Ecological Investigation Of
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ECOLOGICAL INVESTIGATION OF A NEW HOST-PARASITE RELATIONSHIP: PARELAPHOSTRONGYLUS ODOCOILEI IN THINHORN SHEEP (OVIS DALLI) A Thesis Submitted to the College of Graduate Studies and Research In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy In the Department of Veterinary Microbiology University of Saskatchewan Saskatoon By EMILY JOAN JENKINS Keywords: protostrongylid, geographic distribution, molecular identification, pathogenesis, neurological syndrome, pneumonia, larval bionomics, degree day model, epidemiology, climate change © Copyright Emily Joan Jenkins, August 2005. All rights reserved. College Building, University of Saskatchewan Used with permission of James E. Mills, Saskatoon Permission to Use In presenting this thesis in partial fulfilment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other use of material in this thesis in whole or part should be addressed to: Head of the Department of Veterinary Microbiology University of Saskatchewan Saskatoon, Saskatchewan (S7N 5B4) iii ABSTRACT Discovery of a new host-parasite relationship, Parelaphostrongylus odocoilei in Dall’s sheep (Ovis dalli dalli) in the Canadian North, prompted the first investigation of the geographic distribution, pathogenesis, ecology and epidemiology of this parasite, as well as the related protostrongylid Protostrongylus stilesi, at Subarctic latitudes (60-65ºN). All protostrongylid parasites have an indirect life-cycle, where first-stage larvae are shed in the feces of a mammalian definitive host, penetrate the foot of a gastropod intermediate host, and develop to infective third-stage larvae. Protostrongylid larvae were recovered from over 2000 fecal samples from thinhorn sheep (Ovis dalli) and other hosts for P. odocoilei and P. stilesi across northwestern North America (38-69 ºN). Through novel application of molecular techniques to identify morphologically indistinguishable first-stage larvae, new records for P. odocoilei were established at 20 locations. This provided insight into the historical origins and biogeography of this new host-parasite relationship, and greatly expanded the known geographic range of both protostrongylids. Clinical effects, including a neurological syndrome, were described in five thinhorn sheep experimentally infected with P. odocoilei. Neural and respiratory pathology in these five sheep were compared with over 50 wild Dall’s sheep from a population naturally infected with P. odocoilei and P. stilesi. In the end stages, diffuse verminous interstitial pneumonia associated with P. odocoilei led to respiratory failure, and may have acted as a predisposing factor for bacterial pneumonia, which caused sporadic mortalities in this wild population. At Subarctic latitudes, seasonal patterns in host and parasite availability, including larval shedding by Dall’s sheep and larval development in experimentally infected gastropods, suggested that lambs become infected with P. odocoilei in a narrow seasonal window in their first fall on winter range. In combination with laboratory experiments, a degree day model for iv temperature-dependent larval development was developed, validated, and applied to describe and predict the effects of climate warming on protostrongylid parasites of thinhorn sheep in northern North America. In a future of climate warming, the narrow seasonal window for parasite development and transmission would be significantly extended, leading to amplification of populations of P. odocoilei and P. stilesi in endemic regions, and possibly range expansion of P. odocoilei. This may have consequences for the health of thinhorn sheep, as well as other wildlife that are important resources in the Canadian North. v ACKNOWLEDGMENTS This scientific investigation was a journey of exploration and self-discovery that took me from the laboratory bench to remote regions of the Canadian North. I did not undertake this journey alone. Thank you to all those who traveled with me, encouraged me through the inevitable periods of lonely tedium, and celebrated the serendipitous discoveries with me. Many individuals (who populate the co-author and acknowledgement sections of the chapters ahead) contributed to the formation of this thesis and this student, especially my advisory committee: Lydden Polley, Eric Hoberg, Greg Appleyard, Ted Leighton, Vikram Misra, Brett Elkin, and honorary members Susan Kutz and Alasdair Veitch. Others who have shared advice, information, and inspiration include Trent Bollinger, Neil Chilton, Murray Lankester, John Nagy, John Nishi, Margo Pybus, Bill Samuel, Helen Schwantje, Gary Wobeser, and Randy Zarnke. As well, I thank fellow graduate students (including Sherry Hannon and Cathy Soos), members of the Disease Ecology group, and the Gwenna Moss Teaching and Learning Centre. At the Western College of Veterinary Medicine (WCVM), I thank members of the Canadian Cooperative Wildlife Health Centre, Prairie Diagnostic Services, and various departments for their innovation and assistance in maintaining and monitoring an unusual wildlife species. These include staff of the Animal Care Unit (Monique Burmester, Kyle Constantinoff, Marlow Thue, and Doug Walde); parasitology technicians (Mathew Herperger and Brent Wagner) and employees (Jennifer Dodd, Farhad Ghandi, Darren Harder, and Jeremy Thomas); PCR technicians (Rebecca Cross, Anita Quon, and Anju Tumber); veterinary clinicians, technicians, and students (Brenda Beierle, Carol Black, Nigel Caulkett, Chris Clark, Paul Crawford, Elena Garde, Sarah Lightfoot Wagner, Sharon Martin, Marcello Martinez, Matt Read, Jennifer Skific, and Kim Tryon); and researchers (Manuel Chirino-Trejo and Keith West). From the Department of Medicine, I thank Tom Hurst, Joe Mink, and Michelle Moroz, as well as the Department of vi Medical Imaging at the Royal University Hospital, including radiologists Kendra Fisher and Derek Fladeland. Images in this thesis were produced with the help of the parasitology technicians, as well as Ian Shirley and Juliane Deubner. Many outfitters, guides, resident, and non-resident hunters in the remote Mackenzie Mountains, NT, as well as wildlife officers, technicians, and pilots, were instrumental in surveillance, collection of samples, and logistics. I especially thank my “family” at Palmer Lake, Bill and Carol McKenzie and the Grinde family (Gana River Outfitters), without whom this research would not have been possible. I also thank Ariel Brunn, Ken Davidge, Aaron Genest, Richard Popko, Jenny Skific, Michelle Swallow, and Arianna Zimmer, for invaluable assistance in the field and many shared adventures. This project was funded by the following organizations: Arctic Institute of North America; Association of Mackenzie Mountain Outfitters; Canadian Wildlife Federation; Department of Environment and Natural Resources (previously Department of Resources, Wildlife and Economic Development), Government of the Northwest Territories; Foundation for North American Wild Sheep, national and regional chapters of Alberta, Iowa, Utah, and Washington; Fraternity of the Desert Bighorn; Northern Scientific Training Program, Government of Canada; Safari Club International (Pittsburgh Chapter); WCVM Interprovincial Graduate and Undergraduate Student Fellowships; WCVM Wildlife Health Fund; and the Wild Sheep Society of British Columbia. vii Dedication To my family, especially my husband, Aaron Genest, for unflagging support and a life-saving sense of humor. “Never about imposing a thesis, only about seeking truth.” Ken Alexander, The Walrus, May 2005 Written in memory of journalist Bill Cameron, but equally applicable to my grandfather, Bill Jenkins, and my friend, Bill Sarjeant, who told stories, many of which were true, and many of which should have been. TABLE OF CONTENTS page ABSTRACT....................................................................................................................... iv ACKNOWLEDGMENTS ................................................................................................. vi LIST OF TABLES............................................................................................................ xii LIST OF FIGURES ......................................................................................................... xiv LIST OF ABBREVIATIONS......................................................................................... xvii 1 INTRODUCTION ............................................................................................................... 1 1.1 Background and discovery.............................................................................. 1 1.2 Host range and geographic distribution .......................................................... 3 1.3 Development