Bovine astrovirus and its role in lymphocytic encephalitis in cattle in Ontario, Canada, 1988-2019.

Astroviruses have been found in cattle and other species with encephalitis. Our objective was to determine the frequency of neurotropic bovine astrovirus (BoAstV) in cases of encephalitis in cattle ≥ 4-mo-old. Of 56 cases of idiopathic lymphocytic encephalitis examined retrospectively (1988-2019), fixed brain from 11 cases (19%) tested positive by semi-quantitative RT-PCR for BoAstV CH13/NeuroS1. None of the control cases tested positive, including 32 with other forms of encephalitis and 40 with no neurologic disease. Most astrovirus-positive cases were 1-2-y-old, with a range of 7 mo to 7 y, and affected both beef and dairy breeds with wide geographic distribution. BoAstV-positive cases had acute onset of neurologic signs of 12 h to 7 d before death or euthanasia. Affected cattle had lymphocytic inflammation throughout the brain including cerebrum, thalamus, midbrain, cerebellum, medulla oblongata, and spinal cord, and affecting gray and white matter. Further PCR testing identified a possible cause in 9 of the 45 (20%) remaining idiopathic cases of lymphocytic encephalitis, including eastern equine encephalitis virus, Listeria monocytogenes, bovine viral diarrhea virus, bovine alphaherpesvirus 1, and ovine gammaherpesvirus 2 (malignant catarrhal fever); we found no cases of infection by West Nile virus, rabies virus, or Chlamydia spp. No cause was identified in 36 of 56 (64%) cases of lymphocytic encephalitis. We frequently identified neurotropic BoAstV in cases of lymphocytic encephalitis that had no previously identified cause. Neurotropic BoAstV infections had gone undetected for decades, but the frequency of BoAstV infections has not increased among contemporary cases.

Development of interactive dashboards for monitoring endemic animal pathogens in Ontario, Canada: Ontario interactive animal pathogen dashboards.

The advancement of web-based technologies makes it possible to build user interfaces or web pages that present and summarize complex data in easy-to-read graphical formats that emphasize key information. Taking advantage of this technologic progress, we addressed the need for real-time visualizations of trends for major pathogens in the largest livestock industries in Ontario: poultry, swine, and cattle. These visualizations were built using test data from the laboratory information management system of the Animal Health Laboratory at the University of Guelph, a large veterinary diagnostic laboratory in Ontario. The data were processed using R software and used to construct interactive and dynamic visualizations using Tableau Desktop v.2021.4 (Tableau Software). We designed 12 dashboards: in chickens-influenza A virus, fowl adenovirus, infectious bronchitis virus, and infectious laryngotracheitis virus; in turkeys-influenza A virus; in swine, influenza A virus, rotavirus, and porcine reproductive and respiratory syndrome virus; in cattle-bovine viral diarrhea virus, Mycoplasma bovis, Salmonella Dublin in individual samples, and Salmonella Dublin in bulk tank milk samples. Data for each pathogen are presented in 2 dashboards. One shows the data of the last 10 y (general view) and the other the data of the last 3 y, but in more detail (comprehensive view). Information on gaining access to all dashboards is available at https://iapd.lsd.uoguelph.ca/. The visualizations provide near-real-time access to aggregated assay results for selected pathogens for veterinarians, animal health regulatory agencies, researchers, and other users who are interested in livestock pathogen surveillance.

The impact of the initial public health response to COVID-19 on swine health surveillance in Ontario.

COVID-19 restrictions and the pandemic have affected animal health and food production through the disease's effects on human activities. COVID-19 impact on swine health surveillance can be assessed by investigating submissions and test positivity for pathogens before and after COVID-19 restrictions. PRRSV, Influenza A virus, Mycoplasma hyopneumoniae and PCV-2 are considered important and economically challenging respiratory diseases for the swine populations. By reviewing test results from swine samples submitted for diagnostic testing to a regional diagnostic laboratory, and by assessing total submissions, total positive tests, and the proportion of positive tests at weekly intervals with time series techniques and generalized linear regression models, we evaluated COVID-19's impact on the monitoring of these respiratory pathogens in Ontario, Canada. We classified weeks that fell from week 12 through week 24 in each year as pandemic equivalent weeks and the non-pandemic weeks included all other weeks. The pandemic period in 2020 resulted in a significantly higher number of submissions (p < 0.05) and PRRSV positive submission counts (p < 0.05) when compared to equivalent time periods in previous years; however, no changes could be detected in the odds of weekly PRRSV submission positivity. Weekly positive proportions of PCV-2 tests were higher during the pandemic period in 2020 compared with the pandemic equivalent period in 2018 and 2017. The counts of submissions that requested tests for PRRSV, Influenza A virus and M. hyopneumonia combined, as well as the number of submissions and the proportions of submissions that tested negative for these multiple respiratory pathogens were not significantly different between the pandemic period in 2020 and other periods examined. Our findings indicate that swine producers, in conjunction with various private and public veterinary support services, continued monitoring and performing diagnostic screening on farms for economically important animal diseases despite complications resulting from COVID-19 public health restrictions. PRRSV continues to have a serious impact on swine health. The absence of an increased proportion of negative tests for individual or groups of pathogens, or an accompanying increase in submissions during the 2020 pandemic period suggests that no new undetected pathogens with an impact on respiratory signs in swine were introduced during this time.

Identification of bovine astrovirus in cases of bovine non-suppurative encephalitis in eastern Canada.

Bovine astrovirus (BoAstV) was identified by reverse transcriptase polymerase chain reaction on brain tissue of 2 feedlot cattle that died of non-suppurative encephalitis. Sequencing demonstrated a high degree of identity with neurotropic US and Swiss BoAstV strains. To our knowledge, this is the first confirmed report of BoAstV-associated encephalitis in cattle residing in eastern Canada.

Identification de l'astrovirus bovin dans des cas d'encéphalite bovine non suppurative dans l'Est du Canada. L'astrovirus bovin (BoAstV) a été identifié par amplification en chaîne par la polymérase avec la transcriptase réverse sur des tissus du cerveau de 2 bovins de parcs d'engraissement qui étaient morts d'encéphalite non suppurative. Le séquençage a démontré un haut niveau d'homologie avec les souches neurotropiques américaine et suisse de BoAstV. À notre connaissance, il s'agit du premier rapport confirmé d'une encéphalite associée à BoAstV chez le bétail résidant dans l'Est du Canada.(Traduit par Isabelle Vallières).

A prospective study of sheep and goat abortion using real-time polymerase chain reaction and cut point estimation shows Coxiella burnetii and Chlamydophila abortus infection concurrently with other major pathogens.

From 2009 to 2011, 163 sheep and 96 goat abortion submissions were received at the Animal Health Laboratory, University of Guelph, Ontario, Canada, for gross and histologic examination, as well as real-time polymerase chain reaction (PCR) testing for Chlamydophila abortus and/or Coxiella burnetii. Additional testing included immunohistochemistry for Toxoplasma gondii and Chlamydophila spp., routine bacterial culture and selective culture for Campylobacter spp., examination of modified acid-fast-stained placenta smears, enzyme-linked immunosorbent assay testing for Chlamydophila spp., and virus isolation. The final diagnosis made for each case by individual pathologists, based on gross and histologic lesions, as well as ancillary testing, was used as a standard to determine the significance of C. abortus and C. burnetii infection. Coxiella burnetii was identified by real-time PCR in 113 of 163 (69.0%) and 72 of 96 (75%) sheep and goat abortion submissions, respectively, but was considered to be significant in causing abortion in only 11 of 113 (10%) sheep and 15 out of 72 (21%) goat submissions that tested positive. Chlamydophila abortus was identified by real-time PCR in 42 of 162 (26%) and 54 of 92 (59%) sheep and goat submissions, respectively, but was considered the cause of the abortion in 16 of 42 (38%) sheep and 34 of 54 (63%) goat submissions that tested positive. Optimal sensitivity and specificity cut points for the real-time PCR copy number for C. abortus and C. burnetii were determined using the final pathology diagnosis as the reference test.

Evidence of Parelaphostrongylus tenuis infections in free-ranging elk (Cervus elaphus) in southern Ontario.

The antemortem detection of a Parelaphostrongylus tenuis infection in a free-ranging wild elk (Cervus elaphus) in southern Ontario is documented. Postmortems on other free-ranging elk that died during 2000-2005 indicated that 59% (17/29) were infected with P. tenuis, based on presence of lesions in the brain.

Agreement among surgical pathologists evaluating routine histologic sections of digits amputated from cats and dogs.

Agreement among pathologists interpreting histologic specimens is an area of interest within human pathology, but little work in this area has been reported in the veterinary literature. Agreement among pathologists evaluating routine histologic sections of amputated digits from cats and dogs submitted to multiple diagnostic centers was examined. Histologic sections from surgical specimens were reviewed in a blinded fashion by two pathologists, and a comparison to the original diagnosis, as stated in the diagnostic report, was recorded. A total of 513 cases were reviewed, and complete agreement was reached in 409 (79.7%). Of the 104 instances of disagreement, 77 (74.0%) were considered to be of clinical significance. The diagnosis of keratoacanthoma was disagreed with in 19 of 21 diagnoses (90.4%). No other individual diagnosis was similarly disputed. The overall level of disagreement is large and is similar to that reported in human pathology and suggests that further study of this issue would be useful in veterinary pathology.

Porcine circovirus 2-associated disease in Eurasian wild boar.

Porcine circovirus 2 (PCV2) was first identified in high-health herds of domestic swine and was associated with a debilitating disease called postweaning multisystemic wasting syndrome (PMWS). Most subsequent studies have indicated that PCV2 infects only swine but there is little information on porcids other than improved breeds of domestic swine. Multisystemic disease was reported in a group of Eurasian wild boars raised under free-range conditions. Affected young pigs had pneumonia and enteritis and were cachectic. Porcine circovirus 2 was identified in affected tissue by immunohistochemistry and in situ hybridization, and a PCV2-like virus was isolated from pooled organs. The open reading frame (ORF2) of the isolated PCV2 had a 98.7% homology with the ORF2 of a reference PCV2 isolate. These diagnostic data indicate that PCV2 can infect and cause disease in Sus scrofa subspecies other than domestic swine.