Lessons from CanSpotASF: Moving towards risk-based African Swine Fever surveillance with rule-out testing in Western Canada.

African swine fewer (ASF) is a serious disease present in Africa, Eurasia, and the Caribbean but not in continental North America. CanSpotASF describes the ASF surveillance in Canada as a phased in approach. The first enhancement to the passive surveillance was the risk-based early detection testing (rule-out testing) where eligible cases were tested for ASF virus (ASFv). The objective was to describe how the eligibility criteria were applied to cases in western Canada. In particular, to assess if cases tested for ASFv had eligible conditions and if pathology cases with eligible conditions were tested for ASFv based on the data collated by Canada West Swine Health Intelligence Network (CWSHIN) from British Columbia, Alberta, Saskatchewan, and Manitoba. The study period was August 2020 to December 2022 and the data included two study laboratories. We found that over 90% of cases tested for ASFv had eligible conditions as defined in CanSpotASF. The eligibility criteria were applied at three stages of the disease investigation process: 1) the clinical presentation in the herd; 2) at the initial laboratory assessment; and 3) the final pathology diagnosis. At the two study laboratories the proportion of all submitted cases (culture, serology, PCR, pathology) tested for ASFv was very low 1%. However, in the pathology cases specifically targeted in CanSpotASF, and the proportion of tested cases was 12%. In addition, for eligible pathology cases (eligible diagnosis or test) the proportion tested was higher 15%. These results indicated that CanSpotASF targeted herds with submissions for pathological examination and to some degree eligible conditions which would be herds with health issues (known or unknown). We interpret this as a first step towards risk-based surveillance with health as the defining factor.

A 13-year retrospective study of equine abortions in Canada.

Objective: The purpose of this study was to identify the most common causes of equine abortion in Canada, and to compare findings to similar reports from other countries. Animal: Equine. Procedure: Necropsy reports from 901 equine abortion cases were acquired from provincial veterinary diagnostic laboratories across Canada. The final diagnosis was classified into basic abortion causes (infectious, non-infectious, unknown) and into primary and secondary categories for analysis. Results: Non-infectious causes of abortion were the most frequently identified in Canada, with fetoplacental causes, including umbilical cord torsion or placental insufficiency, being the most common primary diagnosis category. Streptococcus and Escherichia were the bacterial species most often identified as causing infectious abortions, whereas equine herpesvirus-1 was implicated in all viral abortions identified. Conclusion: The high rate of non-infectious causes of abortion was similar to previous studies conducted in the United Kingdom. This finding was somewhat dissimilar to the USA, which had higher rates of infectious abortions, despite Canada's geographic proximity to the USA. The reason for variations among countries in equine abortion causes is unknown. Clinical relevance: The large number of fetoplacental-related abortions identified in this study emphasized the need for submission of both the fetus and placenta, if possible, to increase the probability of a diagnosis. In addition, the high rate of unidentified diagnoses suggests a need for further study into both non-infectious and infectious causes of equine abortion, including potential development of new diagnostic tests or markers.

Objectif: Le but de cette étude était d'identifier les causes les plus courantes d'avortement chez les équidés au Canada et de comparer les résultats à des rapports similaires provenant d'autres pays. Animal: Chevaux. Procédure: Les rapports de nécropsie de 901 cas d'avortements équins ont été obtenus auprès de laboratoires provinciaux de diagnostic vétérinaire à travers le Canada. Le diagnostic final a été classé en causes d'avortement de base (infectieuses, non infectieuses, inconnues) et en catégories primaires et secondaires pour analyse. Résultats: Les causes non-infectieuses d'avortement étaient les plus fréquemment identifiées au Canada, les causes foetoplacentaires, y compris la torsion du cordon ombilical ou l'insuffisance placentaire, étant la catégorie de diagnostic principal la plus courante. Les espèces bactériennes des genres Streptococcus et Escherichia étaient les plus souvent identifiées comme étant à l'origine d'avortements infectieux, alors que l'herpèsvirus équin-1 était impliqué dans tous les avortements viraux identifiés. Conclusion: Le taux élevé de causes non-infectieuses d'avortement était similaire aux études précédentes menées au Royaume-Uni. Cette observation était quelque peu différente de celles des États-Unis, qui avaient des taux plus élevés d'avortements infectieux, malgré la proximité géographique du Canada avec les États-Unis. La raison des variations entre les pays dans les causes d'avortement équin est inconnue. Pertinence clinique: Le grand nombre d'avortements liés aux causes foetoplacentaires identifiés dans cette étude a souligné la nécessité de soumettre à la fois le foetus et le placenta, si possible, pour augmenter la probabilité d'un diagnostic. En outre, le taux élevé de diagnostics non identifiés suggère la nécessité d'une étude plus approfondie des causes non-infectieuses et infectieuses de l'avortement équin, y compris le développement potentiel de nouveaux tests de diagnostic ou marqueurs.(Traduit par Dr Serge Messier).

Development and evaluation of a new method to combine clinical impression survey data with existing laboratory data for veterinary syndromic surveillance with the Canada West Swine Health Intelligence Network (CWSHIN).

The Canada West Swine Health Intelligence Network (CWSHIN) is a surveillance system imbedded in an intelligence network. It has been conducting syndromic surveillance in the four western provinces of Canada since 2012. The quarterly activities include repeated clinical impression surveys, compilation of laboratory data, discussion of trends with an expert group (practitioners, laboratory diagnosticians) and swine health reports for producers and swine practitioners. However, due to the lack of standardized population identifiers across data sources usual methods of combining data could not be applied and the collated data were not being fully utilized and analysed. Therefore in 2019, CWSHIN underwent a substantial review resulting in the "Next Generation CWSHIN". The objectives of this study were to develop and evaluate a new data merging method to combine CWSHIN's clinical impression survey and laboratory data; and to provide examples of analyses and modeling based on these data. The data for analysis were restricted to repeated clinical impression surveys (2019-2020) from veterinary practitioners and laboratory diagnostic data (2016-2020). Merging surveillance data from existing sources can be challenging. Therefore, as an alternative to merge data using a hierarchy of population identifiers, we developed a Disease Map to link surveillance data from all our data-sources. The resulting Data Repository allowed monitoring of temporal trends of syndromes, clinical diseases, and laboratory identified organisms, but it cannot provide estimates of disease occurrence. Two main reasons were the lack of denominators and using existing data on routine diagnostic tests. Therefore, discussion in the expert group (veterinary practitioners, laboratory diagnosticians, swine health experts) was critical to the system's success. Based on repeated clinical impression surveys a stochastic scenario tree model for freedom from Foot and Mouth Disease (CWSHIN Blister model) was also developed. In conclusion, the method to link existing data systems from multiple divergent sources by means of a Disease Map improved CWSHIN's veterinary syndromic surveillance. Together the Data Repository and Disease map provided flexibility to monitor temporal trends, define populations and diseases, and allow analysis. However, it is critical that the surveillance is coupled with a good intelligence network that can help interpret the results and disseminate knowledge to veterinarians and producers.

Herd risk factors associated with sero-prevalence of Maedi-Visna in the Manitoba sheep population.

Disease associated with Maedi-Visna infection results in substantial economic losses in affected sheep producing areas of the world. A survey was conducted to estimate herd and individual seroprevalence in the province of Manitoba and evaluate risk factors for seropositive herds. Of 2207 sheep sampled from 77 selected sheep flocks, the animal level seroprevalence was 2.47% and herd level seroprevalence was 25.10%. The herd-level factors of presence of clinical skin disease, herd size of > 70, history of musculoskeletal/lameness abnormalities, and the purchase of new stock (> 50) in the last 1 to 5 y, showed significant associations with seropositive herd status. The study documented a remarkable stability of low seroprevalence in the province over a 20-year period in the absence of a systematic disease control program.