Molecular epidemiology and diagnostics for Echinococcus multilocularis in canid definitive and intermediate hosts
Date
2023-04-17
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-0322-8954
Type
Thesis
Degree Level
Doctoral
Abstract
Echinococcus multilocularis shed by canid definitive hosts causes alveolar echinococcosis (AE) in rodent intermediate hosts as well as human and dog aberrant hosts. AE is debilitating in humans and dogs, resulting in serious health challenges and expenses for both veterinary and public health. This thesis addresses needs to improve molecular and serological diagnostics for E. multilocularis in wild canids and dogs. I adapted and evaluated an in-house copro-qPCR-MCA which has comparable diagnostic sensitivity and specificity with the ‘gold standard’ adult cestode recovery, and superior diagnostic sensitivity (92% vs 39%) when compared to conventional fecal flotation techniques. I demonstrated E. multilocularis prevalence of 72% in coyotes in Saskatchewan, a highly endemic region, and using the copro-qPCR-MCA, 17% in coyotes from a newly endemic and highly populated area of British Colombia, and 10% in foxes from islands in the western Canadian Arctic. I also demonstrated parasite stage specificity of the Em95 antigen for serological diagnosis of canine AE in coyotes with intestinal infections, suggesting that serology for the Em95 antigen is likely to be an excellent tool for detecting cases of AE in dogs in North America, where this disease is increasingly described. My thesis also described 27 cases of canine AE from western Canada, highlighting important clinical, epidemiological, and economic information for veterinary practitioners and dog owners and indicating that dogs with AE may serve as indicators of parasite range expansion and risk to humans. Finally, molecular epidemiology revealed that the haplotypes present in intestines of wild canids and AE cases in dogs and humans in prairie regions of western Canada are highly pathogenic and zoonotic European strains, compared to the N2 strain previously described in central North America. In the western Canadian Arctic, my thesis reports, for the first time, that the established haplotype of E. multilocularis is N1 North American Arctic strain, and not Asian strains reported from the west coast of Alaska, nor the N2 or European strains established in populated regions of southern Canada. Therefore, the Canadian Arctic remains vulnerable to introduction of Asian and European strains with higher zoonotic potential. This thesis provides useful diagnostic tools for large scale prevalence studies of E. multilocularis in canids, as well as data on the molecular epidemiology and prevalence which can guide the formulation of control and prevention policies.
Description
Keywords
Diagnosis, Echinococcosis, Molecular epidemiology, Polymerase chain reaction, Zoonosis
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Veterinary Microbiology
Program
Veterinary Microbiology