Echinococcus multilocularis are gut-dwelling parasitic tapeworms of carnivores (foxes, coyotes, dogs, etc.). Eggs of E. multilocularis that are shed in the feces of canids are then ingested by various rodent species (intermediate hosts) in which they develop as cysts in the internal organs. The life-cycle continues when the infected rodent is ingested by a carnivore. Humans are dead-end intermediate hosts with a case fatality rate that can be greater than 90%, if left untreated.
Last year, the research group of Dr. Alessandro Massolo at the University of Calgary, Faculty of Veterinary Medicine, reported the occurrence of E. multilocularis in coyotes in Calgary. More recently, by monitoring the infections in rodents in the city of Calgary, this group found a case of severe echinococcosis in a southern red-backed vole (Myodes gapperi), a species never reported before as an intermediate host for E. multilocularis (report available online). These results suggest that M. gapperi may play a role in the establishment and maintenance of the life-cycle of E. multilocularis in wild animals in urban landscapes. Preliminary data from the same group indicate that the meadow vole (Microtus pennsylvanicus) and deer mouse (Peromyscus maniculatus) may also act as intermediate hosts for the parasite in the city of Calgary. This research group continues to survey for other potential small mammal intermediate hosts in Calgary.
In the Northern Hemisphere, reported increase in the parasite geographic range and its prevalence seem to suggest a possible emergence of this zoonosis, although the simultaneous increase of surveillance efforts would call for prudence when interpreting trends. The overall research carried out by Dr. Massolo’s group aims to shed light on potential for transmission for E. multilocularis among coyotes, dogs and eventually humans in urban settings. Surveillance of this potentially emergent zoonosis will lead to a better understanding of the disease and will provide landscape planners and managers with information necessary for science-based intervention strategies aimed to reduce and manage transmission risks.