Assessing the potential for infections of Echinococcus multilocularis in dogs in a hotspot of human alveolar echinococcosis infections in North America

Risk factors for Echinococcus multilocularis intestinal infections in owned domestic dogs in a North American metropolis (Calgary, Alberta)

Human alveolar echinococcosis is increasingly documented in Alberta, Canada. Its causative agent, Echinococcus multilocularis (Em), can be transmitted to humans by infected dogs. We assessed the prevalence and associated risk factors for Em infections in domestic dogs in Calgary, Alberta, Canada. In this cross-sectional study that coupled collection and assessment of dog feces with a survey on potential risk factors, 13 of 696 (Bayesian true prevalence, 2.4%; 95% CrI: 1.3-4.0%) individual dogs' feces collected during August and September 2012 were qPCR positive for Em. Sequencing two of these cases indicated that both were from the same Em European strain responsible for human infections in Alberta. Likelihood of intestinal Em was 5.6-times higher in hounds than other breeds, 4.6-times higher in dogs leashed at dog parks than those allowed off-leash, 3.1-times higher in dogs often kept in the backyard during spring and summer months than those rarely in the yard, and 3.3-times higher in dogs living in neighbourhoods bordering Bowmont park than those in other areas of Calgary. This situation warrants surveillance of dog infections as a preventative measure to reduce infections in North America.

Host spatiotemporal overlap in a park with high endemicity of Echinococcus multilocularis

Background

There has been a spate of recent cases of human alveolar echinococcosis (AE) in Alberta, Canada. Alveolar echinococcosis is caused by Echinococcus multilocularis, which is prevalent among coyote populations and present in domestic dogs in Alberta.

Methods and results

Using qPCR, we estimated the seasonal fecal prevalence of E. multilocularis in coyotes and dogs in a multiuse recreation area close to Edmonton, Alberta, where we also setup remote cameras to model seasonal changes in the overlap in temporal activity and the spatial intensity of use among coyotes, humans, and dogs, as a proxy of potential transmission. We detected E. multilocularis in 18 of 137 wild canid feces and none in 44 dog feces. After correcting for the qPCR test's sensitivity and specificity, we estimated at 15.7% (9.7-22.7%, 95% CrI) the true fecal prevalence for coyotes. Temporal overlap between coyotes and both humans and dogs increased in the fall and winter relative to the spring and summer. Coyote intensity of use showed seasonal variations and was higher on maintained trails and locations closer to visitor parking and at sites with high intensity of dog use.

Conclusions

Our results reinforce the need of an integrated approach, typical of both One-Health and Eco-Health, to park management for minimizing the likelihood of transmission where human and dog activity results in significant overlap with the one of the natural definitive hosts of zoonotic parasites.

Canine Alveolar Echinococcosis: An Emerging and Costly Introduced Problem in North America

Alveolar echinococcosis (AE), caused by the metacestode of Echinococcus multilocularis, is emerging in both dogs and people in North America. Here, we review 27 cases of canine AE opportunistically reported since the index case was described in 2009 in Western Canada. We describe clinical presentation, diagnosis, treatment, outcome, and source of canine infection, based on genetics of the parasite isolated from some canine cases. Diagnosis of AE was by histopathology and/or PCR on DNA extracted from metacestodes. The median age of dogs at diagnosis was 4 years (range 1-12), which is low compared to neoplasia, the most common differential diagnosis. There was no sex predilection and different breeds were involved, but there were a disproportionate number of boxers and beagles relative to their representation in the general canine population. The most common potential risk factors included contact with wildlife and visits to off leash areas. Abdominal distension was the most common clinical sign at presentation, and medical imaging generally revealed an abdominal mass. On histopathology, protoscoleces were observed in 7 out of 14 dogs. In 7 cases, DNA sequences were most similar to European (versus North American) haplotypes, identical to those recently reported in coyotes as definitive hosts in North America, and different between eastern and western North America, implying multiple introduction events. Dogs that were not treated (n = 6) had 16% survival in the first 100 days in comparison with 82% survival of treated dogs (n = 11). Direct costs to the owner of treating canine AE ranged from 1,317 to 12,655 CAD depending on the situation at the onset of treatment. This study provides important clinical, epidemiological, and economic information for veterinary practitioners and regulators for importation of dogs, and for public health, as dogs with AE may serve as indicators of parasite range expansion and risk to humans.

Canine nematode and Giardia spp. infections in dogs in Edmonton, Alberta, the "CANIDA" study

Background

Canine intestinal parasite prevalence may be influenced by geographical region, age, and health status of the dog. Behaviors such as predation, scavenging, or roaming as well as routine administration of anthelmintics also play a role. The purpose of this study was to evaluate fecal test results using zinc sulfate flotation by centrifugation combined with coproantigen testing directed at protein antigens excreted or secreted by hookworms (Ancylostoma spp. Uncinaria stenocephala), ascarids (Toxocara canis, Toxascaris spp. Baylisascaris spp.), whipworms (Trichuris vulpis), and Giardia spp. during active infection in owned dogs visiting dog parks in Western Canada.

Methods

A total of 774 participants were recruited from Edmonton, Alberta, Canada. Canine fecal samples were collected from seven dedicated off-leash dog parks. Participating dog owners responded to a questionnaire regarding their dogs’ signalment, previous veterinary history, and use of parasite-preventive products. Fecal samples were tested using zinc sulfate centrifugation combined with coproantigen testing.

Results

The overall prevalence of canine intestinal parasites in client-owned dogs was similar to previous studies conducted in the US. Mean age of dogs tested was 4 years, with puppies and older dogs having higher rates of infection than the mean. Fecal flotation centrifugation found 3.2% hookworm, ascarid, whipworm, and Giardia spp.-positive infections. Coproantigen testing identified 5.8% positive infections, including all of the above that were detected using fecal flotation centrifugation.

Conclusions

Coproantigen testing detected more hookworm, ascarid, whipworm, and Giardia spp.-positive samples in addition to detecting all positive results found using fecal flotation centrifugation. Fecal flotation centrifugation combined with coproantigen testing improves sensitivity over flotation alone and may detect pre-patent or sub-clinical infections in dogs visiting public dog parks.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05386-5.