Epidemiological study of Coxiella burnetii in dairy cattle and small ruminants in Québec, Canada.

The bacterium Coxiella burnetii (C. burnetii) can infect a wide range of animals, most notably ruminants where it causes mainly asymptomatic infections and, when clinical, it is associated with reproductive disorders such as abortion. It is also the etiological agent of Q fever in humans, a zoonosis of increasingly important public health concern. A cross-sectional study was performed to estimate the apparent prevalence and spatial distribution of C. burnetii positivity in dairy cattle and small ruminant herds of two regions of Québec, Canada, and identify potential risk factors associated with positivity at animal and herd levels. In dairy cattle herds, individual fecal samples and repeated bulk tank milk samples (BTM) were collected. In small ruminant herds, serum and feces were sampled in individual animals. ELISA analyses were performed on serum and BTM samples. Real-time quantitative PCR (qPCR) was done on fecal and BTM samples. An animal was considered C. burnetii-positive when at least one sample was revealed positive by ELISA and/or qPCR, while a herd was considered C. burnetii-positive when at least one animal inside that herd was revealed positive. None of the 155 cows had a qPCR-positive fecal sample, whereas 37.2 % (95 % CI = 25.3-49.1) of the 341 sheep and 49.2 % (95 % CI = 25.6-72.7) of the 75 goats were C. burnetii-positive. The apparent prevalence of C. burnetii-positive herds was 47.3 % (95 % CI = 35.6-59.3) in dairy cattle herds (n = 74), 69.6 % (95 % CI = 47.1-86.8) in sheep flocks (n = 23) and 66.7 % (95 % CI = 22.3-95.7) in goat herds (n = 6). No spatial cluster of positive herds was detected. At the individual level, the only significant association with positivity in multivariable regressions was higher parity number in small ruminants. At the herd level, the use of calving group pen, the distance to the closest positive bovine herd, and small ruminant herd density in a 5 km radius were associated with dairy cattle herd positivity, whereas small ruminant herds with more than 100 animals and with a dog on the farm had greater odds of C. burnetii positivity. Our study shows that the infection is frequent on dairy cattle and small ruminant herds from the two studied regions and that some farm and animal characteristics might influence the transmission dynamics of the C. burnetii infection.

Ecology of Arctic rabies: 60 years of disease surveillance in the warming climate of northern Canada.

Rabies occurs throughout the Arctic, representing an ongoing public health concern for residents of northern communities. The Arctic fox (Vulpes lagopus) is the main reservoir of the Arctic rabies virus variant, yet little is known about the epidemiology of Arctic rabies, such as the ecological mechanisms driving where and when epizootics in fox populations occur. In this study, we provide the first portrait of the spatio-temporal spread of rabies across northern Canada. We also explore the impact of seasonal and multiannual dynamics in Arctic fox populations and climatic factors on rabies transmission dynamics. We analysed data on rabies cases collected through passive surveillance systems in the Yukon, Northwest Territories, Nunavut, Nunavik and Labrador from 1953 to 2014. In addition, we analysed a large and unique database of trapped foxes tested for rabies in the Northwest Territories and Nunavut from 1974 to 1984 as part of active surveillance studies. Rabies cases occurred in all Arctic regions of Canada and were relatively synchronous among foxes and dogs (Canis familiaris). This study highlights the spread of Arctic rabies virus variant across northern Canada, with contrasting rabies dynamics between different yet connected areas. Population fluctuations of Arctic fox populations could drive rabies transmission dynamics in a complex way across northern Canada. Furthermore, this study suggests different impacts of climate and sea ice cover on the onset of rabies epizootics in northern Canada. These results lay the groundwork for the development of epidemiological models to better predict the spatio-temporal dynamics of rabies occurrence in both wild and domestic carnivores, leading to better estimates of human exposure and transmission risk.

High-throughput identification and quantification of Haemonchus contortus in fecal samples.

Haemonchus contortus are gastrointestinal nematodes of the family Trichostrongylidae that naturally infect small ruminants while grazing, posing a risk to both animal health and farm profitability. Current diagnostics depend on exacting lab techniques, including manual egg counts and larval differentiation, all of which require time, effort, and specialized technicians. The goal of this study was to facilitate and accelerate the identification and quantification of H. contortus in fecal samples through the use of fluorescein-isothiocyanate peanut-agglutinin staining in order to allow automated detection using a 96-well microplate reader. Next, the model was to be validated using samples containing unknown quantities of eggs. Automated analysis of fluorescence emission of known quantities of H. contortus eggs confirmed an almost perfect linear correlation (r = 0.9984, p < 0.0001), indicating that this new approach can satisfactorily be used to quantify H. contortus eggs on a comparative fluorescence scale. As validation, clinical samples containing an unknown quantity of H. contortus eggs were then analyzed by comparing two methods: either Wisconsin Sugar Flotation (WSF) and McMaster counting followed by manual fluorescence microscopy, or WSF coupled with automated microplate reading. Pearson analysis revealed highly significant correlation between manual and automated methods (r = 0.9999, p < 0.0001), while Bland-Altman plots demonstrated excellent agreement between the two (bias = -0.817 ± 9.94 with 95% limits of agreement from -20.31 to 18.67). Overall, these results demonstrate that high-throughput screening fluorescence detection and quantification of H. contortus eggs is both accurate and rapid.

Acceptability of tick control interventions to prevent Lyme disease in Switzerland and Canada: a mixed-method study.

BACKGROUND: Lyme disease control strategies may include tick control interventions in high risk areas. Public authorities may be interested to assess how these types of interventions are perceived by the public which may then impact their acceptability. The aims of this paper are to compare socio-cognitive factors associated with high acceptability of tick control interventions and to describe perceived issues that may explain their low acceptability in populations living in two different regions, one being an endemic region for LD since the last 30 years, the Neuchâtel canton, in Switzerland, and another where the disease is emerging, the Montérégie region, in Canada. METHODS: A mixed methods' design was chosen. Quantitative data were collected using web-surveys conducted in both regions (n = 814). Multivariable logistic regressions were used to compare socio-cognitive factors associated with high acceptability of selected interventions. Qualitative data were collected using focus group's discussions to describe perceived issues relative to these interventions. RESULTS: Levels of acceptability in the studied populations were the lowest for the use of acaricides and landscaping and were under 50 % in both regions for six out of eight interventions, but were higher overall in Montérégie. High perceived efficacy of the intervention was strongly associated with high acceptability of tick control interventions. A high perceived risk about LD was also associated with a high acceptability of intervention under some models. High level of knowledge about LD was negatively associated with high acceptability of the use of acaricides in Neuchâtel. Perceived issues explaining low acceptability included environmental impacts, high costs to the public system, danger of individual disempowerment and perceptions that tick control interventions were disproportionate options for the level of LD risk. CONCLUSION: This study suggests that the perceived efficacy and LD risk perception may be key factors to target to increase the acceptability of tick control interventions. Community-level issues seem to be important considerations driving low acceptability of public health interventions. Results of this study highlight the importance for decision-makers to account for socio-cognitive factors and perceived issues that may affect the acceptability of public health interventions in order to maximize the efficacy of actions to prevent and control LD.

Adaptation and Evaluation of a Multi-Criteria Decision Analysis Model for Lyme Disease Prevention.

Designing preventive programs relevant to vector-borne diseases such as Lyme disease (LD) can be complex given the need to include multiple issues and perspectives into prioritizing public health actions. A multi-criteria decision aid (MCDA) model was previously used to rank interventions for LD prevention in Quebec, Canada, where the disease is emerging. The aim of the current study was to adapt and evaluate the decision model constructed in Quebec under a different epidemiological context, in Switzerland, where LD has been endemic for the last thirty years. The model adaptation was undertaken with a group of Swiss stakeholders using a participatory approach. The PROMETHEE method was used for multi-criteria analysis. Key elements and results of the MCDA model are described and contrasted with the Quebec model. All criteria and most interventions of the MCDA model developed for LD prevention in Quebec were directly transferable to the Swiss context. Four new decision criteria were added, and the list of proposed interventions was modified. Based on the overall group ranking, interventions targeting human populations were prioritized in the Swiss model, with the top ranked action being the implementation of a large communication campaign. The addition of criteria did not significantly alter the intervention rankings, but increased the capacity of the model to discriminate between highest and lowest ranked interventions. The current study suggests that beyond the specificity of the MCDA models developed for Quebec and Switzerland, their general structure captures the fundamental and common issues that characterize the complexity of vector-borne disease prevention. These results should encourage public health organizations to adapt, use and share MCDA models as an effective and functional approach to enable the integration of multiple perspectives and considerations in the prevention and control of complex public health issues such as Lyme disease or other vector-borne and zoonotic diseases.

Factors associated with preventive behaviors regarding Lyme disease in Canada and Switzerland: a comparative study.

BACKGROUND: Lyme disease (LD) is a vector-borne disease that is endemic in many temperate countries, including Switzerland, and is currently emerging in Canada. This study compares the importance of knowledge, exposure and risk perception for the adoption of individual preventive measures, within and between two different populations, one that has been living in a LD endemic region for several decades, the Neuchâtel canton in Switzerland, and another where the disease is currently emerging, the Montérégie region in the province of Québec, Canada. METHODS: A web-based survey was carried out in both study regions (814 respondents) in 2012. Comparative analysis of the levels of adoption of individual preventive measures was performed and multivariable logistic regression analyses were used to test and compare how knowledge, exposure and risk perception were associated with the adoption of selected measures in both regions and globally. RESULTS: In Montérégie, the proportion of reported adoption of five of the most commonly recommended preventive measures varied from 6% for 'applying acaricides on one's property' to 49% for 'wearing protective clothing', and in Neuchâtel, proportions ranged from 6% (acaricides) to 77% for 'checking for ticks (tick check)'. Differences were found within gender, age groups and exposure status in both regions. The perceived efficacy of a given measure was the strongest factor associated with the adoption of three specific preventive behaviors for both regions: tick check, protective clothing and tick repellent. Risk perception and a high level of knowledge about LD were also significantly associated with some of these specific behaviors, but varied by region. CONCLUSIONS: These results strongly suggest that social and contextual factors such as the epidemiological status of a region are important considerations to take into account when designing effective prevention campaigns for Lyme disease. It furthermore underlines the importance for public health authorities to better understand and monitor these factors in targeted populations in order to be able to implement preventive programs that are well adapted to a population and the epidemiological contexts therein.

From Lyme disease emergence to endemicity: a cross sectional comparative study of risk perceptions in different populations.

BACKGROUND: Lyme disease (LD) is a tick-borne emerging disease in Canada that has been endemic in many temperate countries for decades. Currently, one of the main approaches for LD prevention is the promotion of individual-level preventive behaviors against ticks. Health behaviors are influenced by individual and social factors, one important of which is risk perception. This study aims to describe and compare risk perception of LD, within and between general populations and experts living in two different regions: the Neuchâtel canton in Switzerland, where LD is endemic, and the Montérégie region in Québec (Canada), where LD is emerging. METHOD: A web-based survey was conducted in both study regions (814 respondents) in 2012, and a questionnaire was administered to 16 experts. Comparative analyses of knowledge, risk exposure and different components of LD risk perception were performed. Multivariate analyses were used to calculate a global risk perception score and to identify determinants of risk perception in both regions. RESULTS: In Montérégie, only 15% of the survey respondents had a good level of knowledge of LD compared to Neuchâtel where 51% of survey respondents had good levels of knowledge. In Montérégie, 24% of respondents perceived themselves as being at high or very high risk of contracting LD vs 54% in Neuchâtel; however, a higher percentage of respondents from this region believed that personal protection was simple to carry out (73% vs 58% in Montérégie). Based on the population surveys, almost all of the identified determinants of risk perception were different between both populations except for gender. A good level of knowledge, living in the risk zone and knowing someone who has had LD increased risk perception, while a high level of education and being 18-34 years of age decreased this perception. The majority of the studied components of risk perception were different between populations and their regional experts. CONCLUSION: This study suggests that risk perception of LD differs between populations and regional experts living in different epidemiological situations. Monitoring of knowledge and risk perception in local populations may help to better target LD communication efforts in accordance with population specific attributes thereby enhancing prevention efficacy.

Characterizing rabies epidemiology in remote Inuit communities in Québec, Canada: a "One Health" approach.

Rabies is endemic throughout arctic areas including the region of Nunavik, situated north of the 55th parallel of Québec, Canada, and raises public health concerns. The aim of this paper is to provide a descriptive overview of the temporal and regional distributions of three important components of arctic rabies in Nunavik from 1999 to 2012, following a "One Health" approach: animal rabies tests and confirmed cases, dog vaccination, and human consultations for potential rabies exposures. Forty-four cases of rabies, involving mainly arctic and red foxes, were confirmed in animals during this period. The mean number of dogs vaccinated per 1,000 inhabitants was highly variable and lower in the Hudson region than the Ungava region. 112 consultations for potential rabies exposure were analyzed, of which 24 were exposure to a laboratory confirmed rabid animal. Children less than 10 years of age were the age group most commonly exposed. The median time between potential exposure and administration of the first post-exposure prophylaxis dose was four days. This study confirms that the risk of human exposure to rabid animals in Nunavik is present and underlines the need to follow a "One Health" approach to prevent rabies in humans in similar contexts worldwide.

Proportional mortality: A study of 152 goats submitted for necropsy from 13 goat herds in Quebec, with a special focus on caseous lymphadenitis.

The objectives of this study were to determine the main causes of mortality, with a special focus on caseous lymphadenits as a cause of death or wasting in caprine herds from Quebec. Goats (n = 152) from 13 herds were submitted for necropsy; the cause of mortality, and the presence, location, and cause of abscesses (if present) were recorded. Proportional mortalities were distributed as: Clostridium perfringens type D enterotoxemia (17.1%), pneumonia (13.8%), paratuberculosis (10.5%), listeriosis (6.6%), pregnancy toxemia (5.3%), caprine arthritis-encephalitis (4.6%), and caseous lymphadenitis (3.9%). Caseous lymphadenitis was diagnosed in 24.3% of the submitted goats, but was not a major cause of wasting or mortality. Abscesses were localized internally in 54.1% of the cases. Paratuberculosis was diagnosed in 29 goats (16 as cause of death) and was considered a major cause of wasting and/or mortality.

Mortalité proportionnelle: Une étude de 152 chèvres soumises pour nécropsie provenant de 13 élevages caprins du Québec, avec une attention particulière à la lymphadénite caséeuse. Les objectifs de cette étude furent de déterminer les principales causes de mortalité avec une attention particulière à la lymphadénite caséeuse comme cause de mortalité ou de dépérissement chez les chèvres du Québec. Cent-cinquante-deux chèvres provenant de 13 élevages différents ont été soumises pour nécropsie; la cause de mortalité, la présence d'abcès, leur localisation et leur cause (s'il y a lieu) furent compilées. Les mortalités proportionnelles furent distribuées ainsi : entérotoxémie de type D (17,1 %), pneumonie (13,8 %), paratuberculose (10,5 %), listériose (6,6 %), toxémie de gestation (5,3 %), arthrite-encéphalite caprine (4,6 %) et lymphadénite caséeuse (3,9 %). La lymphadénite caséeuse a été diagnostiquée chez 24,3 % des chèvres soumises, mais sans être une cause majeure de dépérissement et de mortalité. Les abcès étaient localisés de façon interne dans 54,1 % des cas. Au total, la paratuberculose a été diagnostiquée chez 29 chèvres (16 en étant décédées) et fut considérée comme une cause majeure de dépérissement et/ou de mortalité.(Traduit par les auteurs).

Multi-criteria decision analysis as an innovative approach to managing zoonoses: results from a study on Lyme disease in Canada.

BACKGROUND: Zoonoses are a growing international threat interacting at the human-animal-environment interface and call for transdisciplinary and multi-sectoral approaches in order to achieve effective disease management. The recent emergence of Lyme disease in Quebec, Canada is a good example of a complex health issue for which the public health sector must find protective interventions. Traditional preventive and control interventions can have important environmental, social and economic impacts and as a result, decision-making requires a systems approach capable of integrating these multiple aspects of interventions. This paper presents the results from a study of a multi-criteria decision analysis (MCDA) approach for the management of Lyme disease in Quebec, Canada. MCDA methods allow a comparison of interventions or alternatives based on multiple criteria. METHODS: MCDA models were developed to assess various prevention and control decision criteria pertinent to a comprehensive management of Lyme disease: a first model was developed for surveillance interventions and a second was developed for control interventions. Multi-criteria analyses were conducted under two epidemiological scenarios: a disease emergence scenario and an epidemic scenario. RESULTS: In general, we observed a good level of agreement between stakeholders. For the surveillance model, the three preferred interventions were: active surveillance of vectors by flagging or dragging, active surveillance of vectors by trapping of small rodents and passive surveillance of vectors of human origin. For the control interventions model, basic preventive communications, human vaccination and small scale landscaping were the three preferred interventions. Scenarios were found to only have a small effect on the group ranking of interventions in the control model. CONCLUSIONS: MCDA was used to structure key decision criteria and capture the complexity of Lyme disease management. This facilitated the identification of gaps in the scientific literature and enabled a clear identification of complementary interventions that could be used to improve the relevance and acceptability of proposed prevention and control strategy. Overall, MCDA presents itself as an interesting systematic approach for public health planning and zoonoses management with a "One Health" perspective.

Does high biodiversity reduce the risk of Lyme disease invasion?

BACKGROUND: It has been suggested that increasing biodiversity, specifically host diversity, reduces pathogen and parasite transmission amongst wildlife (causing a "dilution effect"), whereby transmission amongst efficient reservoir hosts, (e.g. Peromyscus spp. mice for the agent of Lyme disease Borrelia burgdorferi) is reduced by the presence of other less efficient host species. If so, then increasing biodiversity should inhibit pathogen and parasite invasion. METHODS: We investigated this hypothesis by studying invasion of B. burgdorferi and its tick vector Ixodes scapularis in 71 field sites in southeastern Canada. Indices of trapped rodent host diversity, and of biodiversity of the wider community, were investigated as variables explaining the numbers of I. scapularis collected and B. burgdorferi infection in these ticks. A wide range of alternative environmental explanatory variables were also considered. RESULTS: The observation of low I. scapularis abundance and low B. burgdorferi infection prevalence in sites where I. scapularis were detected was consistent with early-stage invasion of the vector. There were significant associations between the abundance of ticks and season, year of study and ambient temperature. Abundance of host-seeking larvae was significantly associated with deer density, and abundance of host-seeking larvae and nymphs were positively associated with litter layer depth. Larval host infestations were lower where the relative proportion of non-Peromyscus spp. was high. Infestations of hosts with nymphs were lower when host species richness was higher, but overall nymphal abundance increased with species richness because Peromyscus spp. mouse abundance and host species richness were positively correlated. Nymphal infestations of hosts were lower where tree species richness was higher. B. burgdorferi infection prevalence in ticks varied significantly with an index of rates of migratory bird-borne vector and pathogen invasion. CONCLUSIONS: I. scapularis abundance and B. burgdorferi prevalence varied with explanatory variables in patterns consistent with the known biology of these species in general, and in the study region in particular. The evidence for a negative effect of host biodiversity on I. scapularis invasion was mixed. However, some evidence suggests that community biodiversity beyond just host diversity may have direct or indirect inhibitory effects on parasite invasion that warrant further study.

Oral rabies vaccination of raccoons and striped skunks with ONRAB® baits: multiple factors influence field immunogenicity.

Multiple control methods have been used in North America to manage the spread of rabies caused by the raccoon (Procyon lotor) rabies virus variant (RRVV). Recently, oral vaccination with ONRAB(®) vaccine baits, which contain an adenovirus rabies glycoprotein recombinant, has been made available as an additional tool for rabies control. Our objectives were to estimate rabies antibody prevalence in wild-caught raccoons and striped skunks (Mephitis mephitis), and identify factors influencing the probability of being antibody positive at the individual level in these species, following oral rabies vaccination (ORV) campaigns in which ONRAB was distributed aerially in 2007-2009 in southern Québec, Canada. Following the aerial distribution of 43-155 ONRAB baits/km(2), the annual percentages of antibody-positive raccoons and skunks varied between 35% and 56% and 11% and 17%, respectively. In raccoons, the probability of being antibody positive was positively associated with age and density of ONRAB distributed, and influenced by the number of previous ORV campaigns conducted. Conversely, this probability was negatively associated with estimated abundance of raccoons in the trapping cell and proportion of residential areas near the raccoon capture location. None of the variables examined explained variation in the probability of being antibody positive in skunks. Our results indicate that the ONRAB density applied during ORV campaigns should be adjusted to account for variations in raccoon population density and presence of residential areas to increase the likelihood of creating an effective immunological barrier against RRVV. The high percentage of juvenile raccoons (annual mean =45 ± 3 [SE]%) and skunks (66 ± 2%) captured during post-ORV monitoring suggests that ORV campaigns should be conducted at least annually to account for the recruitment of naïve individuals into the populations. In Québec, the increasing use of ONRAB coincided with the elimination of rabies caused by RRVV. Nonetheless, our results indicate that improvements to this vaccine bait and/or the distribution techniques are required to increase its efficacy, especially in striped skunks.

From science to action and from action to science: the Nunavik Trichinellosis Prevention Program.

OBJECTIVES: During the 1980s, walrus-meat consumption caused infections with the parasite Trichinella nativa in Nunavik inhabitants. In response to these events, stakeholders set up the community-based Nunavik Trichinellosis Prevention Program (NTPP). The objectives of the present communication are to review the NTPP, describe how science and action were interwoven in its development and identify its assets and limitations. Study design. Descriptive study. METHODS: The NTPP relies on a pooled digestion assay of tongue samples taken from each harvested walrus. The public health recommendations depend on the results of the analyses: infected walrus meat should be destroyed; parasite-free meat may be eaten raw or cooked. RESULTS: All communities involved in the walrus hunt participate in the NTPP and a high percentage of harvested walruses are included in the NTPP. Infected animals account for 2.9% of the walruses tested (20/694) since 1992. The NTPP permitted the early management of a trichinellosis event in 1997. Since then, it prevented the new occurrence of outbreaks related to walruses hunted by Nunavimmiut. CONCLUSIONS: The absence of recent major outbreaks of trichinellosis in Nunavik may reasonably be attributed to the NTPP. The success of the program stands on many facilitating factors such as the nature of the disease and its source, the existence of an efficient analytic method, the strong involvement of the different partners including direct resource users, as well as the comprehensive bidirectional science-to-action approach that has been followed.

Spatially explicit multi-criteria decision analysis for managing vector-borne diseases.

The complex epidemiology of vector-borne diseases creates significant challenges in the design and delivery of prevention and control strategies, especially in light of rapid social and environmental changes. Spatial models for predicting disease risk based on environmental factors such as climate and landscape have been developed for a number of important vector-borne diseases. The resulting risk maps have proven value for highlighting areas for targeting public health programs. However, these methods generally only offer technical information on the spatial distribution of disease risk itself, which may be incomplete for making decisions in a complex situation. In prioritizing surveillance and intervention strategies, decision-makers often also need to consider spatially explicit information on other important dimensions, such as the regional specificity of public acceptance, population vulnerability, resource availability, intervention effectiveness, and land use. There is a need for a unified strategy for supporting public health decision making that integrates available data for assessing spatially explicit disease risk, with other criteria, to implement effective prevention and control strategies. Multi-criteria decision analysis (MCDA) is a decision support tool that allows for the consideration of diverse quantitative and qualitative criteria using both data-driven and qualitative indicators for evaluating alternative strategies with transparency and stakeholder participation. Here we propose a MCDA-based approach to the development of geospatial models and spatially explicit decision support tools for the management of vector-borne diseases. We describe the conceptual framework that MCDA offers as well as technical considerations, approaches to implementation and expected outcomes. We conclude that MCDA is a powerful tool that offers tremendous potential for use in public health decision-making in general and vector-borne disease management in particular.

Advancements in web-database applications for rabies surveillance.

BACKGROUND: Protection of public health from rabies is informed by the analysis of surveillance data from human and animal populations. In Canada, public health, agricultural and wildlife agencies at the provincial and federal level are responsible for rabies disease control, and this has led to multiple agency-specific data repositories. Aggregation of agency-specific data into one database application would enable more comprehensive data analyses and effective communication among participating agencies. In Québec, RageDB was developed to house surveillance data for the raccoon rabies variant, representing the next generation in web-based database applications that provide a key resource for the protection of public health. RESULTS: RageDB incorporates data from, and grants access to, all agencies responsible for the surveillance of raccoon rabies in Québec. Technological advancements of RageDB to rabies surveillance databases include (1) automatic integration of multi-agency data and diagnostic results on a daily basis; (2) a web-based data editing interface that enables authorized users to add, edit and extract data; and (3) an interactive dashboard to help visualize data simply and efficiently, in table, chart, and cartographic formats. Furthermore, RageDB stores data from citizens who voluntarily report sightings of rabies suspect animals. We also discuss how sightings data can indicate public perception to the risk of racoon rabies and thus aid in directing the allocation of disease control resources for protecting public health. CONCLUSIONS: RageDB provides an example in the evolution of spatio-temporal database applications for the storage, analysis and communication of disease surveillance data. The database was fast and inexpensive to develop by using open-source technologies, simple and efficient design strategies, and shared web hosting. The database increases communication among agencies collaborating to protect human health from raccoon rabies. Furthermore, health agencies have real-time access to a wide assortment of data documenting new developments in the raccoon rabies epidemic and this enables a more timely and appropriate response.

Understanding effects of barriers on the spread and control of rabies.

This chapter reviews the evidence for the impact of natural and anthropogenic barriers on the spread of rabies using evidence mainly drawn from the epidemics of fox and raccoon variant rabies virus over the past 60 years in North America. Those barriers have both directed and inhibited the spread of rabies and, at a regional scale, have been integrated with rabies control efforts in North America. Few studies have been done, however, to examine how the texture (grain) and configuration of the habitat at finer scales affect rabies control, particularly the massive oral vaccination campaigns in operation along the Atlantic coast and southeastern Canada (Ontario, Québec, New Brunswick). To explore these questions, the authors used stochastic simulation. The model of choice was the Ontario Rabies Model (ORM) adapted for use on the high performance computing resources network in Québec (RQCHP-Réseau québécois de calcul de haute performance; http://rqchp.qc.ca). The combination of the ORM and RQCHP allowed us to run many thousands of experiments to explore interactions between nine landscape grain/configuration combinations and vaccination barriers with varying widths and immunity levels. Our results show that breaches of vaccine barriers increase as the grain size of the landscape increases and as the landscape becomes more structured. We caution that mid levels of vaccination can be counterproductive resulting in rabies persistence rather than control. We also note that our model/computing system has the flexibility and capacity to explore a wide range of questions pertinent to improving the efficacy of rabies control.

Risk factors associated with West Nile virus mortality in American Crow populations in Southern Quebec.

Soon after the appearance of West Nile virus (WNV) in North America, a number of public health authorities designated the American Crow (Corvus brachyrhynchos) a sentinel for WNV detection. Although preliminary studies have suggested a positive association between American Crow mortality and increased risk of WNV infection in humans, we still know little about dynamic variation in American Crow mortality, both baseline levels and mortality associated with WNV. We hypothesized that the complex social behavior of American Crows, which is shaped by age and seasonal factors, influences both baseline mortality and WNV mortality in American Crow populations. We examined American Crow mortality data from Quebec for the 2005 WNV surveillance year, which lasted from 5 June to 17 September 2005. The variables of interest were age, gender, body condition index, time of year, and land cover. We used a log-linear model to examine baseline mortality. Logistic regression and general linear regression models were constructed to examine variables associated with mortality due to WNV. We found that both age and time of year were key variables in explaining baseline mortality. These two variables were also risk factors for WNV mortality. The probability that a carcass tested positive for WNV increased with the age of the dead bird and as summer progressed. WNV-positive carcasses also had a lower body condition index than WNV-negative carcasses. We believe that the first major wave of American Crow mortality observed in the early summer of 2005 was the result of natural mortality among young American Crows. Because this mortality was not linked to WNV, it appears that American Crow may not be a good species for early detection of WNV activity. Our data also suggest that second-year American Crows play a major role in propagating WNV during their movements to urban land covers during midsummer.

Risk factors and impacts of clinical and subclinical mastitis in commercial meat-producing sheep flocks in Quebec, Canada.

We conducted a prospective observational study on clinical and subclinical mastitis in 30 commercial meat-producing sheep flocks from 2 regions of the province of Quebec, Canada. A total of 2,792 ewes selected in late gestation were followed from lambing to weaning of lambs. The incidence of clinical mastitis for the total lactation period (average of 58 days) ranged among flocks from 0 to 6.6%, with a median of 1.2%. The most frequently isolated bacteria from the cases of clinical mastitis, in pure or mixed culture, were Mannheimia haemolytica (26%), Staphylococcus aureus (23%), and coagulase-negative staphylococci (17%). Incidence of clinical mastitis was higher in ewes that gave birth to 3 or more lambs and from the Estrie region, and was associated with an increase in ewe mortality, an increase in lamb mortality at the litter level, and a decrease in lamb's weaning weight for lambs born in multiple litter size or from ewes >or=4 years old. Among 354 selected ewes with clinically normal udder at the end of lactation, 28.8% had potentially pathogenic bacteria isolated from milk. The most prevalent bacteria were S. aureus (9.3%) and coagulase-negative staphylococci (9.3%). The risk of having a positive culture in at least one half was different between the two regions. Prevalence of ewes (n=261) with California Mastitis Test (CMT) positive result in at least one half was 24.1 and 14.9% using a cut-off of >or=1+ and >or=2+, respectively. Prevalence of culture-positive udder halves was 11.7% for CMT-negative compared with 53.6% for CMT 3+ halves. CMT status was positively associated with the isolation of coagulase-negative staphylococci, M. haemolytica, S. aureus, and various Streptococcus species, but not with other isolated bacteria. Additionally, prevalence of CMT-positive halves was higher in ewes from the Estrie region, aged of >or=4 years versus 1 year, having clinical mastitis previously detected in the lactation and/or with low body condition score. Lamb weaning weight was associated with CMT status of ewes, while weaning weight was not associated with milk culture results. More research is needed to understand the dynamic of milk SCC and IMI in ewes from meat-producing flocks, its economical impact and best ways to control it.

Development of agroenvironmental indicators to evaluate the hygienic pressure of livestock production on human health.

Infections by enteropathogenic microorganisms linked to agroenvironmental contamination represent a significant threat to urban and rural communities. To better characterize and manage this risk, it is necessary, not only to accurately describe enteric illnesses occurring over time or across regions, but also to correctly assess exposure attributable to this environmental pollution. New agroenvironmental hygienic pressure indicators (AHPIs) were developed to synthesise relevant data expressing this exposure. They were derived from a conceptual framework for developing sustainable agriculture indicators and specifically adapted for describing the microbial risk of water contamination by livestock operations. The proposed indicators include two components, and five attributes whose values are calculated at the livestock operation level from a set of available data related to the fields of microbiology, animal production, agronomy, hydrology, and meteorology. They are then aggregated at a higher geographical level to better express exposure of human populations to potential of water contamination by zoonotic enteropathogens. The indicators are calculated separately by zoonotic enteropathogens, and by water source (surface or groundwater). They take into account the various animal species within each livestock operation. When validated, the proposed indicators will allow decision-makers and public health officials to better manage crucial issues in the area of water safety and agriculture.

Lack of evidence of Brucella ovis infection in rams in Quebec.

A study was conducted to estimate the seroprevalence of Brucella ovis infection in rams in the Estrie and Bas-Saint-Laurent regions (Quebec). Rams sera (n = 258) were serologically evaluated from 224 rams in 30 commercial flocks and from 34 rams at 2 slaughterhouses by using an enzyme linked immunosorbent assay. Epididymides and testes were examined by palpation on farms and microscopically for culled rams. No ram was seropositive to Brucella ovis or had lesions suggestive of brucellosis from the farm or slaughterhouse surveys.