larvaire. Le système à enceintes et le calcul des degrés-jours peuvent servir à prédire les effets du climat et des changements climatiques sur les patterns de développement des parasites et sur leur transmission dans l’Arctique