Publications by authors named "Kathryn P Huyvaert"

32 Publications

Evidence of Arctic Fox Survival following Exposure to Rabies Virus.

J Wildl Dis 2021 Nov 23. Epub 2021 Nov 23.

US Department of Agriculture, National Wildlife Research Center, 4101 Laporte Avenue, Fort Collins, Colorado 80521, USA.

The arctic fox variant of the rabies virus (RABV) is enzootic in the circumpolar north. Reports of abortive RABV exposures motivated a retrospective analysis of sera from 41 arctic foxes captured at Karrak Lake in Nunavut, Canada, during 2011-2015. Estimated RABV antibody prevalence among foxes was 14% (95% confidence interval, 7-28%).
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http://dx.doi.org/10.7589/JWD-D-21-00071DOI Listing
November 2021

Sex and nest type influence avian blood parasite prevalence in a high-elevation bird community.

Parasit Vectors 2021 Mar 8;14(1):145. Epub 2021 Mar 8.

Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA.

Background: The prevalence of avian haemosporidian parasites and the factors influencing infection in the Colorado Rocky Mountains are largely unknown. With climate change expected to promote the expansion of vector and avian blood parasite distributions, baseline knowledge and continued monitoring of the prevalence and diversity of these parasites is needed.

Methods: Using an occupancy modeling framework, we conducted a survey of haemosporidian parasite species infecting an avian community in the Colorado Rocky Mountains in order to estimate the prevalence and diversity of blood parasites and to investigate species-level and individual-level characteristics that may influence infection.

Results: We estimated the prevalence and diversity of avian Haemosporidia across 24 bird species, detecting 39 parasite haplotypes. We found that open-cup nesters have higher Haemoproteus prevalence than cavity or ground nesters. Additionally, we found that male Ruby-crowned Kinglets, White-crowned Sparrows, and Wilson's Warblers have higher Haemoproteus prevalence compared to other host species. Plasmodium prevalence was relatively low (5%), consistent with the idea that competent vectors may be rare at high altitudes.

Conclusions: Our study presents baseline knowledge of haemosporidian parasite presence, prevalence, and diversity among avian species in the Colorado Rocky Mountains and adds to our knowledge of host-parasite relationships of blood parasites and their avian hosts.
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http://dx.doi.org/10.1186/s13071-021-04612-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7938522PMC
March 2021

Teaching Wildlife Disease Outbreak Response Through a Collaborative One Health Workshop.

J Vet Med Educ 2020 Jul 15;47(4):402-407. Epub 2019 Nov 15.

Colorado State University.

Issues in the fields of wildlife disease and One Health are often difficult to address by single research groups because of the many disciplines and areas of expertise required to effectively solve complex problems. Although collaborations are becoming increasingly prevalent in the professional realm, many undergraduate, graduate, and professional students are merely introduced to the idea of collaboration without fully understanding how team-based approaches function. In this report, we describe the framework for a one-day workshop hosted by the Colorado State University student chapter of the Wildlife Disease Association (CSU WDA), where we gathered students and professionals to collectively investigate a simulated wildlife disease outbreak. CSU WDA student members designed the workshop and recruited professionals who are experts in their respective fields to run an outbreak simulation during the event. Based on pre- and post-event evaluation responses, this workshop was effective in increasing participants' knowledge of disease ecology, pathology, genetics, and microbiology, as well as the importance of collaboration among disciplines as it pertains to wildlife disease outbreaks.
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http://dx.doi.org/10.3138/jvme.2018-0020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7316304PMC
July 2020

Challenges and Opportunities Developing Mathematical Models of Shared Pathogens of Domestic and Wild Animals.

Vet Sci 2018 Oct 30;5(4). Epub 2018 Oct 30.

U.S. Geological Survey, National Wildlife Health Center, Madison, WI 53711, USA.

Diseases that affect both wild and domestic animals can be particularly difficult to prevent, predict, mitigate, and control. Such multi-host diseases can have devastating economic impacts on domestic animal producers and can present significant challenges to wildlife populations, particularly for populations of conservation concern. Few mathematical models exist that capture the complexities of these multi-host pathogens, yet the development of such models would allow us to estimate and compare the potential effectiveness of management actions for mitigating or suppressing disease in wildlife and/or livestock host populations. We conducted a workshop in March 2014 to identify the challenges associated with developing models of pathogen transmission across the wildlife-livestock interface. The development of mathematical models of pathogen transmission at this interface is hampered by the difficulties associated with describing the host-pathogen systems, including: (1) the identity of wildlife hosts, their distributions, and movement patterns; (2) the pathogen transmission pathways between wildlife and domestic animals; (3) the effects of the disease and concomitant mitigation efforts on wild and domestic animal populations; and (4) barriers to communication between sectors. To promote the development of mathematical models of transmission at this interface, we recommend further integration of modern quantitative techniques and improvement of communication among wildlife biologists, mathematical modelers, veterinary medicine professionals, producers, and other stakeholders concerned with the consequences of pathogen transmission at this important, yet poorly understood, interface.
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http://dx.doi.org/10.3390/vetsci5040092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6313884PMC
October 2018

Beyond the swab: ecosystem sampling to understand the persistence of an amphibian pathogen.

Oecologia 2018 Sep 2;188(1):319-330. Epub 2018 Jun 2.

Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA.

Understanding the ecosystem-level persistence of pathogens is essential for predicting and measuring host-pathogen dynamics. However, this process is often masked, in part due to a reliance on host-based pathogen detection methods. The amphibian pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are pathogens of global conservation concern. Despite having free-living life stages, little is known about the distribution and persistence of these pathogens outside of their amphibian hosts. We combine historic amphibian monitoring data with contemporary host- and environment-based pathogen detection data to obtain estimates of Bd occurrence independent of amphibian host distributions. We also evaluate differences in filter- and swab-based detection probability and assess inferential differences arising from using different decision criteria used to classify samples as positive or negative. Water filtration-based detection probabilities were lower than those from swabs but were > 10%, and swab-based detection probabilities varied seasonally, declining in the early fall. The decision criterion used to classify samples as positive or negative was important; using a more liberal criterion yielded higher estimates of Bd occurrence than when a conservative criterion was used. Different covariates were important when using the liberal or conservative criterion in modeling Bd detection. We found evidence of long-term Bd persistence for several years after an amphibian host species of conservation concern, the boreal toad (Anaxyrus boreas boreas), was last detected. Our work provides evidence of long-term Bd persistence in the ecosystem, and underscores the importance of environmental samples for understanding and mitigating disease-related threats to amphibian biodiversity.
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http://dx.doi.org/10.1007/s00442-018-4167-6DOI Listing
September 2018

Host-pathogen metapopulation dynamics suggest high elevation refugia for boreal toads.

Ecol Appl 2018 06 7;28(4):926-937. Epub 2018 May 7.

Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, 80523, USA.

Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situ disease management. Declines of boreal toads (Anaxyrus boreas boreas) in the southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic data set, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be suboptimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bd systems. Our data suggest that in the southern Rocky Mountains high elevation sites should be prioritized for conservation initiatives like reintroductions.
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http://dx.doi.org/10.1002/eap.1699DOI Listing
June 2018

Detection and persistence of environmental DNA from an invasive, terrestrial mammal.

Ecol Evol 2018 01 3;8(1):688-695. Epub 2017 Dec 3.

Wildlife Genetics Lab USDA, Wildlife Services, National Wildlife Research Center Fort Collins CO USA.

Invasive , a species commonly referred to as wild pig or feral swine, is a destructive invasive species with a rapidly expanding distribution across the United States. We used artificial wallows and small waterers to determine the minimum amount of time needed for pig eDNA to accumulate in the water source to a detectable level. We removed water from the artificial wallows and tested eDNA detection over the course of 2 weeks to understand eDNA persistence. We show that our method is sensitive enough to detect very low quantities of eDNA shed by a terrestrial mammal that has limited interaction with water. Our experiments suggest that the number of individuals shedding into a water system can affect persistence of eDNA. Use of an eDNA detection technique can benefit management efforts by providing a sensitive method for finding even small numbers of individuals that may be elusive using other methods.
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http://dx.doi.org/10.1002/ece3.3698DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5756866PMC
January 2018

Design- and model-based recommendations for detecting and quantifying an amphibian pathogen in environmental samples.

Ecol Evol 2017 12 12;7(24):10952-10962. Epub 2017 Nov 12.

Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA.

Accurate pathogen detection is essential for developing management strategies to address emerging infectious diseases, an increasingly prominent threat to wildlife. Sampling for free-living pathogens outside of their hosts has benefits for inference and study efficiency, but is still uncommon. We used a laboratory experiment to evaluate the influences of pathogen concentration, water type, and qPCR inhibitors on the detection and quantification of () using water filtration. We compared results pre- and post-inhibitor removal, and assessed inferential differences when single versus multiple samples were collected across space or time. We found that qPCR inhibition influenced both detection and quantification in natural water samples, resulting in biased inferences about occurrence and abundance. Biases in occurrence could be mitigated by collecting multiple samples in space or time, but biases in quantification were persistent. Differences in concentration resulted in variation in detection probability, indicating that occupancy modeling could be used to explore factors influencing heterogeneity in abundance among samples, sites, or over time. Our work will influence the design of studies involving amphibian disease dynamics and studies utilizing environmental DNA (eDNA) to understand species distributions.
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http://dx.doi.org/10.1002/ece3.3616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743658PMC
December 2017

Avian Pox Discovered in the Critically Endangered Waved Albatross (Phoebastria irrorata) from the Galápagos Islands, Ecuador.

J Wildl Dis 2017 10 17;53(4):891-895. Epub 2017 Jul 17.

3 Department of Fish, Wildlife, and Conservation Biology, 1474 Campus Delivery, Colorado State University, Fort Collins, Colorado 80523, USA.

The Waved Albatross (Phoebastria irrorata) is a critically endangered seabird in a rapidly shrinking population in the Galápagos Islands, Ecuador. The introduction of novel pathogens and parasites poses a threat to population persistence. Monitoring disease prevalence and guarding against the spread of such agents in endemic taxa are conservation priorities for the Galápagos, where recent increases in the prevalence of avian pox may have contributed to population declines and range contractions in other bird species. During November 2013-January 2014, we identified 14 Waved Albatross nestlings at our study site on Española Island with avian pox-like lesions and clinical signs. Other seabirds, landbirds, and adult Waved Albatrosses were apparently unaffected. Histopathology of tissue samples from five infected nestlings revealed inclusion bodies in all samples, consistent with avipoxvirus infection. We documented higher mortality (6 of 14 nestlings) in affected nestlings than in unaffected young in this small outbreak of avian pox, the first report of its kind in the world's only tropical albatross.
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http://dx.doi.org/10.7589/2016-12-264DOI Listing
October 2017

Clearing muddied waters: Capture of environmental DNA from turbid waters.

PLoS One 2017 7;12(7):e0179282. Epub 2017 Jul 7.

USDA, Wildlife Services, National Wildlife Research Center, Wildlife Genetics Lab, Fort Collins, Colorado, United States of America.

Understanding the differences in efficiencies of various methods to concentrate, extract, and amplify environmental DNA (eDNA) is vital for best performance of eDNA detection. Aquatic systems vary in characteristics such as turbidity, eDNA concentration, and inhibitor load, thus affecting eDNA capture efficiency. Application of eDNA techniques to the detection of terrestrial invasive or endangered species may require sampling at intermittent water sources that are used for drinking and cooling; these water bodies may often be stagnant and turbid. We present our best practices technique for the detection of wild pig eDNA in water samples, a protocol that will have wide applicability to the detection of elusive vertebrate species. We determined the best practice for eDNA capture in a turbid water system was to concentrate DNA from a 15 mL water sample via centrifugation, purify DNA with the DNeasy mericon Food kit, and remove inhibitors with Zymo Inhibitor Removal Technology columns. Further, we compared the sensitivity of conventional PCR to quantitative PCR and found that quantitative PCR was more sensitive in detecting lower concentrations of eDNA. We show significant differences in efficiencies among methods in each step of eDNA capture, emphasizing the importance of optimizing best practices for the system of interest.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0179282PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5501390PMC
October 2017

Picky eaters are rare: DNA-based blood meal analysis of Culicoides (Diptera: Ceratopogonidae) species from the United States.

Parasit Vectors 2017 Apr 4;10(1):169. Epub 2017 Apr 4.

USDA-APHIS-National Wildlife Research Center, 4101 Laporte Ave., Fort Collins, CO, 80521, USA.

Background: Biting midges in the genus Culicoides (Diptera; Ceratopogonidae) have been implicated in the transmission of a number of parasites and highly pathogenic viruses. In North America, the complete transmission cycles of many of these pathogens need further elucidation. One way to increase our knowledge about the evolution and ecology of Culicoides species and the pathogens they transmit is to document the diversity of vertebrate hosts that Culicoides feed upon. Our objective was to identify the diversity of Culicoides hosts in the United States.

Results: We sequenced two vertebrate mitochondrial genes (cytochrome c oxidase subunit 1 and cytochrome b) from blood-engorged Culicoides to identify Culicoides species and their blood meals. We detected the mitochondrial DNA of 12 host species from seven different Culicoides species from three states. The majority of the identified blood meals were from the C. variipennis species complex in California. The hosts included both mammals and birds. We documented new host records for some of the Culicoides species collected. The majority of the mammalian hosts were large ungulate species but we also detected a lagomorph and a carnivore. The bird species that were detected included house finch and emu; the latter is evidence that the species in the C. variipennis species complex are not strictly mammalophilic.

Conclusions: These results demonstrate that Culicoides will feed on multiple classes of vertebrates and may be more opportunistic in regards to host choice than previously thought. This knowledge can help with identification of susceptible host species, pathogen reservoirs, and new vector species which, in turn, will improve disease outbreak risk assessments.
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http://dx.doi.org/10.1186/s13071-017-2099-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5381053PMC
April 2017

Management and modeling approaches for controlling raccoon rabies: The road to elimination.

PLoS Negl Trop Dis 2017 03 16;11(3):e0005249. Epub 2017 Mar 16.

United States Department of Agriculture, National Wildlife Research Center, Fort Collins, Colorado, United States of America.

Rabies is an ancient viral disease that significantly impacts human and animal health throughout the world. In the developing parts of the world, dog bites represent the highest risk of rabies infection to people, livestock, and other animals. However, in North America, where several rabies virus variants currently circulate in wildlife, human contact with the raccoon rabies variant leads to the highest per capita population administration of post-exposure prophylaxis (PEP) annually. Previous rabies variant elimination in raccoons (Canada), foxes (Europe), and dogs and coyotes (United States) demonstrates that elimination of the raccoon variant from the eastern US is feasible, given an understanding of rabies control costs and benefits and the availability of proper tools. Also critical is a cooperatively produced strategic plan that emphasizes collaborative rabies management among agencies and organizations at the landscape scale. Common management strategies, alone or as part of an integrated approach, include the following: oral rabies vaccination (ORV), trap-vaccinate-release (TVR), and local population reduction. As a complement, mathematical and statistical modeling approaches can guide intervention planning, such as through contact networks, circuit theory, individual-based modeling, and others, which can be used to better understand and predict rabies dynamics through simulated interactions among the host, virus, environment, and control strategy. Strategies derived from this ecological lens can then be optimized to produce a management plan that balances the ecological needs and program financial resources. This paper discusses the management and modeling strategies that are currently used, or have been used in the past, and provides a platform of options for consideration while developing raccoon rabies virus elimination strategies in the US.
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http://dx.doi.org/10.1371/journal.pntd.0005249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5354248PMC
March 2017

No filters, no fridges: a method for preservation of water samples for eDNA analysis.

BMC Res Notes 2016 Jun 8;9:298. Epub 2016 Jun 8.

Wildlife Services, National Wildlife Research Center, Wildlife Genetics Lab, USDA, 4101 LaPorte Avenue, Fort Collins, CO, 80521, USA.

Background: Advancements in the detection of environmental DNA (eDNA) for detecting species of interest will likely allow for expanded use of these techniques in the field. One obstacle that continues to hinder applications in the field is the requirement of a cold chain of storage for water samples containing eDNA. While eDNA has been successfully preserved using Longmire's lysis buffer applied to filters, it has yet to be tried with freshwater samples collected for eDNA detection of an invasive species. We tested the utility of Longmire's solution (100 mM Tris, 100 mM EDTA, 10 mM NaCl, 0.5 % SDS, 0.2 % sodium azide) as an additive to freshwater samples for preservation of eDNA.

Results: Environmental DNA was effectively preserved in 15 mL water samples with Longmire's solution added; eDNA positive detection was comparable to freezing the samples at -80 °C and occurred out to 56 days at the highest concentration (5 mL Longmire's solution: 15 mL sample water). Medium and low concentrations of Longmire's solution added to 15 mL of sample water generally preserved eDNA out to 56 days but not as well as did freezing or application of the highest concentration of Longmire's lysis buffer. Treatment and degradation time had a significant effect on average DNA concentration of samples, although not the interaction of treatment and time. Perfect detection occurred out to 56 days with the high Longmire's treatment group but DNA concentration was significantly lower at this time point compared to 28 days.

Conclusion: We conclude that Longmire's lysis buffer is a viable alternative to cold chain storage that can simplify the collection of eDNA by eliminating the need for filtering and allow more time for sample collection when added at our highest concentration (1 part Longmire's:3 parts water sample), which could translate to an increase in the chances of detecting a rare or elusive species.
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http://dx.doi.org/10.1186/s13104-016-2104-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4898389PMC
June 2016

Multi-scale occupancy approach to estimate Toxoplasma gondii prevalence and detection probability in tissues: an application and guide for field sampling.

Int J Parasitol 2016 08 4;46(9):563-70. Epub 2016 May 4.

Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.

Increasingly, birds are recognised as important hosts for the ubiquitous parasite Toxoplasma gondii, although little experimental evidence exists to determine which tissues should be tested to maximise the detection probability of T. gondii. Also, Arctic-nesting geese are suspected to be important sources of T. gondii in terrestrial Arctic ecosystems, but the parasite has not previously been reported in the tissues of these geese. Using a domestic goose model, we applied a multi-scale occupancy framework to demonstrate that the probability of detection of T. gondii was highest in the brain (0.689, 95% confidence interval=0.486, 0.839) and the heart (0.809, 95% confidence interval=0.693, 0.888). Inoculated geese had an estimated T. gondii infection probability of 0.849, (95% confidence interval=0.643, 0.946), highlighting uncertainty in the system, even under experimental conditions. Guided by these results, we tested the brains and hearts of wild Ross's Geese (Chen rossii, n=50) and Lesser Snow Geese (Chen caerulescens, n=50) from Karrak Lake, Nunavut, Canada. We detected 51 suspected positive tissue samples from 33 wild geese using real-time PCR with melt-curve analysis. The wild goose prevalence estimates generated by our multi-scale occupancy analysis were higher than the naïve estimates of prevalence, indicating that multiple PCR repetitions on the same organs and testing more than one organ could improve T. gondii detection. Genetic characterisation revealed Type III T. gondii alleles in six wild geese and Sarcocystis spp. in 25 samples. Our study demonstrates that Arctic nesting geese are capable of harbouring T. gondii in their tissues and could transport the parasite from their southern overwintering grounds into the Arctic region. We demonstrate how a multi-scale occupancy framework can be used in a domestic animal model to guide resource-limited sample collection and tissue analysis in wildlife. Secondly, we confirm the value of traditional occupancy in optimising T. gondii detection probability in tissue samples.
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http://dx.doi.org/10.1016/j.ijpara.2016.04.003DOI Listing
August 2016

"One Health" or Three? Publication Silos Among the One Health Disciplines.

PLoS Biol 2016 Apr 21;14(4):e1002448. Epub 2016 Apr 21.

U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana, United States of America.

The One Health initiative is a global effort fostering interdisciplinary collaborations to address challenges in human, animal, and environmental health. While One Health has received considerable press, its benefits remain unclear because its effects have not been quantitatively described. We systematically surveyed the published literature and used social network analysis to measure interdisciplinarity in One Health studies constructing dynamic pathogen transmission models. The number of publications fulfilling our search criteria increased by 14.6% per year, which is faster than growth rates for life sciences as a whole and for most biology subdisciplines. Surveyed publications clustered into three communities: one used by ecologists, one used by veterinarians, and a third diverse-authorship community used by population biologists, mathematicians, epidemiologists, and experts in human health. Overlap between these communities increased through time in terms of author number, diversity of co-author affiliations, and diversity of citations. However, communities continue to differ in the systems studied, questions asked, and methods employed. While the infectious disease research community has made significant progress toward integrating its participating disciplines, some segregation--especially along the veterinary/ecological research interface--remains.
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http://dx.doi.org/10.1371/journal.pbio.1002448DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4839662PMC
April 2016

ESTIMATING TOXOPLASMA GONDII EXPOSURE IN ARCTIC FOXES (VULPES LAGOPUS) WHILE NAVIGATING THE IMPERFECT WORLD OF WILDLIFE SEROLOGY.

J Wildl Dis 2016 Jan;52(1):47-56

1  University of Saskatchewan, Department of Veterinary Microbiology, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.

Although the protozoan parasite Toxoplasma gondii is ubiquitous in birds and mammals worldwide, the full suite of hosts and transmission routes is not completely understood, especially in the Arctic. Toxoplasma gondii occurrence in humans and wildlife can be high in Arctic regions, despite apparently limited opportunities for transmission of oocysts shed by felid definitive hosts. Arctic foxes (Vulpes lagopus) are under increasing anthropogenic and ecologic pressure, leading to population declines in parts of their range. Our understanding of T. gondii occurrence in arctic foxes is limited to only a few regions, but mortality events caused by this parasite have been reported. We investigated the exposure of arctic foxes to T. gondii in the Karrak Lake goose colony, Queen Maud Gulf Migratory Bird Sanctuary, Nunavut, Canada. Following an occupancy-modeling framework, we performed replicated antibody testing on serum samples by direct agglutination test (DAT), indirect fluorescent antibody test (IFAT), and an indirect enzyme-linked immunosorbent assay (ELISA) that can be used in multiple mammalian host species. As a metric of test performance, we then estimated the probability of detecting T. gondii antibodies for each of the tests. Occupancy estimates for T. gondii antibodies in arctic foxes under this framework were between 0.430 and 0.758. Detection probability was highest for IFAT (0.716) and lower for DAT (0.611) and ELISA (0.464), indicating that the test of choice for antibody detection in arctic foxes might be the IFAT. We document a new geographic record of T. gondii exposure in arctic foxes and demonstrate an emerging application of ecologic modeling techniques to account for imperfect performance of diagnostic tests in wildlife species.
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http://dx.doi.org/10.7589/2015-03-075DOI Listing
January 2016

Gastrointestinal Parasites in the Waved Albatross (Phoebastria irrorata) of Galápagos.

J Wildl Dis 2015 Jul 28;51(3):784-6. Epub 2015 Apr 28.

5  Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado 80523, USA.

Using a fecal flotation technique, we detected three genera of endoparasites in the critically endangered Waved Albatross (Phoebastria irrorata) of Galápagos. These genera were Contracaecum, Tetrabothrius, and Cardiocephaloides. Juvenile albatrosses were more likely to be infected than adults, but we found no effect of sex or mass on infection probability.
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http://dx.doi.org/10.7589/2014-06-165DOI Listing
July 2015

Prevalence of the generalist flea Pulex simulans on black-tailed prairie dogs (Cynomys ludovicianus) in New Mexico, USA: the importance of considering imperfect detection.

J Wildl Dis 2015 Apr 14;51(2):498-502. Epub 2015 Jan 14.

1  Graduate Degree Program in Ecology, Colorado State University, 1878 Campus Delivery, Fort Collins, Colorado 80523-1878, USA.

If a parasite is not detected during a survey, one of two explanations is possible: the parasite was truly absent or it was present but not detected. We fit occupancy models to account for imperfect detection when combing fleas (Siphonaptera) from black-tailed prairie dogs (Cynomys ludovicianus) during June-August 2012 in the Vermejo Park Ranch, New Mexico, USA. With the use of detection histories from combing events during monthly trapping sessions, we fit occupancy models for two flea species: Oropsylla hirusta (a prairie dog specialist) and Pulex simulans (a generalist). Detection probability was <100% for both species and about 21% lower for P. simulans. Pulex simulans may be especially difficult to detect because it is about half the size of O. hirusta. Monthly occupancy (prevalence) for P. simulans was estimated at 24% (June, 95% confidence interval = 19-30), 39% (July, 32-47), and 56% (August, 49-64) in new prairie dog colonies, and 43% (32-54), 61% (49-71), and 79% (70-87) in old colonies. These results suggest P. simulans can attain high prevalence on prairie dogs, especially in old colonies. If P. simulans is highly prevalent on prairie dogs, it may serve as a "bridge vector" between Cynomys and other mammalian hosts of the plague bacterium Yersinia pestis, and even function as a reservoir of Y. pestis between outbreaks.
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http://dx.doi.org/10.7589/2014-07-178DOI Listing
April 2015

Bighorn sheep (Ovis canadensis) sinus tumors are associated with coinfections by potentially pathogenic bacteria in the upper respiratory tract.

J Wildl Dis 2015 Jan;51(1):19-27

1 Colorado Parks and Wildlife, Wildlife Health Program, 4330 W Laporte Avenue, Fort Collins, Colorado 80521, USA.

Bighorn sheep (Ovis canadensis) sinus tumors are hyperplastic to neoplastic, predominantly stromal masses of the paranasal sinuses that expand the sinus lining and obstruct the sinus cavities. Obstruction of the sinus cavities and disruption of normal sinus lining anatomy may interfere with clearance of bacterial pathogens from the upper respiratory tract. To examine this possibility, we explored whether the presence of sinus tumor features (tumor score) affected the likelihood of detecting potentially pathogenic bacteria from upper respiratory sinus lining tissues in bighorn sheep. We developed or used existing PCR assays for the detection of leukotoxigenic Pasteurellaceae and Mycoplasma ovipneumoniae in sinus lining tissues collected from 97 bighorn sheep in Colorado, US from 2009 to 2012. With the use of logistic regression analyses we found that tumor score was a good predictor of the probability of detecting potentially pathogenic bacteria in sinus lining tissues; we were more likely to detect potentially pathogenic bacteria from samples with high tumor scores. These findings add to our understanding of possible mechanisms for the maintenance and shedding of bacterial agents from the upper respiratory tracts of bighorn sheep.
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http://dx.doi.org/10.7589/2014-05-130DOI Listing
January 2015

Toxoplasma gondii exposure in arctic-nesting geese: A multi-state occupancy framework and comparison of serological assays.

Int J Parasitol Parasites Wildl 2014 Aug 30;3(2):147-53. Epub 2014 Jun 30.

Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N5B4, Canada.

The zoonotic parasite, Toxoplasma gondii, has a worldwide distribution and a cosmopolitan suite of hosts. In arctic tundra regions, the definitive felid hosts are rare to absent and, while the complete transmission routes in such regions have yet to be fully elucidated, trophic and vertical routes are likely to be important. Wild birds are common intermediate hosts of T. gondii, and in the central Canadian arctic, geese are probable vectors of the parasite from temperate latitudes to the arctic regions. Our objective was to estimate seroprevalence of T. gondii in Ross's and Lesser Snow Geese from the Karrak Lake ecosystem in Nunavut, Canada. After harvesting geese by shotgun, we collected blood on filter paper strips and tested the eluate for T. gondii antibodies by indirect fluorescent antibody test (IFAT) and direct agglutination test (DAT). We estimated seroprevalence using a multi-state occupancy model, which reduced bias by accounting for imperfect detection, and compared these estimates to a naïve estimator. Ross's Geese had a 0.39 probability of seropositivity, while for Lesser Snow Geese the probability of positive for T. gondii antibodies was 0.36. IFAT had a higher antibody detection probability than DAT, but IFAT also had a higher probability of yielding ambiguous or unclassifiable results. The results of this study indicate that Ross's Geese and Lesser Snow Geese migrating to the Karrak Lake region of Nunavut are routinely exposed to T. gondii at some point in their lives and that they are likely intermediate hosts of the parasite. Also, we were able to enhance our estimation of T. gondii seroprevalence by using an occupancy approach that accounted for both false-negative and false-positive detections and by using multiple diagnostic tests in the absence of a gold standard serological assay for wild geese.
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http://dx.doi.org/10.1016/j.ijppaw.2014.05.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4142267PMC
August 2014

Using occupancy models to investigate the prevalence of ectoparasitic vectors on hosts: An example with fleas on prairie dogs.

Int J Parasitol Parasites Wildl 2013 Dec 19;2:246-56. Epub 2013 Sep 19.

Graduate Degree Program in Ecology, Colorado State University, CO 80523, USA ; Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.

Ectoparasites are often difficult to detect in the field. We developed a method that can be used with occupancy models to estimate the prevalence of ectoparasites on hosts, and to investigate factors that influence rates of ectoparasite occupancy while accounting for imperfect detection. We describe the approach using a study of fleas (Siphonaptera) on black-tailed prairie dogs (Cynomys ludovicianus). During each primary occasion (monthly trapping events), we combed a prairie dog three consecutive times to detect fleas (15 s/combing). We used robust design occupancy modeling to evaluate hypotheses for factors that might correlate with the occurrence of fleas on prairie dogs, and factors that might influence the rate at which prairie dogs are colonized by fleas. Our combing method was highly effective; dislodged fleas fell into a tub of water and could not escape, and there was an estimated 99.3% probability of detecting a flea on an occupied host when using three combings. While overall detection was high, the probability of detection was always <1.00 during each primary combing occasion, highlighting the importance of considering imperfect detection. The combing method (removal of fleas) caused a decline in detection during primary occasions, and we accounted for that decline to avoid inflated estimates of occupancy. Regarding prairie dogs, flea occupancy was heightened in old/natural colonies of prairie dogs, and on hosts that were in poor condition. Occupancy was initially low in plots with high densities of prairie dogs, but, as the study progressed, the rate of flea colonization increased in plots with high densities of prairie dogs in particular. Our methodology can be used to improve studies of ectoparasites, especially when the probability of detection is low. Moreover, the method can be modified to investigate the co-occurrence of ectoparasite species, and community level factors such as species richness and interspecific interactions.
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http://dx.doi.org/10.1016/j.ijppaw.2013.09.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3862499PMC
December 2013

Failure of transmission of low-pathogenic avian influenza virus between Mallards and freshwater snails: an experimental evaluation.

J Wildl Dis 2013 Oct;49(4):911-9

1  US Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado 80521, USA.

In aquatic bird populations, the ability of avian influenza (AI) viruses to remain infectious in water for extended periods provides a mechanism that allows viral transmission to occur long after shedding birds have left the area. However, this also exposes other aquatic organisms, including freshwater invertebrates, to AI viruses. Previous researchers found that AI viral RNA can be sequestered in snail tissues. Using an experimental approach, we determined whether freshwater snails (Physa acuta and Physa gyrina) can infect waterfowl with AI viruses by serving as a means of transmission between infected and naïve waterfowl via ingestion. In our first experiment, we exposed 20 Physa spp. snails to an AI virus (H3N8) and inoculated embryonated specific pathogen-free (SPF) chicken eggs with the homogenized snail tissues. Sequestered AI viruses remain infectious in snail tissues; 10% of the exposed snail tissues infected SPF eggs. In a second experiment, we exposed snails to water contaminated with feces of AI virus-inoculated Mallards (Anas platyrhynchos) to evaluate whether ingestion of exposed freshwater snails was an alternate route of AI virus transmission to waterfowl. None of the immunologically naïve Mallards developed an infection, indicating that transmission via ingestion likely did not occur. Our results suggest that this particular trophic interaction may not play an important role in the transmission of AI viruses in aquatic habitats.
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http://dx.doi.org/10.7589/2012-04-111DOI Listing
October 2013

At-sea behavior varies with lunar phase in a nocturnal pelagic seabird, the swallow-tailed gull.

PLoS One 2013 26;8(2):e56889. Epub 2013 Feb 26.

Department of Migration and Immuno-Ecology, Max Planck Institute for Ornithology, Radolfzell, Baden-Württemberg, Germany.

Strong and predictable environmental variability can reward flexible behaviors among animals. We used long-term records of activity data that cover several lunar cycles to investigate whether behavior at-sea of swallow-tailed gulls Creagrus furcatus, a nocturnal pelagic seabird, varied with lunar phase in the Galápagos Islands. A Bayesian hierarchical model showed that nighttime at-sea activity of 37 breeding swallow-tailed gulls was clearly associated with changes in moon phase. Proportion of nighttime spent on water was highest during darker periods of the lunar cycle, coinciding with the cycle of the diel vertical migration (DVM) that brings prey to the sea surface at night. Our data show that at-sea behavior of a tropical seabird can vary with environmental changes, including lunar phase.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0056889PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582633PMC
August 2013

Freshwater clams as bioconcentrators of avian influenza virus in water.

Vector Borne Zoonotic Dis 2012 Oct 27;12(10):904-6. Epub 2012 Aug 27.

United States Department of Agriculture/Animal and Plant Health Inspection Service (USDA/APHIS) Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado, USA.

We report experimental evidence for bioconcentration of a low-pathogenicity avian influenza virus (H6N8) in the tissue of freshwater clams. Our results support the concept that freshwater clams may provide an effective tool for use in the early detection of influenza A viruses in aquatic environments.
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http://dx.doi.org/10.1089/vbz.2012.0993DOI Listing
October 2012

Evaluation of management treatments intended to increase lamb recruitment in a bighorn sheep herd.

J Wildl Dis 2012 Jul;48(3):781-4

Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect Road, Fort Collins, Colorado 80526, USA.

We administered a suite of treatments to a herd of Rocky Mountain bighorn sheep (Ovis canadensis canadensis) that was experiencing poor lamb recruitment and showing signs of respiratory disease. Despite 3 yr of treatment with various combinations of anthelmentics, antibiotics, vaccines, and hyperimmune serum products, recruitment was not improved.
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http://dx.doi.org/10.7589/0090-3558-48.3.781DOI Listing
July 2012

Avian influenza viruses in wild land birds in northern Vietnam.

J Wildl Dis 2012 Jan;48(1):195-200

Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Campus Delivery 1474, Fort Collins, Colorado 80523, USA.

Given a paucity of data on the occurrence of avian influenza viruses (AIVs) in wild passerines and other small terrestrial species in Southeast Asia and the importance of highly pathogenic Asian-strain H5N1 outbreaks in humans and domestic poultry in these areas, we focused on surveillance for influenza A viral nucleic acids and antibodies for AIVs in wild-caught birds in northern Vietnam. Four of 197 serum samples collected in 2007 from Black-crested Bulbul (Pycnonotus melanicterus), Crow-billed Drongo (Dicrurus annectans), Buff-breasted Babbler (Pellorneum tickelli), and Black-browed Fulvetta (Alcippe grotei) were antibody positive for the H5 subtype. Fourteen of 193 samples collected in 2008 were positive for the influenza A viral M gene by real-time reverse transcriptase-polymerase chain reaction. These included samples from 10 Japanese White-eyes (Zosterops japonicus), two Puff-throated Bulbuls (Alophoixus pallidus), one White-tailed Robin (Cinclidium leucurum), and one Striped Tit-babbler (Macronous gularis). Almost all positive samples were from bird species that forage in flocks, including Japanese White-eyes with an unusually high prevalence of 14.9%. We collected samples from birds from three habitat types but detected no strong pattern in prevalence. Our results suggest that attention should be given to terrestrial species, particularly flocking passerines, in AIV surveillance and monitoring programs.
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http://dx.doi.org/10.7589/0090-3558-48.1.195DOI Listing
January 2012

Toxoplasma gondii in circumpolar people and wildlife.

Vector Borne Zoonotic Dis 2012 Jan 13;12(1):1-9. Epub 2011 Oct 13.

Department of Veterinary Microbiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

Despite extensive worldwide surveillance in populations of both people and wildlife, relatively little is known about Toxoplasma gondii ecology in the circumpolar north. Many northern animals and people demonstrate exposure to T. gondii, but the apparent low densities of domestic or wild felids suggest that additional transmission mechanisms are responsible for T. gondii persistence in high latitudes, whether remote source (from another region), vertical, or dietary. People in these northern communities who practice subsistence hunting might have an increased infection risk due to traditional food preparation techniques and frequent handling of wild game. Recent advances in T. gondii genotyping, understanding of host-parasite relationships, and increased human and wildlife surveillance will help to address knowledge gaps about parasite evolution, distribution, and abundance throughout the Arctic and Subarctic.
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http://dx.doi.org/10.1089/vbz.2011.0705DOI Listing
January 2012

Experimental inoculation of house sparrows (Passer domesticus) with buggy creek virus.

J Wildl Dis 2008 Apr;44(2):331-40

Department of Biological Science, University of Tulsa, Tulsa, Oklahoma 74104, USA.

We performed experimental inoculations of house sparrows (Passer domesticus) with Buggy Creek virus (BCRV), a poorly known alphavirus (Togaviridae) vectored primarily by the swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) that is an ectoparasite of the cliff swallow (Petrochelidon pyrrhonota) and house sparrow. Viremias were detected by plaque assay in two of six birds on days 1-3 postinoculation; viremia was highest on day 2. Viral RNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in blood of six of 12 birds ranging from day 1 to day 15 postinoculation. Infectious BCRV was detected in nasopharyngeal swab samples from two birds by plaque assay. Three control birds that were housed with viremic individuals showed evidence of BCRV RNA in blood (by RT-PCR), suggesting possible bird-to-bird transmission of this virus. Viral RNA also was detected by RT-PCR in brain and skin tissue of six birds on necropsy at the end of the 16-day experiment. Introduced house sparrows are apparently a competent amplifying host for BCRV, and their presence year-round at cliff swallow colonies may facilitate persistence of the virus locally, especially when cliff swallows abandon a site temporarily. The findings that BCRV can be shed orally, that it persists in bird skin, and that control birds could apparently be infected by conspecifics suggest that this virus may be transmitted from bird to bird in the crowded conditions of many cliff swallow colonies.
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http://dx.doi.org/10.7589/0090-3558-44.2.331DOI Listing
April 2008

Hematology, plasma chemistry, serology, and Chlamydophila status of the waved albatross (Phoebastria irrorata) on the Galapagos Islands.

J Zoo Wildl Med 2003 Sep;34(3):278-83

Saint Louis Zoological Park, 1 Government Drive, St. Louis, Missouri 63110, USA.

Venipuncture was performed on 50 adult, free-ranging waved albatrosses (Phoebastria irrorata) on Española, Galapagos Islands, Ecuador, to establish hematologic and plasma biochemistry reference ranges and to determine the prevalence of exposure to important domestic avian pathogens. Weights and plasma creatine phosphokinase activities differed significantly between males and females. Serum was tested for evidence of exposure to avian influenza, avian paramyxoviruses 1, 2, and 3, avian cholera, adenovirus groups 1 and 2, avian encephalomyelitis, Marek's disease, infectious bursal disease, and infectious bronchitis virus (Connecticut and Massachusetts strains). Of 44 birds, 29 (66%) seroreacted to adenovirus group 1, and four seroreacted to avian encephalomyelitis. Cloacal swabs were negative for Chlamydophila psittaci DNA.
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http://dx.doi.org/10.1638/02-076DOI Listing
September 2003
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