A ONE HEALTH APPROACH TO ECHINOCOCCUS CANADENSIS AND OTHER PARASITIC ZOONOSES IN REMOTE, RURAL AND INDIGENOUS COMMUNITIES

Abstract

In Canada, parasitism in people and well-managed animal populations is less common now than a century ago, likely due to accessible anthelmintics, heightened public awareness, and improved sanitation. Some zoonotic parasites, such as Echinococcus canadensis are now rarely diagnosed in people, but persist mainly in northern populations where diagnostic services are limited. Veterinary services are also limited in these areas, and as a result, human and animal incidence data does not exist, is outdated, or underestimates the true incidence. We closed this knowledge gap in certain areas of western Canada by determining the prevalence of E. canadensis and other zoonotic parasites in wildlife (wolves [Canis lupus] and ungulates; Chapters 2 and 3), domestic dogs (Canis familiaris; Chapters 4 and 5), and people (Chapters 6-8). Using a One Health framework, we also explored parasite control practices and potential policy solutions for rural and remote communities (Chapters 8 and 9). During post-mortem examination, we observed E. canadensis in approximately 11% (11/105) of elk [Cervus canadensis], and 21% (34/165) of wolves. Our examination of historical post-mortem reports of ungulates demonstrated that E. canadensis is distributed throughout Canada, except for the high Arctic islands, the Maritime provinces, and the island of Newfoundland. Our analysis of dog feces collected throughout Saskatchewan suggested that patent taeniid (Taenia or Echinococcus spp.) infection was rare (0-4%), and that rural and northern dogs had higher endoparasitism than urban dogs. Sero-surveillance for four zoonoses (E. canadensis, Toxoplasma gondii, Trichinella, and Toxocara canis) by enzyme-linked immunosorbent assay indicated similar results - that people in northern SK (65% of 201) had higher exposure to one or more parasites than those in southern SK (12% of 113). Using patient health records, we reported annual incidence rates for clinical illness for the following zoonotic parasites: echinococcosis – 1.4/1 000 000; toxoplasmosis- 1.7/1 000 000; and toxocariasis-0.06/1 000 000. In the final chapter we compared the cost of treating human echinococcosis cases with a prevention program based on dosing dogs with praziquantel at 6 week intervals in the Kelsey Trail region, where human incidence is highest. Based on direct healthcare costs, such a program is not currently cost saving, but could become so if echinococcosis incidence increased. Preventative programs should be considered for high risk communities, which are often economically marginalized and lack appropriate resources to effectively control zoonotic parasitism. Putting One Health into action may require integrated human-animal healthcare services, introduction of community-based animal health workers, and increased transdisciplinary research to improve access to and uptake of preventative healthcare services for parasitic zoonoses in northern and remote communities.