Wild canids as sentinels for pathogens of public health and veterinary significance
Wild canids may serve as valuable sentinel species for emerging pathogens of public health and veterinary importance. However, for the full utility of a potential animal sentinel to be realized, it must be framed in the context of the pathogen ecology and surveillance objectives in question. This thesis was an investigation of wild canids and their relationship with two emerging pathogens that are of particular interest in Ontario: Echinococcus multilocularis and Dirofilaria immitis. Echinococcus multilocularis was detected in 23% (107/460) of wild canids tested from across the western, central, and eastern regions of southern Ontario, with an infection cluster identified in the central-west region comprised of ten contiguous public health units. These findings suggest a newly recognized endemic area for E. multilocularis in Canada. Additionally, we investigated the association of host-level (sex, body condition), environmental (southern Ontario region, landcover), temporal (season, hunting season, calendar year), and extraneous factors (submitter type) with E. multilocularis infection in coyotes in southern Ontario. We found body condition, natural landcover, and region to be associated with E. multilocularis infection in coyotes. With respect to Dirofilaria immitis infection, 4.8% (14/290) of wild canids were positive at necropsy. Cases were identified in two regions of southern Ontario: 12 were detected in the south-western region and two were detected in the eastern region. These data provide preliminary insights into the epidemiology of D. immitis in wild canids in southern Ontario. Additionally, we assessed the performance of the SNAP® 4Dx® Plus test for the detection of D. immitis antigen in wild canids by comparing results using lung tissue extract (LE) and thoracic fluid filter paper extract (TFE) samples with the necropsy-confirmed D. immitis status. The estimated sensitivity and specificity of the SNAP® 4Dx® Plus test for D. immitis antigen in LE was 80% and 98.9%, respectively. For the TFE, it was 70% and 97.9%, respectively. Collectively, the results indicate that the SNAP® 4Dx® Plus test is a suitable test for use with LE and TFE for the detection of D. immitis antigen in wild canids from southern Ontario.