Comparison of Machine Learning Tree-Based Algorithms to Predict Future Paratuberculosis ELISA Results Using Repeat Milk Tests.

Machine learning algorithms have been applied to various animal husbandry and veterinary-related problems; however, its use in Johne's disease diagnosis and control is still in its infancy. The following proof-of-concept study explores the application of tree-based (decision trees and random forest) algorithms to analyze repeat milk testing data from 1197 Canadian dairy cows and the algorithms' ability to predict future Johne's test results. The random forest models using milk component testing results alongside past Johne's results demonstrated a good predictive performance for a future Johne's ELISA result with a dichotomous outcome (positive vs. negative). The final random forest model yielded a kappa of 0.626, a roc AUC of 0.915, a sensitivity of 72%, and a specificity of 98%. The positive predictive and negative predictive values were 0.81 and 0.97, respectively. The decision tree models provided an interpretable alternative to the random forest algorithms with a slight decrease in model sensitivity. The results of this research suggest a promising avenue for future targeted Johne's testing schemes. Further research is needed to validate these techniques in real-world settings and explore their incorporation in prevention and control programs.

Infestation patterns of Ixodes scapularis and Dermacentor variabilis on dogs and cats across Canada.

Due to recent climatic and land use changes, Canada has experienced changes in tick populations, leading to an increased risk of tick bites and tick-borne pathogen exposure, especially in eastern Canada. Preventative recommendations for companion animals from veterinary professionals include regular use of tick prevention products and tick checks. Tick checks, specifically, should target regions of an animal's body which are deemed to be high risk for tick attachment. However, tick species-specific infestation patterns on dogs and cats are largely understudied, and additional research is needed to help guide targeted tick checks. The objective of this study was to identify tick species-specific infestation patterns on dogs and cats. Ticks were collected for one year (April 2019 -March 2020) from 94 veterinary clinics across Canada as part of the Canadian Pet Tick Survey. All ticks were identified to species, and data on the location of tick attachment were ascertained with each submission. To examine the association between location of attachment (outcome) and tick species (explanatory variable), specifically Ixodes scapularis and Dermacentor variabilis, mixed effects univariable models were built. Two thousand three hundred and six submissions were received from 1925 dogs and 381 cats across Canada. Of these submissions, 1377 comprised Ixodes scapularis, and 620 comprised Dermacentor variabilis. Clear tick species-specific infestation patterns for dogs were present, with I. scapularis being significantly more likely to be found on the shoulders, and D. variabilis more likely to be found on the ears and neck. Dermacentor variabilis was more likely to be found on the cranial aspect of cats' limbs, compared to I. scapularis. Up-to-date information on infestation patterns can be used to inform veterinary professionals and pet owners of common attachment sites based on established ticks in their region and thus conduct targeted tick checks.

Assessing the spatial and temporal patterns and risk factors for acquisition of Ixodes spp. by companion animals across Canada.

Climatic and land use changes have contributed to substantial changes in the abundance, distribution, and activity patterns of ticks in Canada, which have led to an increased risk of tick bites and tick-borne pathogen exposure for companion animals. The objectives of this study were to describe current spatial and temporal patterns of Ixodes spp. on companion animals in Canada and explore the association between tick bites and dog and cat demographic factors. Ticks were collected for one year (April 2019 - March 2020) from 94 veterinary clinics. Included with each submission was a short questionnaire containing owner-reported information on travel history, date of removal and suspected location of tick acquisition, and animal-specific demographic factors. Ticks were identified morphologically using a stereomicroscope, standard keys, and through PCR analyses. Mixed effect multivariable logistic regression models were built to explore the association between an Ixodes scapularis bite and animal demographic factors; veterinary clinic was included as a random effect. Approximately 2300 submissions were received from clinics across Canada, totalling 4425 ticks. The most common Ixodes spp. was I. scapularis (n = 2168), followed by Ixodes pacificus (n = 172) and Ixodes cookei (n = 155). Ixodes scapularis were well distributed in regions across central and eastern Canada. Ixodes cookei was found in eastern Canada, with the greatest numbers from Quebec and New Brunswick. Ixodes pacificus submissions were restricted to British Columbia. Across eastern Canada, dogs of the herding, mixed breed (large and small), sporting, working, terrier, and toy breed groups, and spayed cats were all found to have higher odds of acquiring I. scapularis, compared to other tick species. For the dog model, significant interactions were found between predictor variables age and sex. Regional information on tick distribution, seasonality, and risk factors for acquisition contribute to evidence-based veterinary practices for tick and tick-borne disease control in Canada.

Molecular identification of Cryptosporidium species in Canadian post-weaned calves and adult dairy cattle.

Cryptosporidium is a zoonotic protozoan parasite that is distributed globally and impacts both human and animal health. There are over 40 species of Cryptosporidium described to date, of which four (C. parvum, C. bovis, C. ryanae and C. andersoni) are routinely reported in cattle. The goal of this study was to identify the Cryptosporidium species infecting dairy cattle from across Canada using cow fecal samples and post-weaned calf rectal swabs obtained through the Canadian National Dairy Study. A total of 353 cattle samples (117 pooled rectal fecal swabs from post-weaned calves and 236 cow fecal samples) from 175 herds across the 10 Canadian provinces were analysed by targeting Cryptosporidium's small subunit ribosomal RNA (SSU rRNA or 18S) gene. Herd prevalence of Cryptosporidium was 27.4% nationally, ranging from 0% in Saskatchewan (SK) to 62% in Prince Edward Island (PE). The national prevalence of Cryptosporidium cattle infections was 15.4% in pooled rectal fecal swab samples from post-weaned calves and 16.1% in adult cows. Sanger sequence analysis of the SSU rRNA gene target revealed that C. bovis, C. andersoni and C. ryanae occurred in both adults and post-weaned calves, with C. bovis as the predominant species detected in pooled fecal swab samples of post-weaned calves (9/18, 50%) and C. andersoni as the predominant species in cows (25/38, 66%). Cryptosporidium parvum was not observed in any of the pooled rectal swab samples from post-weaned calves but was observed in one mixed infection of C. bovis/C. parvum in an adult cow. The fifth species identified in this study was C. muris and was present in two adult cows. Low concentrations of oocyst equivalents, as measured by quantitative real-time PCR (qPCR) of the SSU rRNA gene copy number, were observed in a subset of cattle samples. Cryptosporidium andersoni concentrations varied from province to province, with the widest range and highest counts in cows from PE. In conclusion, oocysts from Cryptosporidium species observed in this study are shed into the environment, contributing to the environmental load. However, the Cryptosporidium species in the post-weaned calves and cows found in this study pose a lower risk to the dairy cattle than if they were infected with C. parvum. Similarly, these Cryptosporidium species pose only a small risk to public health as the three species are infrequently reported in humans globally and have not been reported in Canadians to date.

Effects of orally administered gabapentin, tramadol, and meloxicam on ocular variables in healthy dogs.

OBJECTIVE: To determine the effects of gabapentin, tramadol, and meloxicam on tear production, intraocular pressure (IOP), pupillary diameter, tear break-up time, and corneal touch threshold in healthy dogs when given orally for 3 days. ANIMALS: 9 healthy research Beagles. PROCEDURES: A randomized, blinded, case-crossover study with a 6-sequence, 3-treatment, and 3-period design was performed. A 7-day acclimation period was followed by 3 treatment phases, each with a 3-day treatment period followed by a 7-day washout period for 3 different drugs. Block randomization was used to group dogs for treatments with drug A (gabapentin), B (tramadol), or C (meloxicam). Measurements of tear production, IOP, pupillary diameter, tear break-up time, and corneal touch threshold were performed on a schedule. A generalized mixed-effects linear regression model was created for each ocular variable, accounting for repeated measures within individuals. RESULTS: Intraocular pressure was the only variable to have differed substantially between the first 5 and last 2 days of the acclimation period. When treatment phase, day, time of day, dog identification, baseline value, and eye were accounted for, the mean IOP was lower for dogs during treatment phases with gabapentin or tramadol, compared with meloxicam, but this difference was not considered clinically meaningful. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that a minimum 5-day acclimation period is necessary for IOP measurements to return to baseline in dogs. The statistically identified effect of gabapentin and tramadol on IOP in dogs of the present study warrants further investigation. It is possible that at higher dosages, or in dogs with glaucoma, this effect may become clinically significant.

Gap between producers and veterinarians regarding biosecurity on Quebec dairy farms.

As part of the ProAction on-farm program to implement national biosecurity requirements on dairy farms, Canadian veterinarians are called upon to complete biosecurity risk assessments. The objective of the present study was consequently to understand veterinarians' perceptions of biosecurity, and to compare perceptions among producer-veterinarian pairs. Questionnaires were administered to 106 producers from Quebec and their veterinarians (n = 82), and the answers of the producer-veterinarian pairs were compared. While most veterinarians reported it was easy to discuss biosecurity with their clients, most veterinarians and producers did not report discussing biosecurity. Moreover, when producers or veterinarians reported discussing biosecurity topics, there was no agreement amongst pairs. Veterinarians also misjudged how their clients perceived the importance and usefulness of biosecurity. Finally, veterinarians reported they had the knowledge and opportunity to assess and discuss biosecurity on dairy farms but lacked skills for evaluating farms and communicating their knowledge.

Différences entre les producteurs et les vétérinaires en matière de biosécurité dans les fermes laitières du Québec. Dans le cadre du programme à la ferme ProAction visant à mettre en oeuvre les exigences nationales de biosécurité dans les fermes laitières, les vétérinaires canadiens sont appelés à effectuer l'évaluation des risques reliés à la biosécurité. L'objectif de cette étude était, par conséquent, de comprendre la perception qu'ont les vétérinaires de la biosécurité et de comparer cette perception entre les paires producteurs-vétérinaires. Des questionnaires ont été administrés à 106 producteurs québécois et à leurs vétérinaires (n = 82). Les réponses des paires producteurs-vétérinaires ont été comparées. Alors que la plupart des vétérinaires ont déclaré qu'il était facile de discuter de biosécurité avec leurs clients, la plupart des vétérinaires et des producteurs n'ont pas déclaré en avoir discuté dans l'année précédant l'étude. De plus, lorsque les producteurs ou les vétérinaires ont rapporté avoir discuté de sujets liés à la biosécurité, il n'y avait pas d'accord entre les paires. Les vétérinaires ont également mal évalué la façon dont leurs clients percevaient l'importance et l'utilité des mesures de biosécurité. Enfin, les vétérinaires ont indiqué qu'ils avaient les connaissances et la possibilité d'évaluer et de discuter de la biosécurité dans les exploitations laitières, mais manquaient de compétences pour évaluer les exploitations et communiquer leurs connaissances.(Traduit par Dr José Denis-Robichaud).

Control of paratuberculosis: who, why and how. A review of 48 countries.

Paratuberculosis, a chronic disease affecting ruminant livestock, is caused by Mycobacterium avium subsp. paratuberculosis (MAP). It has direct and indirect economic costs, impacts animal welfare and arouses public health concerns. In a survey of 48 countries we found paratuberculosis to be very common in livestock. In about half the countries more than 20% of herds and flocks were infected with MAP. Most countries had large ruminant populations (millions), several types of farmed ruminants, multiple husbandry systems and tens of thousands of individual farms, creating challenges for disease control. In addition, numerous species of free-living wildlife were infected. Paratuberculosis was notifiable in most countries, but formal control programs were present in only 22 countries. Generally, these were the more highly developed countries with advanced veterinary services. Of the countries without a formal control program for paratuberculosis, 76% were in South and Central America, Asia and Africa while 20% were in Europe. Control programs were justified most commonly on animal health grounds, but protecting market access and public health were other factors. Prevalence reduction was the major objective in most countries, but Norway and Sweden aimed to eradicate the disease, so surveillance and response were their major objectives. Government funding was involved in about two thirds of countries, but operations tended to be funded by farmers and their organizations and not by government alone. The majority of countries (60%) had voluntary control programs. Generally, programs were supported by incentives for joining, financial compensation and/or penalties for non-participation. Performance indicators, structure, leadership, practices and tools used in control programs are also presented. Securing funding for long-term control activities was a widespread problem. Control programs were reported to be successful in 16 (73%) of the 22 countries. Recommendations are made for future control programs, including a primary goal of establishing an international code for paratuberculosis, leading to universal acknowledgment of the principles and methods of control in relation to endemic and transboundary disease. An holistic approach across all ruminant livestock industries and long-term commitment is required for control of paratuberculosis.

Reproductive management practices on dairy farms: The Canadian National Dairy Study 2015.

The objectives of this cross-sectional study were to characterize reproductive management practices on Canadian dairy farms and describe differences based on regional and demographic factors. A questionnaire was offered to all licensed Canadian dairy producers and included 189 questions regarding producer and farm background information, herd dynamics, biosecurity, disease prevalence, calf health, animal welfare, milking practices, reproduction, and internet use. Twenty-four questions were related to estrus detection, hormonal protocols for reproduction, insemination, and pregnancy diagnosis. A total of 1,373 producers responded to the survey, representing a response rate of 12.5%. Estrus detection practices in lactating cows were associated with herd size, barn type, region, organic production, breeding method, and age of respondent. The most commonly used estrus-detection method in cows was visual (51.0% of farms for first insemination; 45.5% for subsequent inseminations). Estrus detection for nulliparous heifers was associated with herd size, barn type, region, and breeding method, with visual detection also the most common method for heifers (71.3% of farms). Eighty percent of farms used strictly artificial insemination, 2.8% used natural service only, and 16.8% used a combination of artificial insemination and natural service. Breeding method was associated with herd size, barn type, region, and education level of the respondent. Pregnancy diagnosis method was associated with herd size, barn type, region, and organic production. Ultrasound was the most commonly used method of pregnancy diagnosis (used by 52.2% of farms). Sixty-nine percent of farms rechecked cows for pregnancy, and rectal palpation was the most commonly used method (employed by 48.7%). Reproductive management practices vary considerably among Canadian dairy farms and decisions are associated with farm-level factors, including region, herd size, and barn type, as well as producer-level factors, such as age, managerial role, and education level.

Prevalence of Mycobacterium avium ssp. paratuberculosis infections in Canadian dairy herds.

Johne's disease is a progressive, chronic disease with inflammation of the small intestine of ruminants caused by Mycobacterium avium ssp. paratuberculosis (MAP). Accurately estimating prevalence of MAP infections is important when controlling spread of infection or monitoring effectiveness of control programs. In the absence of a consistent test method used in prevalence studies across Canada, prevalence estimates among regions and programs cannot be compared. The aim of the current study was to estimate and compare prevalence of MAP infection in Western Canada, Ontario, Québec, and the Atlantic provinces, as well as among varying herd sizes and housing types. On 362 dairy farms located in all 10 provinces of Canada, environmental samples were collected and cultured for detection of MAP. For each herd, 1 sample was collected from the lactating cow area and manure storage. An additional environmental sample was collected from the area where breeding-age heifers were housed. Using prior distributions from previous research, diagnostic sensitivity and specificity were calculated to assess the ability of only 2 environmental samples (manure storage and lactating cow area) to identify MAP-positive farms, resulting in a sensitivity and specificity of 38 and 100%, respectively. We found no difference in sensitivity and specificity when including breeding-age heifers environmental samples. Test characteristics were applied to environmental culture results from the 362 participating farms in all 4 regions, resulting in true prevalence estimates of 66% for farms in Western Canada, 54% in Ontario, 24% in Québec, and 47% in Atlantic Canada. Herds housed in tiestalls had lower prevalence than freestall-housed herds, and herds with 101-150 and >151 cows had higher prevalence than herds with ≤100 cows. This was the first time MAP prevalence was determined using 1 detection method, performed in 1 laboratory, and within a single year across Canada, enabling direct comparisons of prevalence among regions, housing types, and herd sizes.

Canadian National Dairy Study: Heifer calf management.

In the past decade, substantial changes have occurred in the way dairy heifer calves are managed. The objectives of this study, part of phase I of the 2015 Canadian National Dairy Study, were to examine heifer calf health and adoption of rearing practices, and to explore factors associated with different rearing strategies on Canadian dairy farms. The questionnaire was open to all licensed dairy producers in Canada and had a 12% response rate (n = 1,373). Fifty-one percent of respondents reported never allowing heifer calves to nurse their dam, and 17% always removed calves within 30 min of birth. Sixty-seven percent reported always feeding heifer calves 4 L of colostrum within 12 h of birth; 17% always fed colostrum between 2100 and 0400 h; 5% pasteurized all colostrum fed on farm. Seventy-seven percent of respondents reported calving and stillbirth information for 2014; the mean reported stillbirth rate was 4.9% (SD = 3.3). Forty percent housed calves in individual pens, 34% in group pens, 21% in individual hutches, 2% reported tethering calves, and 1% used group hutches. Of those who housed calves in groups, 59% reported a maximum group size of 3 to 10 calves, 31% reported a pair (2) of calves per pen or hutch, and 10% reported a group >10 calves. The maximum amount of milk offered to calves per day during the preweaned period was a mean of 8 L (SD = 3). Fifty percent of respondents reported mortality data for 2014; mean preweaning mortality was 6.4% (SD = 8.3), and postweaning mortality was 2.4% (SD = 4.4). Over 95% of producers reported disbudding practices; 86% used cautery, 11% used surgical amputation, and 9% used caustic paste. Twenty-eight percent reported disbudding at less than 3 wk of age, 60% at 3 to 8 wk, and 22% at 8 to 16 wk; 5% of respondents reported dehorning at more than 16 wk of age. Sixty-six percent of cautery users reported use of local anesthetic, 33% used sedation, and 25% used a nonsteroidal anti-inflammatory drug (NSAID). Multivariable regression models showed that the use of local anesthetic when disbudding calves was associated with social media activity (odds ratio = 2.3) and high-speed internet access (odds ratio = 2.0), whereas sedation was associated with geographic region, and NSAID use was associated with disbudding at more than 3 wk of age. Exploring heifer rearing management practices, including adoption of best practices, may help focus future education and extension efforts. Poor reporting of mortality data may reflect a lack of recordkeeping on farm.

Identification of Mycobacterium avium subspecies paratuberculosis strains isolated from dairy goats and dairy sheep in Ontario, Canada.

The main objective of this study was to identify the circulating strains of Mycobacterium avium subspecies paratuberculosis (Map) in fecal isolates obtained from dairy goat (N = 29 farms) and dairy sheep (N = 21 farms) populations in Ontario, Canada. Further subtyping was performed to determine if there was adequate diversity between strains that could be used to establish Map transmission patterns. Type C was the dominant strain of Map isolates (95.2%) identified in dairy goats (n = 21). Sub-typing of the Type C strains, based on variable number tandem repeats (VNTR) and mycobacterial interspersed repetitive units, identified 3 VNTR types: INMV 1 (n = 10), INMV 2 (n = 10), and a type not previously identified (n = 1). Only 2 sheep isolates could be identified; both were Type S, sub-type III. Current typing methods demonstrate little Map diversity in the dairy goat population and are therefore of limited use to investigate infection patterns.

L'objectif principal de la présente étude était d'identifier les souches circulantes de Mycobacterium avium sous-espèces paratuberculosis (MAP) dans des échantillons fécaux obtenus de populations de chèvre laitière (N = 29 fermes) et de brebis laitière (N = 21 fermes) en Ontario, Canada. Du sous-typage supplémentaire a été effectué afin de déterminer s'il y avait suffisamment de diversité entre les souches qui permettrait d'établir des patrons de transmission de MAP. Il a été déterminé que le Type C était la souche dominante d'isolats de MAP (95,2 %) chez les chèvres laitières (n = 21), alors que deux isolats ovins ont été identifiés comme étant du Type S/sous-type III (n = 2). Le sous-typage des souches du Type C, basé sur le nombre variable de séquences répétées en tandem (VNTR) et les unités répétitives entrecoupées des mycobactéries, a permis d'identifier trois types de VNTR : INMV 1 (n = 10), INMV 2 (n = 10), et un type encore non-identifié (n = 1). Les méthodes actuelles de typage ne permettent de démontrer que peu de diversité de MAP dans la population de chèvre laitière et sont ainsi d'utilité limitée pour étudier les patrons d'infection.(Traduit par Docteur Serge Messier).

Prevalence of small ruminant lentivirus and Mycobacterium avium subsp. paratuberculosis co-infection in Ontario dairy sheep and dairy goats.

Infection with small ruminant lentiviruses (SRLV) causes a variety of chronic inflammatory conditions that limit production. Mycobacterium avium subsp. paratuberculosis (MAP) is also a major production-limiting disease of sheep and goats, which causes severe inflammation of the small intestine. Previous studies have indicated that both SRLV and MAP are widespread in small ruminants in Ontario. This study estimated the prevalence of SRLV and MAP co-infection. Serum samples that were previously tested for MAP infection were re-tested for SRLV. The apparent prevalence of co-infection was low, with 3.4% [95% confidence interval (CI): 1.9 to 5.9] and 14.3% (95% CI: 11.6 to 17.5) of sheep and goats respectively, positive for both infections. However, co-infection is widespread with 36.8% (95% CI: 19.1 to 59.1) and 71.4% (95% CI: 52.8 to 84.9) of sheep and goat farms with 1 or more co-infected animals. A significant association was found between SRLV seropositivity and MAP fecal culture (P = 0.021), suggesting that co-infected goats may be more likely to shed MAP in their feces.

L'infection par lentivirus des petits ruminants (SRLV) provoque une variété d'états inflammatoires chroniques qui limitent la production. Mycobacterium avium subsp. paratuberculose (MAP) est aussi une maladie limitant la production majeure de moutons et de chèvres, ce qui provoque une inflammation grave de l'intestin grêle. Des études antérieures ont indiqué que les deux infections de SRLV et MAP sont très répandues dans l'Ontario petits ruminants. Cette étude a été réalisée pour estimer la prévalence de SRLV et MAP co-infection. Des échantillons de sérum qui avaient été préalablement testés pour l'infection de MAP ont été utilisés pour détecter des anticorps spécifiques SLRV. La prévalence de la co-infection était faible, avec 3,4 % intervalle de confiance (95% IC : 1,9­5,9) et 14,3 % (95% IC : 11,6­17,5) des ovins et caprins, respectivement, positive pour les deux infections. Cependant la co-infection est très répandue avec 36,8 % (95% IC : 19,1­59,1) et 71,4 % (95% IC : 52,8­84,9) des élevages ovins et caprins avec un ou plusieurs animaux co-infecté. Une association significative a été trouvée entre SRLV et séropositivité MAP culture fécale (P = 0,021), ce qui suggère que les chèvres co-infectés peuvent être plus susceptibles de jeter le MAP dans leurs excréments.(Traduit par les auteurs).

Evaluation of fecal culture and fecal RT-PCR to detect Mycobacterium avium ssp. paratuberculosis fecal shedding in dairy goats and dairy sheep using latent class Bayesian modeling.

BACKGROUND: The study's objective was to evaluate the ability of fecal culture (FCUL) and fecal PCR (FPCR) to identify dairy goat and dairy sheep shedding Mycobacterium avium ssp. paratuberculosis. A cross-sectional study of the small ruminant populations was performed in Ontario, Canada between October 2010 and August 2011. Twenty-nine dairy goat herds and 21 dairy sheep flocks were visited, and 20 lactating females > two years of age were randomly selected from each farm resulting in 580 goats and 397 sheep participating in the study. Feces were collected per rectum and cultured using the BD BACTEC™ MGIT™ 960 system using a standard (49 days) and an extended (240 days) incubation time, and underwent RT-PCR based on the hsp-X gene (Tetracore®). Statistical analysis was performed using a 2-test latent class Bayesian hierarchical model for each species fitted in WinBUGS. RESULTS: Extending the fecal culture incubation time statistically improved FCUL sensitivity from 23.1 % (95 % PI: 15.9-34.1) to 42.7 % (95 % PI: 33.0-54.5) in dairy goats and from 5.8 % (95 % PI: 2.3-12.4) to 19.0 % (95 % PI: 11.9-28.9) in dairy sheep. FPCR demonstrated statistically higher sensitivity than FCUL (49 day incubation) with a sensitivity of 31.9 % (95 % PI: 22.4-43.1) in goats and 42.6 % (95 % PI: 28.8-63.3) in sheep. CONCLUSIONS: Fecal culture demonstrates such low sensitivity at the standard incubation time it cannot be recommended as a screening test to detect shedding of MAP in either goats or sheep. Extending the incubation time resulted in improved sensitivity; however, it is still disappointingly low for screening purposes. Fecal PCR should be the screening test of choice in both species; however, it is important to recognize that control programs should not be based on testing alone when they demonstrate such low sensitivity.

Paratuberculosis on small ruminant dairy farms in Ontario, Canada: A survey of management practices.

A cross-sectional study was undertaken (October 2010 to August 2011) to determine the risk factors for dairy goat herds and dairy sheep flocks testing positive for paratuberculosis (PTB) in Ontario, Canada. A questionnaire was administered to 50 producers during a farm visit in which concurrently, 20 randomly selected, lactating animals over the age of 2 years underwent sampling for paratuberculosis testing. Only 1 of 50 farms (2.0%) was closed to animal movement, whereas 96.6% of dairy goat farms and 94.1% of sheep farms purchased livestock from other producers. Only 10.3% of dairy goat, and no dairy sheep farms used artificial insemination. Manure was spread on grazing pastures by 65.5% and 70.6% of dairy goat and dairy sheep farms, respectively. Because of the high true-prevalence of paratuberculosis infection detected, no risk factor analysis could be performed. This study demonstrates that biosecurity practices conducive to transmission of PTB are highly prevalent in Ontario small ruminant dairy farms.

La paratuberculose dans les fermes laitières de petits ruminants de l'Ontario, au Canada : enquête sur les pratiques de gestion. Une étude transversale (d'octobre 2010 à août 2011) a été entreprise afin de déterminer les facteurs de risque pour les troupeaux de chèvres laitières et de brebis laitières obtenant des résultats positifs pour la paratuberculose (PTB) en Ontario, au Canada. Un questionnaire a été soumis à 50 producteurs durant une visite à la ferme pendant laquelle, parallèlement, 20 animaux en lactation âgés de plus de 2 ans, qui étaient choisis au hasard, ont subi un prélèvement pour un test de paratuberculose. Seulement 1 des 50 fermes (2,0 %) était fermée au mouvement des animaux, tandis que 96,6 % des fermes de chèvres laitières et 94,1 % des fermes de brebis achetaient des animaux d'autres producteurs. Seulement 10,3 % des fermes de chèvres laitières, et aucune ferme de brebis laitières, avaient eu recours à l'insémination artificielle. Le fumier était épandu dans les pâturages par 65,5 % et 70,6 % des fermes de chèvres laitières et de brebis laitières, respectivement. En raison de la prévalence réelle élevée détectée pour l'infection par la paratuberculose, aucune analyse de facteur de risque n'a pu être réalisée. Cette étude démontre que les pratiques de biosécurité propices à la transmission de la PTB sont hautement prévalentes dans les fermes de petits ruminants de l'Ontario.(Traduit par Isabelle Vallières).

Prevalence of paratuberculosis in the dairy goat and dairy sheep industries in Ontario, Canada.

A cross-sectional study was undertaken (October 2010 to August 2011) to estimate the prevalence of paratuberculosis in the small ruminant dairy industries in Ontario, Canada. Blood and feces were sampled from 580 goats and 397 sheep (lactating and 2 y of age or older) that were randomly selected from 29 randomly selected dairy goat herds and 21 convenience-selected dairy sheep flocks. Fecal samples were analyzed using bacterial culture (BD BACTEC MGIT 960) and polymerase chain reaction (Tetracore); serum samples were tested with the Prionics Parachek enzyme-linked immunosorbent assay (ELISA). Using 3-test latent class Bayesian models, true farm-level prevalence was estimated to be 83.0% [95% probability interval (PI): 62.6% to 98.1%] for dairy goats and 66.8% (95% PI: 41.6% to 91.4%) for dairy sheep. The within-farm true prevalence for dairy goats was 35.2% (95% PI: 23.0% to 49.8%) and for dairy sheep was 48.3% (95% PI: 27.6% to 74.3%). These data indicate that a paratuberculosis control program for small ruminants is needed in Ontario.

Prévalence de la paratuberculose dans l'industrie des chèvres et des brebis laitières en Ontario, au Canada. Une étude de prévalence a été entreprise (d'octobre 2010 à août 2011) afin d'estimer la prévalence de la paratuberculose dans les industries laitières des petits ruminants en Ontario, au Canada. Du sang et des fèces ont été prélevés auprès de 580 chèvres et de 397 brebis (en lactation et âgées de 2 ans et plus) qui ont été choisies au hasard parmi 29 troupeaux de chèvres laitières et 21 troupeaux de brebis laitières choisis au hasard. Des échantillons de fèces ont été analysés à l'aide d'une culture bactérienne (BD BACTEC MGIT 960) et d'une amplification en chaîne par la polymérase (Tetracore); des échantillons de sérum ont été analysés à l'aide d'un ELISA Prionics Parachek. À l'aide d'un modèle Bayesien de variable à classe latente permettant de comparer 3 tests imparfaits, la véritable prévalence à la ferme a été estimée à 83,0 % (IP de 95 % : 62,6 %­98,1 %) pour les chèvres laitières et à 66,8 % (IP de 95 % : 41,6 %­91,4 %) pour les brebis laitières. La véritable prévalence à la ferme pour les chèvres laitières était de 35,2 % (IP de 95 % : 23,0 %­49,8 %) et et de 48,3 % (IP de 95 % : 27,6 %­74,3 %) pour les brebis laitières. Ces données signalent le besoin d'un programme de contrôle de la paratuberculose en Ontario.(Traduit par Isabelle Vallières).