Bronchopneumonia with interstitial pneumonia in beef feedlot cattle: Characterization and laboratory investigation.

Bronchopneumonia with interstitial pneumonia (BIP) has been considered a variant of acute interstitial pneumonia (AIP) rather than a distinct disease. This study compared 18 BIP, 24 bronchopneumonia (BP), and 13 AIP cases in feedlot beef cattle. Grossly, BIP cases typically had cranioventral lung lesions of similar morphology and extent as BP cases, but the caudodorsal lung appeared overinflated, bulged on section, and had interlobular edema and emphysema. Gross diagnosis of BIP had 83% sensitivity and 73% specificity relative to histopathology. Histologic lesions of BIP in cranioventral areas were of chronic BP, while caudodorsal lesions included alveolar and bronchiolar damage and inflammation, interstitial hypercellularity, and multifocal hemorrhages. In BIP cases, cranioventral lung lesions were more chronic than caudodorsal lesions. Histologic scores and microbiology data were comparable in cranioventral lung of BIP versus BP cases and caudodorsal lung of BIP versus AIP cases, with differences reflecting a more chronic disease involving less virulent bacteria in BIP versus BP. Mycoplasma bovis infection was similarly frequent among groups, and a viral cause of BIP was not identified. Lesion morphology and similar blood cytokine concentrations among groups argued against sepsis as a cause of lung injury. Surfactant dysfunction was identified in BIP and BP, and was only partially the result of protein exudation. These and other findings establish BIP as a distinct condition in which chronic cranioventral BP precedes acute caudodorsal interstitial lung disease, supporting a role of chronic inflammation in heightened sensitivity to 3-methylindole or another lung toxicant.

Laboratory investigation of cases of fatal bacterial pneumonia in dairy cows.

Objective: Bacterial bronchopneumonia occurs in mature dairy cows but much of the information is extrapolated from knowledge of the disease in calves. The study was prompted by perceptions of an increasing occurrence and a paucity of information on fatal Mannheimia haemolytica pneumonia in dairy cows in Ontario. The study objectives were to describe the seasonality, main pathogens involved, and suggested predisposing factors for cases of fatal bacterial bronchopneumonia in mature dairy cows submitted for postmortem examination to a diagnostic laboratory, and to evaluate if the frequency of such submissions has increased over time. Animals: Mature dairy cows. Procedure: Retrospective study of cases submitted for postmortem examination to a diagnostic laboratory from 2007-2020 that were diagnosed as bacterial bronchopneumonia. Results: Most of the postmortem cases of bacterial bronchopneumonia in dairy cows were submitted from November to February (54% of cases). Mannheimia haemolytica was isolated from lung of 61/101 cases. Viruses were only identified in 8/55 cases tested. A minority (29/92) of bacterial isolates had in vitro resistance to antimicrobials used to treat pneumonia. Frequently suggested predisposing factors included recent introductions or movement of animals, recent or imminent calving, inclement weather, concurrent diseases, and poor ventilation in barns. Conclusion and clinical relevance: This study describes seasonal and annual trends, major pathogens, antimicrobial resistance profiles, and suggested predisposing factors in Ontario dairy cows submitted to a diagnostic laboratory for postmortem investigation of pneumonia and provides insights for understanding why outbreaks occur.

Objectif: La bronchopneumonie bactérienne survient chez les vaches laitières matures, mais une grande partie de l'information est extrapolée à partir de la connaissance de la maladie chez les veaux. L'étude a été motivée par la perception d'une occurrence croissante et d'un manque d'information sur la pneumonie mortelle à Mannheimia haemolytica chez les vaches laitières en Ontario. Les objectifs de l'étude étaient de décrire la saisonnalité, les principaux agents pathogènes impliqués et les facteurs prédisposants suggérés pour les cas de bronchopneumonie bactérienne mortelle chez les vaches laitières matures soumises à un examen post-mortem à un laboratoire de diagnostic, et d'évaluer si la fréquence de telles soumissions a augmenté au fil du temps. Animaux: Vaches laitières matures. Procédure: Étude rétrospective des cas soumis pour examen post-mortem à un laboratoire de diagnostic, entre 2007 et 2020, qui ont été diagnostiqués comme une bronchopneumonie bactérienne. Résultats: La plupart des cas post-mortem de bronchopneumonie bactérienne chez les vaches laitières ont été soumis de novembre à février (54 % des cas). Mannheimia haemolytica a été isolée du poumon de 61/101 cas. Des virus n'ont été identifiés que dans 8/55 cas testés. Une minorité (29/92) d'isolats bactériens présentaient une résistance in vitro aux antimicrobiens utilisés pour traiter la pneumonie. Les facteurs prédisposants fréquemment suggérés comprenaient des introductions ou des déplacements récents d'animaux, un vêlage récent ou imminent, des conditions météorologiques défavorables, des maladies concomitantes et une mauvaise ventilation dans les étables. Conclusion et pertinence clinique: Cette étude décrit les tendances saisonnières et annuelles, les principaux agents pathogènes, les profils de résistance aux antimicrobiens et les facteurs prédisposants suggérés chez les vaches laitières de l'Ontario soumises à un laboratoire de diagnostic pour une enquête post-mortem sur la pneumonie et fournit des informations pour comprendre pourquoi les épidémies se produisent.(Traduit par Dr Serge Messier).

Emergence and Containment of Canine Influenza Virus A(H3N2), Ontario, Canada, 2017-2018.

Canine influenza virus (CIV) A(H3N2) was identified in 104 dogs in Ontario, Canada, during December 28, 2017-October 30, 2018, in distinct epidemiologic clusters. High morbidity rates occurred within groups of dogs, and kennels and a veterinary clinic were identified as foci of infection. Death attributable to CIV infection occurred in 2 (2%) of 104 diagnosed cases. A combination of testing of suspected cases, contact tracing and testing, and 28-day isolation of infected dogs was used, and CIV transmission was contained in each outbreak. Dogs recently imported from Asia were implicated as the source of infection. CIV H3N2 spread rapidly within groups in this immunologically naive population; however, containment measures were apparently effective, demonstrating the potential value of prompt diagnosis and implementation of CIV control measures.

Aquatic bird bornavirus 1 infection in a captive Emu (Dromaius novaehollandiae): presumed natural transmission from free-ranging wild waterfowl.

An adult female emu (Dromaius novaehollandiae) presented with anorexia, maldigestion, weight loss, and various subtle nervous deficits. After four months of unrewarding diagnostics, treatments, and supportive care, the emu was euthanized due to lack of clinical improvement and progressive weight loss. Gross pathology revealed a very narrow pylorus and multiple flaccid diverticula of the small intestines. Histopathological findings included severe lymphoplasmacytic encephalomyelitis and multifocal lymphocytic neuritis associated with the gastrointestinal tract. Immunohistochemistry and polymerase chain reaction on the brain were positive for an avian bornavirus (ABV), and partial sequencing of the matrix gene identified aquatic bird bornavirus-1 (ABBV-1), 100% identical to viruses circulating in wild Canada geese (Branta canadensis). As wild geese frequently grazed and defaecated in the emu's outdoor exhibit, natural transmission of ABBV-1 from free-ranging waterfowl to the emu was presumed to have occurred.

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).

Flock-level prevalence, geographical distribution, and seasonal variation of avian reovirus among broiler flocks in Ontario.

Avian reovirus (ARV) is an economically significant pathogen of broiler chickens. Our objective was to determine the prevalence, geographical distribution, and seasonal variation of ARV infection among commercial broiler flocks in Ontario, Canada during grow-out. A cross-sectional study of 231 randomly selected flocks was conducted from July 2010 to January 2012. Fifteen blood samples, 15 whole intestines, and 15 cloacal swabs per flock were collected at slaughter; ELISA and PCR were used to determine a flock's ARV exposure status. Avian reovirus prevalence was 91% (95% CI: 87 to 94). District alone did not significantly explain the overall variation in the prevalence of ARV (univariable logistic regression; P = 0.073), although geographical differences were identified. The odds of ARV presence were significantly lower in the summer/autumn compared to the winter/spring (univariable exact logistic regression; P < 0.001). There was no association between flock mortality and flock ELISA mean titer or PCR status.

Prévalence au niveau du troupeau, distribution géographique et variations saisonnières du réovirus aviaire parmi les troupeaux de poulets à griller en Ontario. Le réovirus aviaire (RVA) est un agent pathogène important sur le plan économique pour les poulets à griller. Notre objectif consistait à déterminer la prévalence, la distribution géographique et les variations saisonnières de l'infection par le RVA parmi les troupeaux de poulets à griller commerciaux en Ontario, au Canada, durant la phase d'engraissement. Une étude transversale de 231 troupeaux choisis au hasard a été réalisée de juillet 2010 à janvier 2012. Quinze échantillons sanguins, 15 intestins complets et 15 écouvillons cloacaux ont été prélevés à l'abattage; des tests ELISA et ACP ont été utilisés pour déterminer l'état d'exposition du troupeau au RVA. La prévalence du réovirus aviaire était de 91 % (IC de 95 % : de 87 à 94). Le district à lui seul ne peut pas expliquer significativement la variation générale dans la prévalence du RVA (régression logistique univariable; P = 0,073), quoique des différences géographiques ont été identifiées. Les risques de la présence du RVA étaient significativement inférieurs à l'été/automne comparativement à l'hiver/printemps (régression logistique exacte univariable; P < 0,001). Il n'y avait aucune association entre la mortalité du troupeau et le titre moyen ELISA du troupeau ou de son état d'ACP.(Traduit par Isabelle Vallières).

Identification of avian bornavirus in a Himalayan monal (Lophophorus impejanus) with neurological disease.

A one-year-old male Himalayan monal (Lophophorus impejanus) was presented for veterinary attention with a history of chronic wasting, weakness and ataxia. The bird died, and post-mortem findings included mild non-suppurative encephalitis and degenerative encephalopathy, lymphoplasmacytic myenteric ganglioneuritis (particularly of the proventriculus), and Wallerian degeneration of the sciatic nerves. Avian bornavirus (ABV) was identified in the brain by immunohistochemistry and reverse-transcriptase polymerase chain reaction. Sequencing of the reverse-transcriptase polymerase chain reaction product indicated the presence of ABV genotype 4, which is generally associated with disease in psittacine birds. Subsequent to the death of the pheasant, ABV genotype 4 was identified at autopsy from a juvenile white-bellied caique (Pionites leucogaster) in the same collection. We hypothesize that the pheasant became infected through contact with psittacine birds with which it shared an aviary. We believe this to be the first reported case of natural ABV infection in a bird in the Order Galliformes.

The first case of porcine epidemic diarrhea in Canada.

In January, 2014, increased mortality was reported in piglets with acute diarrhea on an Ontario farm. Villus atrophy in affected piglets was confined to the small intestine. Samples of colon content were PCR-positive for porcine epidemic diarrhea virus (PEDV). Other laboratory tests did not detect significant pathogens, confirming this was the first case of PED in Canada.

Premier cas de diarrhée épidémique porcine au Canada. En janvier 2014, une mortalité accrue a été signalée chez des porcelets atteints de diarrhée aiguë dans une ferme de l'Ontario. L'atrophie des villosités chez les porcelets touchés a été confinée au petit intestin. Des échantillons du contenu du côlon étaient positifs par RCP pour le virus de la diarrhée épidémique porcine (VDEP). D'autres tests de laboratoire n'ont pas détecté d'agents pathogènes importants, ce qui confirme qu'il s'agit du premier cas de DEP au Canada.(Traduit par Isabelle Vallières).

Investigation into the possibility of vertical transmission of avian bornavirus in free-ranging Canada geese (Branta canadensis).

To investigate the possibility of in ovo infection with avian bornavirus (ABV) in wild Canada geese (Branta canadensis), 53 eggs were opportunistically collected at various stages of embryonic development from 16 free-ranging goose nests at a large urban zoo site where ABV infection is known to be present in this species. ABV RNA was detected in the yolk of one of three unembryonated eggs using real-time reverse transcription polymerase chain reaction. ABV RNA was not identified in the brains from 23 newly hatched goslings or 19 embryos, nor from three early whole embryos. Antibodies against ABV were not detected in the plasma of any of the hatched goslings using an enzyme-linked immunosorbent assay. Possible reasons for the failure to detect ABV RNA in hatchlings or embryos include low sample size, eggs deriving from parents not actively infected with ABV, the testing of only brain tissue, and failure of the virus to replicate in Canada goose embryos. In conclusion, this preliminary investigation demonstrating the presence of ABV RNA in the yolk of a Canada goose egg provides the first evidence for the potential for vertical transmission of ABV in waterfowl.

Genotyping of infectious bronchitis viruses identified in Canada between 2000 and 2013.

Infectious bronchitis virus (IBV) was detected in 185 samples originating from chicken flocks of various commodity groups in Canada. Flocks with clinical signs such as respiratory challenge, sudden death, egg production problems, or nephropathogenic conditions, and randomly selected flocks sampled at slaughter as part of an Ontario broiler surveillance project, were included. Most samples were from Ontario and Québec; however, a small number from British Columbia, Nova Scotia, and Newfoundland and Labrador were also analysed. The nucleotide sequence of the spike (S) protein gene was compared with sequences available in GenBank. Based on their S gene sequence similarities, Canadian IBVs could be divided into nine genotypes belonging to four groups: Canadian variant virus, strain Qu_mv; the classic, vaccine-like viruses, Connecticut and Massachusetts; US variant-like virus strains, California 1734/04, California 99, CU_82792, Pennsylvania 1220/98 and Pennsylvania Wolg/98; and non-Canadian, non-US virus, strain 4/91. Based on the field situation, the effectiveness of current vaccination practices mostly based on Massachusetts and Connecticut-type vaccines appeared generally satisfactory for minimizing the damage due to infection with Canadian variant and US variant-like viruses. However, the recent outbreaks of severe respiratory disease and production problems in Ontario chicken flocks related to the incursion of IBV strain 4/91 were not prevented by standard vaccination protocols. It appears that IBV strain 4/91 has now become endemic in Ontario and the need for 4/91-type vaccines must be evaluated.

Flock prevalence of exposure to avian adeno-associated virus, chicken anemia virus, fowl adenovirus, and infectious bursal disease virus among Ontario broiler chicken flocks.

Samples from 231 randomly selected commercial broiler chicken flocks in Ontario were tested at slaughter for exposure to chicken anemia virus (CAV), fowl adenovirus (FAdV), and infectious bursal disease virus (IBDV). Fifteen blood samples per flock were collected and analyzed for the presence of antibodies against CAV, FAdV, and IBDV by ELISA or agar gel immunodiffusion test. Fifteen cecal tonsils and cloacal swabs per flock were analyzed for the presence of CAV, FAdV, and IBDV by PCR. The prevalence of exposure to avian adeno-associated virus (AAAV) was estimated by a PCR test on a subset of FAdV-PCR-positive samples from 178 flocks. Genotypes of FAdV and IBDV were identified on a subset of isolates (n = 353 and 45, respectively). The flock-level period prevalence of exposure to AAAV, CAV, FAdV, and IBDV during grow-out were 88.76% (95% CI: 84.08-93.45%), 77.06% (95% CI: 71.59-82.52%), 96.54% (95% CI: 94.16-98.91%), and 48.92% (95% CI: 42.42-55.41%), respectively. Results of a multivariable logistic regression model showed a significant association of exposure to FAdV with exposure to AAAV (OR = 18.57, 95% CI: 3.67-93.86, P = 0.004) but not with exposure to CAV (P = 0.7752) or exposure to IBDV (P = 0.2274). Pathogenic FAdV genotypes (FAdV-02, FAdV-08, and FAdV-11) constituted 39.38% of the isolates. The most-common IBDV genotypes identified were IBDV NC171 (60%) and IBDV 05SA8 (28.89%). This is the first large-scale study to estimate the baseline flock prevalence of exposure to AAAV, CAV, FAdV, and IBDV in commercial broiler flocks in Canada. Potentially pathogenic genotypes of FAdV and IBDV that can guide vaccine development and disease control efforts in Ontario were identified.

Detection of Leptospira spp. in wildlife reservoir hosts in Ontario through comparison of immunohistochemical and polymerase chain reaction genotyping methods.

A total of 460 kidney samples from wildlife (beavers, coyotes, deer, foxes, opossums, otters, raccoons, skunks) were obtained from road-kill and hunter/trapper donations in Ontario between January 2010 and November 2012. The objectives of the study were to detect Leptospira spp. by immunohistochemistry and polymerase chain reaction (PCR), to map presence of leptospires in wildlife relative to livestock and human populations, and to characterize positive samples by sequencing and comparison to leptospires known to affect domestic animals and humans. The proportion of samples that tested positive ranged from 0% to 42%, with the highest rates in skunks and raccoons. Leptospira spp. were present in kidneys of wildlife across Ontario, particularly in areas of high human density, and areas in which livestock populations are abundant. The PCR was too weak in most samples to permit genotyping and examination of the relationship between the leptospires found in this study and those affecting domestic animals and humans.

Détection deLeptospiraspp. chez des hôtes du réservoir faunique en Ontario par la comparaison des méthodes de génotypage de réaction immunohistochimique et d'amplification en chaîne par la polymérase. Un total de 460 échantillons de reins provenant de la faune (castors, coyotes, cerfs de Virginie, renards, opossums, loutres, ratons-laveurs, moufettes) ont été obtenus d'animaux tués sur la route et de dons de chasseurs et de trappeurs en Ontario entre janvier 2010 et novembre 2012. Les objectifs de l'étude étaient de détecter Leptospira ssp. par immunohistochimie et amplification en chaîne par la polymérase afin de cartographier la présence des leptospires dans la faune en rapport avec les populations de bétail et d'humains et de caractériser les échantillons positifs par le séquençage et la comparaison avec des leptospires reconnus comme affectant les animaux domestiques et les humains. La proportion des échantillons qui ont montré un résultat positif s'échelonnait de 0 à 42 %, et les taux les plus élevés se retrouvaient chez les moufettes et les ratons-laveurs. Leptospira spp. était présent dans les reins de la faune partout en Ontario, particulièrement dans les régions à forte densité humaine et dans les régions où les populations de bétail sont abondantes. L'amplification en chaîne par la polymérase était trop faible dans la plupart des échantillons pour permettre le génotypage et l'examen de la relation entre les leptospires trouvés dans cette étude et ceux touchant les animaux domestiques et les humains.(Traduit par Isabelle Vallières).

Canine distemper virus infection of vaccinal origin in a 14-week-old puppy.

The body of a 14-wk-old puppy (Canis familiaris) was submitted to the Animal Health Laboratory, University of Guelph, Ontario for postmortem examination following a history of intermittent anorexia and lethargy progressing to pyrexia, pruritic skin rash, mucoid nasal discharge, decreased mentation, dysphagia, muscle twitches, and focal seizures. Gross examination revealed rhinitis and pulmonary edema. Histologically, there was fibrinonecrotizing bronchopneumonia, tracheitis, and neutrophilic and lymphohistiocytic rhinitis; rarely within the cortical gray and white matter of the brain were small clusters of glial cells, with rare individual neutrophils in the choroid plexus. Although canine distemper was suspected, none of the usual supportive histologic lesions of distinct syncytial cells, viral inclusion bodies, or demyelinating leukoencephalitis were observed. Lung and brain tissues were PCR-positive for canine distemper virus (CDV), and CDV was detected immunohistochemically in the brain. The agent from the PCR-positive sample from the brain was genotyped and was a 99.9% match to the CDV Rockborn strain, indicating that the disease agent in our case was vaccinal in origin. Our unusual case highlights the possibility of reversion to virulence in a modified-live virus vaccine, and the occurrence of a disease in the absence of a full complement of the usual and compatible histologic lesions.

Genotyping of infectious bronchitis virus in Canada.

From 2014-2023, infectious bronchitis virus (IBV) was detected in 6,589 samples from Canada, and partial nucleotide (nt) sequences of the IBV spike protein (S) gene were determined for 1,678 samples. Based on their S gene nt sequence identities and origin, Canadian IBVs could be classified into 4 groups: 1) 50.3% were variant viruses related to strains described in the United States; 2) 45.6% were vaccine-like viruses; 3) 2.1% were Eurasian viruses; 4) 2.0% were Canadian variants. Outbreaks with IBVs related to strains CAL1734/04, 4/91, and DMV/1639/11 were often associated with more severe disease in all chicken commodity groups. With the emergence of numerous IBV strains, the severity of infection and number of affected flocks increased. Outbreaks with various IBV strains overlapped in their emergence, peaked, and regressed, but the introduction of DMV/1639/11 has resulted in a continuous field challenge since its first detection in 2015.

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.

Avian influenza viruses in wild birds in Canada following incursions of highly pathogenic H5N1 virus from Eurasia in 2021-2022.

Following the detection of novel highly pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b in Newfoundland, Canada, in late 2021, avian influenza virus (AIV) surveillance in wild birds was scaled up across Canada. Herein, we present the results of Canada's Interagency Surveillance Program for Avian Influenza in Wild Birds during the first year (November 2021-November 2022) following the incursions of HPAIV from Eurasia. The key objectives of the surveillance program were to (i) identify the presence, distribution, and spread of HPAIV and other AIVs; (ii) identify wild bird morbidity and mortality associated with HPAIV; (iii) identify the range of wild bird species infected by HPAIV; and (iv) genetically characterize detected AIV. A total of 6,246 sick and dead wild birds were tested, of which 27.4% were HPAIV positive across 12 taxonomic orders and 80 species. Geographically, HPAIV detections occurred in all Canadian provinces and territories, with the highest numbers in the Atlantic and Central Flyways. Temporally, peak detections differed across flyways, though the national peak occurred in April 2022. In an additional 11,295 asymptomatic harvested or live-captured wild birds, 5.2% were HPAIV positive across 3 taxonomic orders and 19 species. Whole-genome sequencing identified HPAIV of Eurasian origin as most prevalent in the Atlantic Flyway, along with multiple reassortants of mixed Eurasian and North American origins distributed across Canada, with moderate structuring at the flyway scale. Wild birds were victims and reservoirs of HPAIV H5N1 2.3.4.4b, underscoring the importance of surveillance encompassing samples from sick and dead, as well as live and harvested birds, to provide insights into the dynamics and potential impacts of the HPAIV H5N1 outbreak. This dramatic shift in the presence and distribution of HPAIV in wild birds in Canada highlights a need for sustained investment in wild bird surveillance and collaboration across interagency partners. IMPORTANCE: We present the results of Canada's Interagency Surveillance Program for Avian Influenza in Wild Birds in the year following the first detection of highly pathogenic avian influenza virus (HPAIV) H5N1 on the continent. The surveillance program tested over 17,000 wild birds, both sick and apparently healthy, which revealed spatiotemporal and taxonomic patterns in HPAIV prevalence and mortality across Canada. The significant shift in the presence and distribution of HPAIV in Canada's wild birds underscores the need for sustained investment in wild bird surveillance and collaboration across One Health partners.

Pathology and diagnosis of avian bornavirus infection in wild Canada geese (Branta canadensis), trumpeter swans (Cygnus buccinator) and mute swans (Cygnus olor) in Canada: a retrospective study.

Nine hundred and fifty-five pathology cases collected in Ontario between 1992 and 2011 from wild free-ranging Canada geese, trumpeter swans and mute swans were retrospectively evaluated for the pathology associated with avian bornavirus (ABV) infection. Cases were selected based on the presence of upper gastrointestinal impaction, central nervous system histopathology or clinical history suggestive of ABV infection. The proportion of birds meeting at least one of these criteria was significantly higher at the Toronto Zoo (30/132) than elsewhere in Ontario (21/823). Central, peripheral and autonomic nervous tissues were examined for the presence of lymphocytes and plasma cells on histopathology. The presence of virus was assessed by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) on frozen brains and on formalin-fixed paraffin-embedded tissues. Among selected cases, 86.3% (44/51) were considered positive on histopathology, 56.8% (29/51) were positive by immunohistochemistry, and RT-PCR was positive on 88.2% (15/17) of the frozen brains and 78.4% (40/51) of the formalin-fixed paraffin-embedded samples. Histopathological lesions included gliosis and lymphoplasmacytic perivascular cuffing in brain (97.7%), spinal cord (50%), peripheral nerves (55.5%) and myenteric ganglia or nerves (62.8%), resembling lesions described in parrots affected with proventricular dilatation disease. Partial amino acid sequences of the nucleocapsid gene from seven geese were 100% identical amongst themselves and 98.1 to 100% identical to the waterfowl sequences recently described in the USA. Although ABV has been identified in apparently healthy geese, our study confirmed that ABV can also be associated with significant disease in wild waterfowl species.

A 4-year study of avian influenza virus prevalence and subtype diversity in ducks of Newfoundland, Canada.

The island of Newfoundland, Canada, is at the eastern edge of North America and has migratory bird connections with the continental mainland as well as across the North Atlantic Ocean. Here, we report a 4-year avian influenza virus (AIV) epidemiological study in ducks in the St. John's region of Newfoundland. The overall prevalence of AIV detection in ducks during this study was 7.2%, with American Black Ducks contributing the vast majority of the collected samples and the AIV positives. The juvenile ducks showed a significantly higher AIV detection rate (10.6%) compared with adults (3.4%). Seasonally, AIV prevalence rates were higher in the autumn (8.4%), but positives were still detected in the winter (4.6%). Preliminary serology tests showed a high incidence of previous AIV infection (20/38, 52.6%). A total of 43 viruses were characterized for their HA-NA or HA subtypes, which revealed a large diversity of AIV subtypes and little recurrence of subtypes from year to year. Investigation of the movement patterns of ducks in this region showed that it is a largely non-migratory duck population, which may contribute to the observed pattern of high AIV subtype turnover. Phylogenetic analysis of 4 H1N1 and one H5N4 AIVs showed these viruses were highly similar to other low pathogenic AIV sequences from waterfowl in North America and assigned all gene segments into American-avian clades. Notably, the H1N1 viruses, which were identified in consecutive years, possessed homologous genomes. Such detection of homologous AIV genomes across years is rare, but indicates the role of the environmental reservoir in viral perpetuation.

CANINE DISTEMPER VIRUS ECOLOGY: INSIGHTS FROM A LONGITUDINAL SEROLOGIC STUDY IN WILD RACCOONS (PROCYON LOTOR).

Increasing reports of canine distemper virus (CDV) in a variety of hosts, and changing CDV dynamics, have led to renewed interest in the ecology of CDV infections in wildlife. Longitudinal serologic studies provide insights into intrapopulation and intraindividual pathogen dynamics, but few studies in wildlife have been conducted. We used data from 235 raccoons (Procyon lotor) captured on more than one occasion between May 2011 and November 2013 to investigate CDV dynamics in Ontario, Canada. Using mixed multivariable logistic regression, we found that juvenile raccoons were more likely to be seronegative from August to November than from May to July. Using paired titers from CDV-exposed individual raccoons, we determined that the winter breeding season, when there is high intraspecific contact and an increase in susceptible juveniles, may be a period of high risk for CDV exposure. Interestingly, CDV seropositive adult raccoons had nondetectable titers ranging from 1 mo to 1 yr later. Based on our preliminary investigation using two different statistical approaches, CDV exposure was associated with a decrease in parvovirus titer. This result raises important questions about whether virus-induced immune amnesia occurs after CDV exposure, which has been described for measles virus, a closely related pathogen. Overall, our results provide significant insights into CDV dynamics. Further research is needed to investigate whether CDV-induced immune amnesia occurs in raccoons and to determine the potential impacts of a reduced population immunity that may occur secondary to CDV exposure, particularly as it relates to rabies control efforts.

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.