A Spatial Epidemiological Analysis of Human and Bovine Cryptosporidiosis in Southern Ontario, from 2011 to 2014

Cryptosporidium is a parasitic zoonotic pathogen that can result in human and animal morbidity and mortality and has been detected in Southern Ontario— an area densely populated by humans and cattle. This thesis is a study of the spatial distribution of human and bovine cryptosporidiosis across 29 Public Health Unit areas in Southern Ontario from 2011 to 2014. The overall raw farm-level prevalence of bovine cryptosporidiosis was 45% [95% CI: 42%-48%]. The raw cumulative incidence risk of human cryptosporidiosis was 6.91 [95%CI: 6.47-7.39] cases per 100,000 population. Overlapping disease clusters of both human and bovine cryptosporidiosis were identified in the Central West region of Southern Ontario. A Spatial Poisson regression showed that the incidence risk ratio of cryptosporidiosis in humans increases with increasing dairy cattle density. These findings suggest that dairy cattle play a role in the distribution of human cryptosporidiosis. Further studies on the transmission of cryptosporidiosis in Southern Ontario and the specific role of dairy cattle are warranted.