Molecular Evidence for Local Acquisition of Human Alveolar Echinococcosis in Saskatchewan, Canada.

Alveolar echinococcosis (AE) is a life-threatening parasitic disease caused by the zoonotic cestode Echinococcus multilocularis. Our goals were to confirm infection, identify species, and analyze biogeographical origin of metacestode tissues from a suspected human AE case in Saskatchewan, Canada. We conducted polymerase chain reaction (PCR) targeting the nad1 mitochondrial gene for E. multilocularis and the rrnS ribosomal RNA gene for E. granulosus and conducted haplotype analysis at the nad2 locus. Our analysis confirmed AE and indicated that sequences matched infected Saskatchewan coyotes and European E3/E4 haplotypes. The patient had no travel history outside North America. This suggests autochthonous transmission of a European-type strain.

Mistaken identity of an open reading frame proposed for PCR-based identification of Mycoplasma bovis and the effect of polymorphisms and insertions on assay performance.

Mycoplasma bovis is an important cause of disease in cattle and bison. Because the bacterium requires specialized growth conditions, many diagnostic laboratories routinely use PCR to replace or complement conventional isolation and identification methods. A frequently used target of such assays is the uvrC gene, which has been shown to be highly conserved among isolates. We discovered that a previously described PCR putatively targeting the uvrC gene amplifies a fragment from an adjacent gene predicted to encode a lipoprotein. Comparison of the lipoprotein gene sequence from 211 isolates revealed several single nucleotide polymorphisms, 1 of which falls within a primer-binding sequence. Additionally, 3 isolates from this group were found to have a 1,658-bp transposase gene insertion within the amplified region that leads to a false-negative result. The insertion was not detected in a further 164 isolates. We found no evidence that the nucleotide substitution within the primer-binding region affects the assay sensitivity, performance, or limit of detection. Nonetheless, laboratories utilizing this method for identification of M. bovis should be aware that the region amplified may be prone to nucleotide substitutions and/or insertions relative to the sequence used for its design and that occasional false-negative results may be obtained.

Application of direct polymerase chain reaction assays for Campylobacter fetus subsp. venerealis and Tritrichomonas foetus to screen preputial samples from breeding bulls in cow-calf herds in western Canada.

The primary objectives of this study were to estimate the prevalence of Campylobacter fetus subsp. venerealis (Cfv) and Tritrichomonas foetus in breeding bulls from a sentinel cohort of cow-calf herds in western Canada and to estimate the association between positive test status and non-pregnancy. The final objective was to evaluate the application of these tests when: i) screening bulls in the absence of a recognized problem with reproductive performance, and ii) testing for diagnosis of poor pregnancy rates. The crude apparent bull prevalence for Cfv was 1.1% [95% confidence interval (CI): 0.5% to 2.1%; 8/735] and herd prevalence was 2.6% (95% CI: 0.3% to 9.0%; 2/78). The crude apparent bull prevalence for T. foetus was < 0.001% (95% CI: 0.0% to 0.5%; 0/735) and herd prevalence was < 0.001% (95% CI: 0.0% to 4.6%; 0/78). Cows from herds where at least 1 bull was test positive for Cfv were 2.35 times more likely (95% CI: 1.01% to 5.48%; P = 0.047) to not be pregnant than those with no positive bulls. Polymerase chain reaction (PCR) testing of preputial material collected into phosphate-buffered saline (PBS) was recommended for screening for T. foetus when the pre-test probability of infection was > 1%. The same test for Cfv was not recommended for screening moderate- and low-risk herds due to the high risk of false positives. Tests for both T. foetus and Cfv can be used to investigate herds with reproductive problems when also ruling out other risk factors. Regardless of the type of test used, however, 3 negative tests are required to rule out infection in high-risk situations.

Les objectifs primaires de la présente étude étaient d'estimer la prévalence de Campylobacter fetus ssp. venerealis (Cfv) et Tritrichomonas foetus chez des taureaux reproducteurs d'une cohorte sentinelle issue de troupeaux vache-veau dans l'ouest canadien et d'estimer l'association entre un test positif et la non-gestation. L'objectif final était d'évaluer l'application de ces tests lors de : i) vérification des taureaux en absence d'un problème reconnu avec les performances de reproduction, et ii) épreuve diagnostique en présence de faibles taux de gestation. La prévalence apparente brute des taureaux pour Cfv était de 1,1 % [intervalle de confiance (IC) 95 % : 0,5 % à 2,1 %; 8/735] et la prévalence pour les troupeaux était de 2,6 % (IC 95 % : 0,3 % à 9,0 %; 2/78). La prévalence apparente brute des taureaux pour T. foetus était < 0,001 % (IC 95 % : 0,0 % à 0,5 %; 0/735) et la prévalence pour les troupeaux était < 0,001 % (IC 95 % 0,0 % à 4,6 %; 0/78). Les vaches provenant de troupeaux où au moins un taureau s'était avéré positif pour Cfv étaient 2,35 fois plus susceptibles (IC 95 % : 1,01 à 5,48; P = 0,047) de ne pas être gestante que celles provenant de troupeaux sans aucun taureau positif. L'analyse par réaction d'amplification en chaine par la polymérase de matériel prépucial prélevé dans de la saline tamponnée était recommandée pour vérifier la présence de T. foetus lorsque la probabilité d'infection pré-test était > 1 %. Le même type d'analyse pour Cfv n'était pas recommandé pour la vérification des troupeaux à risque modéré et faible étant donné le risque élevé de faux positifs. Les tests pour T. foetus et Cfv peuvent être utilisés pour investiguer les troupeaux avec des problèmes de reproduction en même temps que les autres facteurs de risque sont éliminés. Toutefois, indépendamment du type de test utilisé trois tests négatifs sont requis pour éliminer la possibilité de l'infection dans les situations à risque élevé.(Traduit par Docteur Serge Messier).

Introduced and Native Haplotypes of Echinococcus multilocularis in Wildlife in Saskatchewan, Canada.

Recent detection of a European-type haplotype of the cestode Echinococcus multilocularis in a newly enzootic region in British Columbia prompted efforts to determine if this haplotype was present elsewhere in wildlife in western Canada. In coyote (Canis latrans) definitive hosts in an urban region in central Saskatchewan (SK), we found a single haplotype of E. multilocularis that was most similar to a haplotype currently established in the core of this parasite's distribution in Europe and to the European-type haplotype found in coyotes and a dog (Canis lupus familiaris) in British Columbia. We found six haplotypes of E. multilocularis from deer mouse (Peromyscus maniculatus) intermediate hosts in southwestern SK that were closely related to, and one haplotype indistinguishable from, a haplotype previously reported in the adjacent north-central US. This is a higher level of diversity than has previously been recognized for this parasite, which suggests that the population native to central North America is well established, rather than a recent introduction from the Arctic. These findings, in combination with recent cases of alveolar hydatid cysts in dogs in Canada, raise concerns that European haplotypes of E. multilocularis may be increasing in distribution within wildlife in Canada. European haplotypes may pose greater risks to veterinary and human health than native haplotypes long established in central North America.

Unexpected diversity of the cestode Echinococcus multilocularis in wildlife in Canada.

Echinococcus multilocularis is a zoonotic cestode with a distribution encompassing the northern hemisphere that causes alveolar hydatid disease in people and other aberrant hosts. E. multilocularis is not genetically uniform across its distribution, which may have implications for zoonotic transmission and pathogenicity. Recent findings of a European-type haplotype of E. multilocularis in wildlife in one location in western Canada motivated a broader survey of the diversity of this parasite in wildlife from northern and western Canada. We obtained intact adult cestodes of E. multilocularis from the intestines of 41 wild canids (wolf - Canis lupus, coyote - Canis latrans, and red fox - Vulpes vulpes), taeniid eggs from 28 fecal samples from Arctic fox (Vulpes lagopus), and alveolar hydatid cysts from 39 potential rodent intermediate hosts. Upon sequencing a 370-nucelotide region of the NADH dehydrogenase subunit 1 (nad1) mitochondrial locus, 17 new haplotypes were identified. This constitutes a much higher diversity than expected, as only two genotypes (European and an Asian/North American) had previously been identified using this locus. The European-type strain, recently introduced, may be widespread in wildlife within western Canada, possibly related to the large home ranges and wide dispersal range of wild canids. This study increased understanding of the biogeographic distribution, prevalence and genetic differences of a globally important pathogenic cestode in northern and western Canada.

Echinococcus multilocularis and Echinococcus canadensis in wolves from western Canada.

Echinococcus species are important parasites of wildlife, domestic animals and people worldwide; however, little is known about the prevalence, intensity and genetic diversity of Echinococcus tapeworms in Canadian wildlife. Echinococcus tapeworms were harvested from the intestines of 42% of 93 wolves (Canis lupus) from five sampling regions in the Northwest Territories, Manitoba and Saskatchewan, and visually identified to genus level by microscopic examination. Genetic characterization was successful for tapeworms from 30 wolves, and identified both Echinococcus canadensis and Echinococcus multilocularis in all sampling locations. Mixed infections of E. canadensis/E. multilocularis, as well as the G8/G10 genotypes of E. canadensis were observed. These findings suggest that wolves may be an important definitive host for both parasite species in western Canada. This represents the first report of wolves naturally infected with E. multilocularis in North America, and of wolves harbouring mixed infections with multiple species and genotypes of Echinococcus. These observations provide important information regarding the distribution and diversity of zoonotic species of Echinococcus in western North America, and may be of interest from public health and wildlife conservation perspectives.

Tradition and transition: parasitic zoonoses of people and animals in Alaska, northern Canada, and Greenland.

Zoonotic parasites are important causes of endemic and emerging human disease in northern North America and Greenland (the North), where prevalence of some parasites is higher than in the general North American population. The North today is in transition, facing increased resource extraction, globalisation of trade and travel, and rapid and accelerating environmental change. This comprehensive review addresses the diversity, distribution, ecology, epidemiology, and significance of nine zoonotic parasites in animal and human populations in the North. Based on a qualitative risk assessment with criteria heavily weighted for human health, these zoonotic parasites are ranked, in the order of decreasing importance, as follows: Echinococcus multilocularis, Toxoplasma gondii, Trichinella and Giardia, Echinococcus granulosus/canadensis and Cryptosporidium, Toxocara, anisakid nematodes, and diphyllobothriid cestodes. Recent and future trends in the importance of these parasites for human health in the North are explored. For example, the incidence of human exposure to endemic helminth zoonoses (e.g. Diphyllobothrium, Trichinella, and Echinococcus) appears to be declining, while water-borne protozoans such as Giardia, Cryptosporidium, and Toxoplasma may be emerging causes of human disease in a warming North. Parasites that undergo temperature-dependent development in the environment (such as Toxoplasma, ascarid and anisakid nematodes, and diphyllobothriid cestodes) will likely undergo accelerated development in endemic areas and temperate-adapted strains/species will move north, resulting in faunal shifts. Food-borne pathogens (e.g. Trichinella, Toxoplasma, anisakid nematodes, and diphyllobothriid cestodes) may be increasingly important as animal products are exported from the North and tourists, workers, and domestic animals enter the North. Finally, key needs are identified to better assess and mitigate risks associated with zoonotic parasites, including enhanced surveillance in animals and people, detection methods, and delivery and evaluation of veterinary and public health services.

Echinococcus multilocularis in urban coyotes, Alberta, Canada.

Echinococcus multilocularis is a zoonotic parasite in wild canids. We determined its frequency in urban coyotes (Canis latrans) in Alberta, Canada. We detected E. multilocularis in 23 of 91 coyotes in this region. This parasite is a public health concern throughout the Northern Hemisphere, partly because of increased urbanization of wild canids.

Old problems on a new playing field: Helminth zoonoses transmitted among dogs, wildlife, and people in a changing northern climate.

Although surveillance is limited, indigenous residents at latitudes ranging from 53 to 73°N in Canada appear to have a higher occurrence of infection with some zoonotic parasites than the general population. Conversely, they are relatively naïve to other zoonotic parasites that have previously been unable to establish at northern latitudes. For those parasites that circulate among dogs, wildlife, and people, potential risk factors in the North include limited availability of veterinary services, presence of free-roaming dog populations, and consumption of locally harvested fish and wildlife. These regions are also experiencing some of the greatest impacts of climate change in North America, including increased temperature, precipitation, and frequency and severity of extreme weather. We review the current taxonomy, genetic diversity, host and geographic distributions, epidemiology and risk factors for 3 genera of helminths (Diphyllobothrium spp., Echinococcus spp., and Toxocara sp.) in Canada's North in order to identify climate-sensitive aspects of their ecology. Free-living stages of parasitic zoonoses endemic in the Arctic (such as Diphyllobothrium dendriticum, the cervid strain of Echinococcus granulosus, and Arctic strains of Echinococcus multilocularis) will experience trade-offs between enhanced survival under wetter conditions and increased mortality under warmer conditions. Climate change might also lead to the introduction and establishment in the Arctic of parasitic zoonoses previously restricted to the sub-Arctic, such as Diphyllobothrium latum, Toxocara canis, and the prairie strain of E. multilocularis. Molecular techniques applied in broad geographic surveys are needed to address critical knowledge gaps in the geographic distribution, genetic diversity, and public health significance of zoonotic helminths already in the circumpolar North, and to determine the current barriers to range expansion of temperate-adapted parasites into the North. Dogs will continue to play important roles in the North, including that of a "bridging" host between sylvatic cycles and human communities. In a warming north, increased opportunities for business, agriculture, and tourism favor importation of dogs and their parasites into a newly suitable environment. Collaborations among veterinarians, public health personnel, and policy-makers are needed to enhance surveillance and mitigate for dog-transmitted parasitic zoonoses in a changing North.