Elmore Stacey A, Samelius Gustaf, Al-Adhami Batol, Huyvaert Kathryn P, Bailey Larissa L, Alisauskas Ray T, Gajadhar Alvin A, Jenkins Emily J
1 University of Saskatchewan, Department of Veterinary Microbiology, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada.
5 Colorado State University, Department of Fish, Wildlife, and Conservation Biology, 1474 Campus Delivery, Fort Collins, Colorado 80523-1474, USA.
J Wildl Dis. 2016 Jan;52(1):47-56. doi: 10.7589/2015-03-075.
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.
尽管原生动物寄生虫刚地弓形虫在全球范围内的鸟类和哺乳动物中普遍存在，但完整的宿主和传播途径尚未完全明确，尤其是在北极地区。尽管猫科终末宿主排出的卵囊传播机会明显有限，但北极地区人类和野生动物中刚地弓形虫的感染率可能很高。北极狐（Vulpes lagopus）面临着越来越大的人为和生态压力，导致其部分分布范围内的种群数量下降。我们对北极狐感染刚地弓形虫的了解仅限于少数几个地区，但已有该寄生虫导致死亡事件的报道。我们在加拿大努纳武特地区的毛德皇后湾候鸟保护区的卡拉克湖鹅群栖息地，对北极狐接触刚地弓形虫的情况进行了调查。按照占用模型框架，我们通过直接凝集试验（DAT）、间接荧光抗体试验（IFAT）以及一种可用于多种哺乳动物宿主物种的间接酶联免疫吸附测定（ELISA），对血清样本进行了重复抗体检测。作为检测性能的指标，我们随后估计了每种检测方法检测到刚地弓形虫抗体的概率。在此框架下，北极狐刚地弓形虫抗体的占用估计值在0.430至0.758之间。IFAT的检测概率最高（0.716），DAT（0.611）和ELISA（0.464）较低，这表明北极狐抗体检测的首选方法可能是IFAT。我们记录了北极狐接触刚地弓形虫的一个新地理记录，并展示了生态建模技术在解释野生动物物种诊断测试不完善性能方面的新应用。
