Browsing by Author "Meyers, Olivia"

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    Molecular detection and distribution of Fascioloides magna and its snail host in Elk Island National Park
    (2024-09-20) Meyers, Olivia; Pruvot, Mathieu; Kutz, Susan; Gilleard, John; Maraj, Ramona
    Giant liver fluke (Fascioloides magna) is a parasitic worm found in wild and domestic ruminants in North America. Infection with F. magna, known as fascioloidiasis, causes liver damage, fibrosis, and inflammation that can negatively impact the fitness of hosts. In Elk Island National Park (EINP), Alberta, Canada, this parasitic disease is suspected to contribute to the ongoing moose population decline. To manage the park’s moose population, fluke control measures, including anthelmintic treatment and environmental control strategies, can reduce the prevalence of fascioloidiasis. However, efficient, targeted interventions require knowledge on the fine-scale distribution of the parasite. In this thesis, I investigated the epidemiology of F. magna to guide an effective and minimally invasive fluke control program in EINP. First, I developed and validated a molecular assay to detect F. magna in freshwater snails. A multiplex qPCR assay was created to specifically target F. magna as well as an internal amplification control endogenous to freshwater snails. I used this assay, along with its constituent singleplex assay, to diagnose F. magna infections in lymnaeid snails from EINP. The singleplex assay proved to be more sensitive than the multiplex, making it a more accurate tool for epidemiological surveys. Stagnicola elodes was identified as an intermediate host species of F. magna in EINP, with an estimated prevalence of 5.8%. Second, I determined the spatial distribution of F. magna and its snail host in EINP and assessed whether environmental factors could predict their occurrence among water bodies. I found that snail hosts for F. magna were generally widespread across the park and were associated with physiochemical and plant-related environmental indicators at water bodies. Snail infections with F. magna were relatively rare, observed at only 12% of sites. Using remote-sensing environmental data, I created fine-scale predictive models to forecast the occurrence of snail hosts and F. magna-infected snails across water bodies. However, these predictive occupancy models demonstrated poor predictive accuracy. This work has contributed a molecular tool for the surveillance of F. magna, explored the utility of ecological niche modeling for the epidemiological control of the parasite, and furthered our understanding of fascioloidiasis in EINP.