Where have all the rabies cases gone? Results of rabies virus surveillance in wildlife in the Yukon, Canada

Abstract

Rabies continues to affect wildlife and domestic animals in northern Canada and Alaska, but no cases have been reported in the Yukon since the 1970s. To better understand the presence of rabies in the territory, a surveillance program began in 2009, using opportunistically collected samples from 13 species of wild mammals. Samples were collected from trapped wildlife through carcass collection programs, from animals that were found dead by the public, and those involved in human-wildlife conflict or in vehicle collisions. All samples (n=763) were negative for rabies virus antigen. Five (<1% of individuals tested) Arctic foxes (Vulpes lagopus), the primary reservoir of the Arctic rabies strain, were tested. Canada lynx (Lynx canadensis; n=290; 38%), wolverine (Gulo gulo; n=108; 14%), wolf (Canis lupus; n=105; 14%), red fox (Vulpes vulpes; n=90; 12%), and little brown bats (Myotis lucifugus; n=55; 7%) comprised the majority of animals sampled. Shifts in distributional ranges of species and movements of migratory populations or dispersing individuals, especially from adjacent jurisdictions where rabies is reported, may rapidly alter rabies transmission dynamics in the Yukon. Thus, more targeted surveillance of reservoir species, especially at jurisdictional borders, is recommended to monitor for changes in rabies prevalence in the Yukon.