Surveillance for Echinococcus canadensis genotypes in Canadian ungulates

Abstract

The geographic and host distribution, prevalence and genotypes of Echinococcus canadensis in wild ungulates in Canada are described to better understand the significance for wildlife and public health. We observed E. canadensis in 10.5% (11/105) of wild elk (wapiti; Cervus canadensis) in Riding Mountain National Park, Manitoba, examined at necropsy, over two consecutive years (2010-2011). Molecular characterization of hydatid cyst material from these elk, as well as three other intermediate wildlife host species, was based on sequence of a 470bp region of the NADH dehydrogenase subunit 1 (NAD1) mitochondrial gene. In moose [Alces alces], elk, and caribou [Rangifer tarandus] from northwestern Canada, the G10 genotype was the only one present, and the G8 genotype was detected in a muskox (Ovibos moschatus) from northeastern Canada. On a search of the national wildlife health database (1992-2010), cervids with hydatid cysts were reported in all provinces and territories except the Atlantic provinces, from which wolves [Canis lupis] are historically absent. Of the 93 cervids with records of hydatid cysts, 42% were elk, 37% were moose, 14% were caribou, and 6% were white-tailed and mule deer [Odocoileus virginianus and Odocoileus hemonius]. In these animals, 83% of cysts were detected in lungs alone, 8% in both lungs and liver, 3% in liver alone, and 6% in other organs. These observations can help target surveillance programs and contribute to a better understanding of ecology, genetic diversity, and genotype pathogenicity in the Echinococcus granulosus species complex.