Dataset Information

Epidemiology of the lymphatic-dwelling filarioid nematode Rumenfilaria andersoni in free-ranging moose (Alces alces) and other cervids of North America.

ABSTRACT: Moose (Alces alces) are a culturally and economically valued species in Minnesota, where the northeast population has decreased by 60 % since 2006. The cause of the decline is currently unclear; however, parasites, predation, and climate change have all been implicated. Nematode parasites are important pathogens in North American moose, potentially causing severe disease and mortality. Recent spread of Rumenfilaria andersoni, a filarioid nematode of moose, has been documented in Finnish cervids; however, little is known about the epidemiology of this parasite in North America.To investigate the prevalence and distribution of R. andersoni, 584 blood samples were collected from live-captured and dead animals and screened microscopically for the presence of microfilariae using a modified Knott's test. Microfilariae were identified based on morphological characteristics. A subset of Knott's-positive animals was subjected to polymerase chain reaction (PCR) with filarioid-specific primers targeting the first internal transcribed spacer region (ITS-1) of the rRNA gene cluster.Rumenfilaria microfilariae were present in 20.5 % of Minnesota moose (n?=?352), with slight fluctuations observed over four years. Minnesota white-tailed deer (Odocoileus virginianus) (n?=?2) and moose (n?=?44) from Alaska, Montana, Washington, Maine, and New Hampshire also harbored R. andersoni, suggesting this parasite occurs widely throughout North American moose herds, and white-tailed deer can serve as a patent host. Sequence analysis of cervid blood (moose, n?=?15; white-tailed deer, n?=?1) confirmed the identity of R. andersoni and revealed the existence of two distinct clades. Genetic comparisons of R. andersoni isolates from North America and semi-domesticated Finnish reindeer found the two groups to be closely related, supporting previous hypotheses that R. andersoni was recently introduced into Finland by the importation of deer from the United States.To the best of our knowledge these observations represent the first report of R. andersoni within the contiguous United States and reveal this nematode as a common parasite of North American moose and white-tailed deer. Although the implications of R. andersoni infection on moose health is unclear, increased awareness of this parasite will help prevent unintentional introduction of R. andersoni into naïve populations via the translocation of wild and captive cervids.

SUBMITTER: Grunenwald CM

PROVIDER: S-EPMC4983095 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Epidemiology of the lymphatic-dwelling filarioid nematode Rumenfilaria andersoni in free-ranging moose (Alces alces) and other cervids of North America.

Grunenwald Caroline M CM Carstensen Michelle M Hildebrand Erik E Elam Jacob J Laaksonen Sauli S Oksanen Antti A Gerhold Richard W RW

Parasites & vectors 20160812 1

<h4>Background</h4>Moose (Alces alces) are a culturally and economically valued species in Minnesota, where the northeast population has decreased by 60 % since 2006. The cause of the decline is currently unclear; however, parasites, predation, and climate change have all been implicated. Nematode parasites are important pathogens in North American moose, potentially causing severe disease and mortality. Recent spread of Rumenfilaria andersoni, a filarioid nematode of moose, has been documented ...[more]

PMID: 27519789

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Project description:In North America, some moose populations are declining, and meningeal worm (Parelaphostrongylus tenuis) infections may be contributing. Moose are aberrant hosts for meningeal worm and develop severe pathology whereas white-tailed deer (WTD) are definitive hosts that experience minimal pathology and spread parasite larvae into the environment. Analyses of harvested WTD heads confirmed meningeal worm in Western Manitoba, Canada including in areas where moose have experienced population declines and are currently of management concern. The prevalence of larval meningeal worm from WTD feces in these areas are unknown, particularly because the dorsal-spined larvae (DSL) are morphologically indistinguishable from muscle worm (Parelaphostrongylus andersoni). To assess transmission risk of DSL, we investigated the spatial and temporal variation of prevalence in WTD feces from four areas (two with historical moose population declines and two without) sampled across two summers. We predicted higher prevalence of DSL in areas where moose are of management concern and surveys have shown higher meningeal worm prevalence in WTD heads. Further, we expected to only recover meningeal worm, as muscle worm has only been reported from caribou in more northern areas of Manitoba. We collected WTD feces by transect sampling, used the Baermann technique to obtain larvae, and sequenced partial cytochrome oxidase 1 and internal transcribed spacer 2 genes to confirm species identity. Zero-inflated models revealed that DSL prevalence did not differ temporally but was higher in areas where moose are of management concern. Genetic analyses revealed that meningeal worm and muscle worm were both present in Western Manitoba and co-occurred in three areas. Our results reveal novel insights into the geographic distribution of muscle worm and emphasize the importance of DNA sequencing for DSL identification. We suggest that concern for moose populations is warranted given the increased risk of parasite infection in some management areas.

Project description:Given recent and abrupt declines in the abundance of moose (Alces alces) throughout parts of Minnesota and elsewhere in North America, accurately estimating statewide population trends and demographic parameters is a high priority for their continued management and conservation. Statistical population reconstruction using integrated population models provides a flexible framework for combining information from multiple studies to produce robust estimates of population abundance, recruitment, and survival. We used this framework to combine aerial survey data and survival data from telemetry studies to recreate trends and demographics of moose in northeastern Minnesota, USA, from 2005 to 2020. Statistical population reconstruction confirmed the sharp decline in abundance from an estimated 7,841 (90% CI = 6,702-8,933) in 2009 to 3,386 (90% CI = 2,681-4,243) animals in 2013, but also indicated that abundance has remained relatively stable since then, except for a slight decline to 3,163 (90% CI = 2,403-3,718) in 2020. Subsequent stochastic projection of the population from 2021 to 2030 suggests that this modest decline will continue for the next 10 years. Both annual adult survival and per-capita recruitment (number of calves that survived to 1 year per adult female alive during the previous year) decreased substantially in years 2005 and 2019, from 0.902 (SE = 0.043) to 0.689 (SE = 0.061) and from 0.386 (SE = 0.030) to 0.303 (SE = 0.051), respectively. Sensitivity analysis revealed that moose abundance was more sensitive to fluctuations in adult survival than recruitment; thus, we conclude that the steep decline in 2013 was driven primarily by decreasing adult survival. Our analysis demonstrates the potential utility of using statistical population reconstruction to monitor moose population trends and to identify population declines more quickly. Future studies should focus on providing better estimates of per-capita recruitment, using pregnancy rates and calf survival, which can then be incorporated into reconstruction models to help improve estimates of population change through time.

Dataset Information

Epidemiology of the lymphatic-dwelling filarioid nematode Rumenfilaria andersoni in free-ranging moose (Alces alces) and other cervids of North America.

Publications

Epidemiology of the lymphatic-dwelling filarioid nematode Rumenfilaria andersoni in free-ranging moose (Alces alces) and other cervids of North America.

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