Echinococcus multilocularis in Urban Coyotes, Alberta, Canada

Stefano Catalano¹, Manigandan Lejeune¹, Stefano Liccioli, Guilherme G. Verocai, Karen M. Gesy, Emily J. Jenkins, Susan J. Kutz, Carmen Fuentealba, Padraig J. Duignan, and Alessandro Massolo

Author affiliations: University of Calgary, Calgary, Alberta, Canada (S. Catalano, M. Lejeune, S. Liccioli, G.G. Verocai, S.J. Kutz, P.J. Duignan, A. Massolo); University of Saskatchewan, Saskatoon, Saskatchewan, Canada (K.M. Gesy, E.J. Jenkins); and Ross University, Basseterre, Saint Kitts, Saint Kitts, and Nevis (C. Fuentealba)

Abstract

Echinococcus multilocularis is a zoonotic parasite in wild canids. We determined its frequency in urban coyotes (Canis latrans) in Alberta, Canada. We detected E. multilocularis in 23 of 91 coyotes in this region. This parasite is a public health concern throughout the Northern Hemisphere, partly because of increased urbanization of wild canids.

Echinococcus multilocularis is the causative agent of alveolar echinococcosis in humans. This disease is a serious problem because it requires costly long-term therapy, has high case-fatality rate, and is increasing in incidence in Europe (1). This parasitic cestode has a predominantly wild animal cycle involving foxes (Vulpes spp.) and other wild canids, including coyotes (Canis latrans), as definitive hosts. However, it can also establish an anthropogenic life cycle in which dogs and cats are the final hosts. Rodents are the primary intermediate hosts in which the alveolar/multivesicular hydatid cysts grow and are often fatal. Humans are aberrant intermediate hosts for E. multilocularis (2).
In North America, E. multilocularis was believed to be restricted to the northern tundra zone of Alaska, USA, and Canada until it was reported in red foxes (Vulpes vulpes) from North Dakota, USA (3). This parasite has now been reported in the southern half of 3 provinces in Canada (Manitoba, Saskatchewan, and Alberta) and in 13 contiguous states in the United States (1).
Foxes are the traditional definitive hosts for E. multilocularis worldwide. However, in North America, coyotes may be prominent hosts, particularly when they are more abundant than foxes. E. multilocularis was reported in 7 (4.1%) of 171 coyotes in the northcentral United States in the late 1960s (3), and subsequently prevalences ranging from 19.0% to 35.0% have been reported in coyotes in the central United States (4).
In Canada, E. multilocularis was detected in 10 (23.0%) of 43 coyotes in Riding Mountain National Park, Manitoba (5). In Alberta, 1 case was recorded from the aspen parkland in 1973 (5) but it was not found in coyotes from forested regions and southern prairies (6,7). Nonetheless, E. multilocularis is generally considered enzootic to central and southern Alberta on the basis of its prevalence in rodent intermediate hosts. During the 1970s, sixty-three (22.3%) of 283 deer mice (Peromyscus maniculatus) trapped in periurban areas of Edmonton were positive for alveolar hydatid cysts (8), and E. multilocularis was also detected in 2 deer mice collected <1.8 km from Lethbridge in southern Alberta (9).
Because mice and voles (family Cricetidae, including Peromyscus spp.) have been reported as main prey (70.1%) of coyotes in Calgary (10), and coyotes are common in urban areas of Calgary and Edmonton, we suspected a role for this carnivore in the maintenance of the wild animal cycle of E. multilocularis in such urban settings. Thus, we aimed to ascertain the frequency of E. multilocularis in coyotes from metropolitan areas in Alberta, Canada.