TRANSMISSION DYNAMICS OF TOXOPLASMA GONDII IN TERRESTRIAL ECOSYSTEMS OF THE CANADIAN WESTERN ARCTIC

Toxoplasma gondii is a single-celled parasite infecting a wide range of birds and mammals worldwide. In these warm-blooded animals, it usually causes no symptoms but can cause neurological, ocular, and reproductive problems, especially if the immune system is compromised or if a mammal becomes infected while pregnant. Seroprevalence in some Inuit communities is much higher than in other parts of North America. Inuit are thought to be exposed through handling and consumption of Arctic wildlife. As T. gondii are known to produce oocysts in the intestines of felids, and wild and domestic felids are rare in the tundra regions of the Arctic, there are other transmission mechanisms occurring. Previous work has demonstrated that migratory birds are a potential source for introduction of toxoplasmosis, and that Arctic foxes are likely infected through carnivory. The aim of this research was, first, to determine major routes of transmission of T. gondii in a terrestrial Arctic ecosystem at Karrak Lake in the Queen Maud Gulf Bird Sanctuary, Nunavut, in Arctic foxes and Arctic-nesting geese. We also compared molecular and serological techniques used to detect and characterize T. gondii. Finally, reindeer were experimentally infected to determine effects and tissue distribution of the parasite. This work will address important food safety and public health aspects by looking for T. gondii in two key species, geese and caribou, which are important food sources in northern communities. Caribou populations are declining throughout the Arctic. Knowing what effects this parasite can have on caribou gives us information on whether it causes health problems or not. As for Arctic foxes, looking into seroprevalence and mode of transmission will help us understand how this parasite persists in this particular ecosystem. We hypothesize that T. gondii is maintained via vertical transmission (i.e., female foxes to the pups), in addition to transmission by carnivory. To test this hypothesis, and to determine if any changes in serostatus occurred throughout multiple years, we collected and tested blood samples from live-trapped adult and juvenile Arctic foxes. Samples were analyzed in laboratories by serological methods (Indirect Fluorescent Antibody Test (IFAT), Modified Agglutination Test (MAT)) developed and improved previously. We also tested wild goose samples serologically, using filter papers, thoracic fluids and fluids from frozen hearts, and via 2 different methods of DNA extraction followed by PCR for a 529 bp repeating segment. The magnetic capture technique allowed use of up to 100g of tissues compared to ≤25mg with traditional DNA extraction methods, thus increasing the chance to find true positives in heart and brain samples. Finally, we investigated the pathology and tissue distribution of T. gondii in experimentally infected reindeer to determine which tissues pose the greatest risk for human exposure. Our work suggests that T. gondii is present in newborn Arctic foxes, supporting the hypothesis of vertical transmission. We also proposed that subsequent litters can be infected congenitally, not just litters of females infected for the first time in pregnancy, which are pregnant females without T. gondii antibodies at the moment of infection. This can have important implications regarding reproductive success. Changes in serostatus in adult Arctic foxes throughout the years were also noticed, with a higher rate of exposure and seroconversion in mature foxes, as well as a shift of serostatus from positive to negative in an older fox. These findings give us a better understanding of how the parasite can be transmitted and maintained in a terrestrial Arctic ecosystem. Magnetic capture succeeded in detecting higher levels of T. gondii in reindeer tissues than traditional DNA extraction, suggesting the use of this technique when large amount of tissues are available. Toxoplasma gondii was not detected in wild goose tissues (i.e., brain, heart) following conventional PCR and sequencing, possibly due to low infection rates in Ross’s and Lesser Snow Geese, and low sensitivity of the conventional PCR. Antibodies against T. gondii were found serologically in both goose species using body fluids, but not following a chloroform clean-up centrifugation on the samples used to remove fat particles. The quality of samples at the time of serological testing as well as the type of samples (body fluids instead of serum) could explain the negative results after using the chloroform centrifugation. We successfully performed MAT for the first time in the field, suggesting that the use of this technique in remote field areas and northern communities is feasible. Finally, T. gondii was successfully detected in commonly consumed muscles of experimentally infected reindeer. This result gives us important insight on a potential mechanism for food-borne transmission of T. gondii in northern communities and raises concern regarding the safety of caribou meat in naturally infected animals. Subtle behavioral changes were observed in reindeer after infection, as well as respiratory problems in one animal. Numerous studies have demonstrated that T. gondii is capable of vertical transmission in a variety of hosts, including humans. High prevalences of the parasite in host populations that are geographically isolated from definitive felid hosts, as is the case in arctic fox populations, are intriguing scenarios to explore the importance of vertical transmission. It may also help to explain the extent of genetic diversity and the relative roles of sexual recombination (oocysts) vs clonal propagation (asexual reproduction). Moreover, using seroprevalence studies, Arctic foxes can be used as sentinels for T. gondii in this specific ecosystem. This research will provide information about how Arctic peoples become exposed through important food sources (i.e., geese and caribou) and the health effects of toxoplasmosis in threatened wildlife. We need more information on the significance of food-borne routes of transmission of T. gondii in the North in order to implement culturally appropriate and effective local prevention measures

Foxes and Lynx as Sentinels for Toxoplasma gondii across the Canadian North

Toxoplasma gondii is one of the most successful parasites in the world and can have serious adverse effects on immunocompromised individuals and foetuses. It is thus a parasite of public health concern, especially in the Canadian North where seroprevalence in some Inuit communities is much higher than in other parts of North America. Food-borne transmission is likely a significant route of transmission among northern residents as well as Arctic carnivores, where transmission may be altered by the rapid demographic and environmental changes affecting Arctic and subarctic regions. I focused on lynx as the only definitive host that can produce oocysts in subarctic regions, and foxes as intermediate hosts at high risk of exposure. The aim of this research was first to assess T. gondii exposure, prevalence and genetic diversity in foxes and lynx in northern Canada. I hypothesized that foxes would act as good sentinel species for T. gondii in the North since they occupy a high trophic position in the Arctic and are widespread in northern Canada. I also sought to determine if lynx are serving as definitive hosts for T. gondii using DNA based methods (real time PCR with melting-curve analysis) which are more sensitive than efforts to detect oocysts in feces. I used a sequence specific magnetic capture DNA extraction and real-time PCR to test whole hearts and brains of foxes and lynx. I tested samples serologically by enzyme-linked immunosorbent assay (ELISA) using fluids from thawed hearts. I targeted foxes from all four Inuit regions of Canada: Inuvialuit Settlement Region in Canada’s Western Arctic, Nunavut, Nunavik in northern Québec, and Nunatsiavut in Labrador. Exposure and tissue infection were lower in fox and lynx in Canada’s Western Arctic, and higher in the Eastern Arctic, especially the Hudson Bay region of Nunavik. These results are compatible with recent serological findings in people from Inuit Health Surveys, supporting the hypothesis that fox are indeed suitable sentinels of environmental transmission and human exposure to T. gondii. DNA consistent with that of T. gondii was detected in feces of one lynx from boreal regions of Québec, but was detected far more commonly in lynx tissues. While lynx are a potential source of oocysts, they may also contribute to transmission of this parasite through consumption of their tissues by other carnivores and harvesters. This supports my hypothesis that fox are primarily exposed to T. gondii through carnivory rather than consumption of oocysts produced locally by lynx. In order to determine the role prey species play in T. gondii prevalence, I used stable isotopes on muscle and hair of Nunavik foxes to reconstitute their diet and link diet with their infection status. I concluded that marine food sources and migratory birds are likely a major source of exposure in foxes to T. gondii in Nunavik, again similar to recent findings on consumption trends in people in Nunavik. This work reveals a better understanding of the distribution and introduction of T. gondii in fragile Arctic ecosystems. Ultimately, these findings inform future risk assessments to determine the potential human and animal health risks associated with T. gondii in northern ecosystems

TRANSMISSION DYNAMICS OF TOXOPLASMA GONDII IN ARCTIC FOXES (VULPES LAGOPUS): A LONG-TERM MARK-RECAPTURE SEROLOGIC STUDY AT KARRAK LAKE, NUNAVUT, CANADA

Transmission dynamics of Toxoplasma gondii, a parasite of importance for wildlife and human health, are enigmatic in the Arctic tundra, where free-ranging wild and domestic felid definitive hosts are absent and rarely observed, respectively. Through a multiyear mark-recapture study (2011– 17), serosurveillance was conducted to investigate transmission of T. gondii in Arctic foxes (Vulpes lagopus) in the Karrak Lake region, Nunavut, Canada. Sera from adult foxes and fox pups were tested for antibodies to T. gondii by using serologic methods, including the indirect fluorescent antibody test, direct agglutination test, and modified agglutination test. The overall seroprevalence was 39% in adults and 17% in pups. Mature foxes were more likely to be exposed (seroconvert) than young foxes (less than 1 yr old), with the highest level of seroprevalence in midaged foxes (2–4 yr old). Pups in two different litters were seropositive on emergence from the den, around 5 wk old, which could have been due to passive transfer of maternal antibody or vertical transmission of T. gondii from mother to offspring. The seropositive pups were born of seropositive mothers that were also seropositive the year before they gave birth, suggesting that vertical transmission might not be limited to litters from mothers exposed to T. gondii for the first time in pregnancy. All recaptured seropositive foxes remained seropositive on subsequent captures, suggesting that antibodies persist or foxes are constantly reexposed or a combination of both. The results of this study provided insights into how foxes were likely exposed to T. gondii, the dynamics of antibody persistence and immune response, and how the parasite was maintained in a terrestrial Arctic ecosystem in the absence of felid definitive hosts

Les| pratiques de socialisation dans les firmes entrepreneuriales et conservatrices

International audienceLa socialisation organisationnelle est définie comme le processus qui conduit un individu à acquérir les croyances, les valeurs, les comportements et les compétences nécessaires pour exercer pleinement son rôle dans une organisation (Fisher, 1986 ; Van Maanen, 1976). Cet article explore les relations entre la socialisation organisationnelle des nouvelles recrues et l’orientation entrepreneuriale. Plus précisément, il s’agit de comprendre quelles pratiques de socialisation soutiennent l’orientation entrepreneuriale des organisations. Quatre études de cas décrivant les pratiques de socialisation de PME appartenant à différents secteurs d’activité et caractérisées par une forte, ou par une faible orientation entrepreneuriale sont mobilisées pour vérifier le bien-fondé de propositions théoriques reliant orientation entrepreneuriale et pratiques de socialisation des nouvelles recrues.<br/

Les| pratiques de socialisation dans les firmes entrepreneuriales et conservatrices

International audienceLa socialisation organisationnelle est définie comme le processus qui conduit un individu à acquérir les croyances, les valeurs, les comportements et les compétences nécessaires pour exercer pleinement son rôle dans une organisation (Fisher, 1986 ; Van Maanen, 1976). Cet article explore les relations entre la socialisation organisationnelle des nouvelles recrues et l’orientation entrepreneuriale. Plus précisément, il s’agit de comprendre quelles pratiques de socialisation soutiennent l’orientation entrepreneuriale des organisations. Quatre études de cas décrivant les pratiques de socialisation de PME appartenant à différents secteurs d’activité et caractérisées par une forte, ou par une faible orientation entrepreneuriale sont mobilisées pour vérifier le bien-fondé de propositions théoriques reliant orientation entrepreneuriale et pratiques de socialisation des nouvelles recrues.<br/

La socialisation des nouvelles recrues : antécédent caché de l'orientation entrepreneuriale ?

International audienceOrganizational socialization can be defined as a process that leads an individual to acquire the beliefs, values, behaviors, orientations, skills, necessary to fully exercise its role and function in an organization (Fisher, 1986, Van Maanen , 1976). Our article explores the relationship between this neglected facet of human resource management and entrepreneurial orientation. Four case studies describing the socialization practices of SMEs characterized by either a strong or a weak entrepreneurial orientation are mobilized to verify the validity of a set of theoretical propositions linking entrepreneurial orientation and socialization practices.La socialisation organisationnelle peut être définie comme un processus qui conduit un individu à acquérir les croyances, les valeurs, les comportements, les orientations, les compétences, nécessaires pour exercer pleinement son rôle et sa fonction dans l'organisation (Fisher, 1986 ; Van Maanen, 1976).Notre article explore les relations entre cette facette négligée du management des ressources humaines et l'orientation entrepreneuriale. Quatre études de cas décrivant les pratiques de socialisation de PME appartenant à différents secteurs d'activité et caractérisées soit par une forte, soit par une faible orientation entrepreneuriale sont mobilisées pour vérifier le bien fondé d'un ensemble de propositions théoriques reliant orientation entrepreneuriale et pratiques de socialisation. Mots clés : socialisation organisationnelle, orientation entrepreneuriale, antécédents, innovation, étude de cas multiple

Les| pratiques de socialisation dans les firmes entrepreneuriales et conservatrices

International audienceLa socialisation organisationnelle est définie comme le processus qui conduit un individu à acquérir les croyances, les valeurs, les comportements et les compétences nécessaires pour exercer pleinement son rôle dans une organisation (Fisher, 1986 ; Van Maanen, 1976). Cet article explore les relations entre la socialisation organisationnelle des nouvelles recrues et l’orientation entrepreneuriale. Plus précisément, il s’agit de comprendre quelles pratiques de socialisation soutiennent l’orientation entrepreneuriale des organisations. Quatre études de cas décrivant les pratiques de socialisation de PME appartenant à différents secteurs d’activité et caractérisées par une forte, ou par une faible orientation entrepreneuriale sont mobilisées pour vérifier le bien-fondé de propositions théoriques reliant orientation entrepreneuriale et pratiques de socialisation des nouvelles recrues.<br/

Professionnel•les et intermédiaires du droit face aux parents LGBTQ+

La recherche restituée dans ce rapport vise à mieux comprendre les pratiques des professionnel·les et des intermédiaires du droit envers les parents LGBTQ+, ainsi que leurs représentations des droits des personnes issues de la diversité sexuelle et de genre. Dans une perspective de sciences sociales du droit, elle contribue à l’avancée des connaissances sur les dynamiques contemporaines d’inclusion des personnes LGBTQ+, et propose des pistes d’action pour l’actualisation du Plan d’action gouvernemental de lutte contre l’homophobie et la transphobie (2017-2022)

Professionnel•les et intermédiaires du droit face aux parents LGBTQ+

La recherche restituée dans ce rapport vise à mieux comprendre les pratiques des professionnel·les et des intermédiaires du droit envers les parents LGBTQ+, ainsi que leurs représentations des droits des personnes issues de la diversité sexuelle et de genre. Dans une perspective de sciences sociales du droit, elle contribue à l’avancée des connaissances sur les dynamiques contemporaines d’inclusion des personnes LGBTQ+, et propose des pistes d’action pour l’actualisation du Plan d’action gouvernemental de lutte contre l’homophobie et la transphobie (2017-2022)

TRANSMISSION DYNAMICS OF TOXOPLASMA GONDII IN ARCTIC FOXES (VULPES LAGOPUS): A LONG-TERM MARK-RECAPTURE SEROLOGIC STUDY AT KARRAK LAKE, NUNAVUT, CANADA

Transmission dynamics of Toxoplasma gondii, a parasite of importance for wildlife and human health, are enigmatic in the Arctic tundra, where free-ranging wild and domestic felid definitive hosts are absent and rarely observed, respectively. Through a multiyear mark-recapture study (2011– 17), serosurveillance was conducted to investigate transmission of T. gondii in Arctic foxes (Vulpes lagopus) in the Karrak Lake region, Nunavut, Canada. Sera from adult foxes and fox pups were tested for antibodies to T. gondii by using serologic methods, including the indirect fluorescent antibody test, direct agglutination test, and modified agglutination test. The overall seroprevalence was 39% in adults and 17% in pups. Mature foxes were more likely to be exposed (seroconvert) than young foxes (less than 1 yr old), with the highest level of seroprevalence in midaged foxes (2–4 yr old). Pups in two different litters were seropositive on emergence from the den, around 5 wk old, which could have been due to passive transfer of maternal antibody or vertical transmission of T. gondii from mother to offspring. The seropositive pups were born of seropositive mothers that were also seropositive the year before they gave birth, suggesting that vertical transmission might not be limited to litters from mothers exposed to T. gondii for the first time in pregnancy. All recaptured seropositive foxes remained seropositive on subsequent captures, suggesting that antibodies persist or foxes are constantly reexposed or a combination of both. The results of this study provided insights into how foxes were likely exposed to T. gondii, the dynamics of antibody persistence and immune response, and how the parasite was maintained in a terrestrial Arctic ecosystem in the absence of felid definitive hosts