title: Multi-scale occupancy approach to estimate Toxoplasma gondii prevalence and detection probability in tissues: an application and guide for field sampling.
abstract: 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.
authors.affiliation: Department of Veterinary Microbiology, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada; Department of Fish, Wildlife, and Conservation Biology, Colorado State University, 1474 Campus Delivery, Fort Collins, CO 80523, USA. Electronic address: elmore.stacey@gmail.com.
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: Bureau of Microbial Hazards, Health Canada, 251 Sir Frederick Banting Driveway, Ottawa, Ontario K1A 0K9, Canada.
authors.forename: Asma
authors.initials: A
authors.lastname: Iqbal
authors.affiliation: Department of Microbiology, University of Tennessee, M409 Walters Life Sciences, Knoxville, TN 37996, USA.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Su
authors.affiliation: Bureau of Microbial Hazards, Health Canada, 251 Sir Frederick Banting Driveway, Ottawa, Ontario K1A 0K9, Canada.
authors.forename: Brent R
authors.initials: BR
authors.lastname: Dixon
authors.affiliation: Prairie and Northern Research Centre, Environment Canada, 115 Perimeter Road, Saskatoon, Saskatchewan S7N 0X4, 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 S7N 2R3, 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 S7N 5B4, Canada.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Jenkins
mesh_terms: D000818:Animals; D001110:Arctic Regions; D001921:Brain / Q000469:parasitology; D002170:Canada / Q000453:epidemiology; D002645:Chickens / Q000469:parasitology; D016054:DNA, Protozoan / Q000235:genetics; D005777:Geese / Q000469:parasitology*; D006321:Heart / Q000469:parasitology; D011201:Poultry Diseases / Q000453:epidemiology / Q000469:parasitology*; D015995:Prevalence; D011336:Probability; D014122:Toxoplasma / Q000235:genetics / Q000302:isolation & purification*; D014124:Toxoplasmosis, Animal / Q000453:epidemiology / Q000469:parasitology*
chemical_list: D016054:DNA, Protozoan
keywords: Arctic; Occupancy modelling; Ross’s goose; Snow goose; Tissue detection; Toxoplasma