title: Toxoplasma gondii exposure in arctic-nesting geese: A multi-state occupancy framework and comparison of serological assays.
abstract: 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.
authors.affiliation: Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N5B4, Canada.
authors.forename: Stacey A
authors.initials: SA
authors.lastname: Elmore
authors.affiliation: Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO 80523, USA.
authors.forename: Kathryn P
authors.initials: KP
authors.lastname: Huyvaert
authors.affiliation: Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO 80523, USA.
authors.forename: Larissa L
authors.initials: LL
authors.lastname: Bailey
authors.affiliation: Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO 80523, USA.
authors.forename: Jared
authors.initials: J
authors.lastname: Milhous
authors.affiliation: Prairie and Northern Research Centre, Environment Canada, 115 Perimeter Road, Saskatoon, Saskatchewan S7N0X4, Canada.
authors.forename: Ray T
authors.initials: RT
authors.lastname: Alisauskas
authors.affiliation: Centre for Food-Borne and Animal Parasitology, Canadian Food Inspection Agency, 116 Veterinary Road, Saskatoon, Saskatchewan S7N2R3, Canada.
authors.forename: Alvin A
authors.initials: AA
authors.lastname: Gajadhar
authors.affiliation: Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N5B4, Canada.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Jenkins
keywords: Agglutination test; DAT occupancy estimation; IFAT; Lesser Snow Goose; MAT; Ross’s Goose; Toxoplasma gondii