New geographic records for Echinococcus canadensis in coyotes and moose from Nova Scotia, Canada

Human echinococcosis incidence in Canada: A retrospective descriptive study using administrative hospital and ambulatory visit data, 2000-2020

Background

Echinococcosis is a zoonotic disease caused by the ingestion of tapeworm eggs shed by canids. The potential recent establishment of a more virulent European-type strain may be impacting human echinococcosis in Canada, yet information is limited.

Objective

Administrative hospital and ambulatory visit data were used to provide a baseline of human echinococcosis cases in Canada between 2000-2020.

Methods

Canadian Institute of Health Information's Discharge Abstract Database, Hospital Morbidity Database and National Ambulatory Care Reporting System were combined to identify cases. Risk ratios (RR) by demographic factors and cumulative incidences (CIN) over place and time were calculated.

Results

A total of 806 echinococcosis cases were identified in Canada between 2000-2020, for a mean annual CIN of 1.3 cases per million population. Over the two decades, the mean annual CIN of cases increased nationally (1.3-1.4 cases per million), in the Northwest Territories (6.3-9.1 cases per million), in Alberta (1.5-2.4 cases per million) and in the Atlantic provinces (0.2-0.6 cases per million). Those from the Territories had the highest risk of echinococcosis (RR 17.1; 95% confidence interval: 8.7-33.7).

Conclusion

Though explanations are multifactorial, the new European-type strain may have a role in the small absolute increase in echinococcosis CIN in Canada observed over the study period. The CIN is likely underestimated and the validity of administrative data for analyzing zoonoses warrants investigation. Though this study contributes important awareness and a baseline, improved data are needed to clarify the effects of the new strain and inform public health response.

Prevalence and geographic distribution of Echinococcus genus in wild canids in southern Québec, Canada

Echinococcus spp. is an emerging zoonotic parasite of high concern. In Canada, an increase in the number of human and animal cases diagnosed has been reported, but information regarding the parasite's distribution in wildlife reservoir remains limited. A cross-sectional study was conducted to estimate the prevalence of wild canids infected with Echinococcus spp. and Echinococcus multilocularis in areas surrounding populated zones in Québec (Canada); to investigate the presence of areas at higher risk of infection; to evaluate potential risk factors of the infection; and as a secondary objective, to compare coproscopy and RT-PCR diagnostic tests for Taenia spp. and Echinococcus identification. From October 2020 to March 2021, fecal samples were collected from 423 coyotes (Canis latrans) and 284 red foxes (Vulpes vulpes) trapped in 12 administrative regions. Real-time PCR for molecular detection of genus Echinococcus spp. and species-specific Echinococcus multilocularis were performed. A total of 38 positive cases of Echinococcus spp., of which 25 were identified as E. multilocularis, were detected. Two high-risk areas of infection were identified. The prevalence of Echinococcus spp. was 22.7% (95% CI 11.5-37.8%) in the Montérégie centered high-risk area, 26.5% (95% CI 12.9-44.4%) in the Bas-St-Laurent high-risk area, and 3.0% (95%CI 1.8-4.7%) outside those areas. For E. multilocularis, a prevalence of 20.5% (95% CI 9.8-35.3%) was estimated in the high-risk area centered in Montérégie compared to 2.4% (95% CI 1.4-3.9%) outside. Logistic regression did not show any association of infection status with species, sex, or geolocation of capture (p > 0.05). This study shows the circulation of Echinococcus in a wildlife cycle in 9/12 administrative regions of Québec.

New Geographic Records for Trichinella nativa and Echinococcus canadensis in Coyotes (Canis latrans) from Insular Newfoundland, Canada

Coyotes (Canis latrans) rapidly expanded across North America during the 20th century and in 1987 colonized insular Newfoundland, Canada. Their arrival brought the potential for new predator-prey interactions and the potential for transmission of parasites to naïve populations. Trichinella spp. and Echinococcus spp. are zoonotic parasites not previously reported from the island of Newfoundland, Canada. Muscle samples (diaphragm and tongue) from 153 coyotes and feces from 35/153 coyotes were collected. Larvae of Trichinella spp. were recovered by muscle digestion from 6/153 coyotes (3.9%) and identified using multiplex PCR and Sanger sequencing as T. nativa. Fecal samples were screened for DNA of Echinococcus spp. using qPCR, and intestines from positive animals were examined for adult cestodes. No fecal samples were positive for DNA of E. multilocularis, and 2/35 (5.7%) samples were positive for E. canadensis, of which one was successfully genotyped as the G10 cervid strain. Echinococcus canadensis has not previously been reported on the island of Newfoundland, historically the only region of Canada where Echinococcus spp. was not known to occur. No species of Trichinella have previously been reported on the island. Both parasites are zoonotic, and hunters, trappers, dog owners, and the general public should be aware of these new risks for public health.