ETIDIOH - NEW

  Abstract Influenza A virus (IAV) can infect a wide range of hosts, including wild and domestic pigs . Swine play an important role in influenza evolution and epidemiology due to their ability to get infected with both avian and human influenza viruses, potentially leading to reassorted virus variants . Interactions at the wild-domestic swine interface have been documented on multiple occasions, raising concern about pathogen transmission and the emergence of novel influenza strains. This study investigates the occurrence and subtypes of IAV infecting invasive wild pigs in Alberta, Canada . A total of 267 wild pigs were captured between 2021–2024. Exposure to IAV was initially detected by cELISA , with further confirmation of exposure to the H5Nx virus by hemagglutination inhibition (HI) and virus neutralization (VN) assays. Although no IAV genetic material was detected by qPCR , the seropositive samples by cELISA (4.17%; 5/120) coincided with the 2022–2024 highly pathogenic avian...

  Abstract Background :  Avian influenza of the H5N1 subtype shares substantial relatedness in its neuraminidase (NA) surface protein with human influenza A H1N1 viruses of the past century. Understanding variation in pre-existing anti-N1 antibodies against H5N1 is critical to pandemic risk assessment and preparedness.  Methods :  We used anonymized, residual sera collected equally from ten age groups spanning one to >80 years during an August 2024 cross-sectional serosurvey in British Columbia, Canada . We assessed NA inhibition antibody titres by enzyme-linked lectin assay against H5N1 (N=575), H1N1pdm09 (N=250) and H3N2 (N=205). We compared anti-NA titres by birth (imprinting) cohorts defined in relation to historic N1 and/or N2 exposure opportunities.  Results :  Among participants with median age 32 (IQR: 15-62) years, 404 ( 70%) had cross-reactive anti-N1 titre ≥10 against H5N1 , with 260 (45%), 182 (32%) and 98 (17%), having titres ≥40, ≥80 and ≥...

Abstract Since late 2021, a panzootic of highly pathogenic H5N1 avian influenza virus has driven significant morbidity and mortality in wild birds, domestic poultry, and mammals. In North America , infections in novel avian and mammalian species suggest the potential for changing ecology and establishment of new animal reservoirs . Outbreaks among domestic birds have persisted despite aggressive culling, necessitating a re-examination of how these outbreaks were sparked and maintained. To recover how these viruses were introduced and disseminated in North America, we analyzed 1,818 Hemagglutinin (HA) gene sequences sampled from North American wild birds, domestic birds and mammals from November 2021-September 2023 using Bayesian phylodynamic approaches. Using HA, we infer that the North American panzootic was driven by ~8 independent introductions into North America via the Atlantic and Pacific Flyways, followed by rapid dissemination westward via wild, migratory birds. Transmission wa...

Abstract Seasonal respiratory viruses, such as the Influenza A virus and the respiratory syncytial virus, are responsible for over a billion infections worldwide each year resulting in a substantial burden on health care systems . Surveillance of these viruses, including their prevalence in communities and their evolution , are essential for informing public health decisions and recommending vaccine formulations and schedules. Typically, these viruses are monitored using clinical samples from patients seeking medical attention. Recently, wastewater-based surveillance (WBS) has been leveraged to understand transmission dynamics and genome evolution of SARS-CoV-2 and seasonal respiratory viruses. To further the utility of WBS we developed and implemented novel tiled-amplicon sequencing assays to identify and track Influenza A virus H3N2 and respiratory syncytial virus A circulating in Southern Ontario, Canada . We also developed virus specific deconvolution tools to estimate the abundanc...

Abstract The November 2021 introduction of highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b into North America triggered a devastating outbreak , affecting more than 180 million domestic birds and spreading to more than 80 wildlife species across Canada and the US . From this outbreak, we have sequenced 2955 complete A( H5N1 ) viral genomes from samples collected in Canada and, in conjunction with previously published data, performed multifaceted phylodynamic analyses. These analyses reveal extensive diversification of A(H5N1) viruses via reassortment with low-pathogenic avian influenza viruses. We find evidence of repeated ancestral strain replacement by direct descendants, indicative of compounding viral fitness increases . Spatiotemporal modeling identified critical geographic areas facilitating transcontinental spread and demonstrated genotype-specific host dynamics, offering essential data for ongoing control and prevention strategies. Source: Science Advances,  https:...

Abstract We characterized highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b genotype D1.1 in wild birds and a human in British Columbia, Canada, during 2024. D1.1, the predominant genotype circulating in fall 2024, is a reassortment between Eurasian A3 lineage viruses , introduced to North America in 2022, and North American lineage viruses. Source: US Centers for Disease Control and Prevention,  https://wwwnc.cdc.gov/eid/article/31/6/24-1862_article ____

{Excerpt} Situation at a glance As of 18 April 2025, a total of 2318 measles cases , including three deaths , have been confirmed in six countries in the WHO Region of the Americas , an 11-fold increase compared to the same period in 2024 .  The majority of cases have occurred among people between 1 to 29 years , who are either unvaccinated or have an unknown vaccination status .  Additionally, most cases are imported or linked to importation.  Measles is a highly contagious, airborne viral disease that can lead to severe complications and death.  Although it is preventable with two doses of the vaccine, over 22 million children worldwide did not receive their first dose of the vaccine in 2023. This has contributed to a global rise in measles cases in 2024, which heightens the risk of imported infections, particularly from unvaccinated travellers arriving from areas where the virus is actively circulating.  WHO is working closely with countries in the WHO Region...

Abstract We report the detection of a clade 2.3.4.4b A(H5N1) reassortant virus with a neuraminidase surface protein derived from a North American lineage low-pathogenic avian influenza virus. This virus caused a widespread and ongoing outbreak across 45 poultry farms in British Columbia, Canada . Isolates from 8 farms reveal a mutation in the neuraminidase protein (H275Y) that is exceptionally rare among clade 2.3.4.4b viruses (present in 0.045% of publicly available clade 2.3.4.4b isolates). NA-H275Y is a well-known marker of resistance to the neuraminidase inhibitor oseltamivir . We demonstrate that this substitution maintains its resistance phenotype on the genetic background of H5N1 clade 2.3.4.4b viruses. Source: Emerging Microbes and Infections,  https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2469643 ____

On January 24, 2025 , the Canadian Food Inspection Agency (CFIA) was notified of mortality in a non-commercial backyard layer poultry farm in Newfoundland and Labrador. The CFIA National Centre for Foreign Animal Disease has confirmed on February 12, 2025 that the virus was H5N5 . The HA of the H5 virus from the samples belongs to Eurasian Gs/GD lineage HPAI H5N1 (2.3.4.4b) with cleavage site motif of “PLREKRRKR/GLF”, compatible with HPAI viruses. The sample contained AI virus similar to European like - H5N5 (2023) viruses which came to Canada via the Atlantic flyway . The viruses contained wholly Eurasian H5N5 genome segments . The CFIA has immediately quarantined the IP and is implementing strict movement controls and a stamping out policy. Primary control zone (PCZ) has been put in place around the IP. Surveillance is ongoing in the affected areas. WOAH data on poultry and non-poultry can be visualized and extracted on the AI dashboard in domestic birds available at https://cahss.ca...

Abstract Following reports of HPAI H5N1 infections of dairy cattle in the United States (US) in March 2024, we established a Pan-Canadian Milk network to monitor retail milk in Canada. Milk samples from across Canada that had previously tested negative for influenza A virus (IAV) RNA were tested for the presence of anti-IAV nucleoprotein (NP) antibodies , as an indicator of past infection of dairy cattle. None of the 109 milk samples tested had evidence of anti-IAV NP antibodies. This is consistent with previous findings from our academic group as well as others including federal testing initiatives that have not found any IAV RNA in milk. Although not surprising given that no cases of H5N1 in cattle have been reported in Canada to date, this work further supports that the extensive outbreak in dairy cattle in the US has not extended northward into Canada, and the integrity of the Canadian milk supply remains intact. Source: MedRxIV,  https://www.medrxiv.org/content/10.1101/2025.01...

Abstract Senecavirus A (SVA) continues to cause vesicular lesions in swine in Canada and many regions worldwide. Since the vesicular lesions caused by SVA are similar to those caused by foot and mouth disease virus , swine vesicular disease virus and vesicular stomatitis virus, a foreign animal disease investigation must be initiated to rule out these diseases. SVA isolates from pigs displaying vesicular lesions in Canada from 2015 to 2023 were sequenced, and phylogeographic analysis was performed using the complete genome sequences. The results infer that SVA has spread between the United States and Canada several times. In addition, the results suggest that SVA spreads from different regions. SVA spread was inferred from Canada into Thailand, India and Mexico and inferred from the United States to Brazil, Columbia, Chile and China with ten separate introductions. Furthermore, recombination was observed in SVA genomes from Canada, the United States and China. Source: Viruses,  htt...

To the Editor : Highly pathogenic avian influenza A(H5N1) viruses are circulating among wild birds and poultry in British Columbia, Canada .1 These viruses are also recognized to cause illness in humans . Here, we report a case of critical illness caused by influenza A(H5N1) virus infection in British Columbia. On November 4, 2024, a 13-year-old girl with a history of mild asthma and an elevated body-mass index (the weight in kilograms divided by the square of the height in meters) of greater than 35 presented to an emergency department in British Columbia with a 2-day history of conjunctivitis in both eyes and a 1-day history of fever . She was discharged home without treatment, but cough, vomiting, and diarrhea then developed, and she returned to the emergency department on November 7 in respiratory distress with hemodynamic instability. On November 8, she was transferred, while receiving bilevel positive airway pressure, to the pediatric intensive care unit at British Columbia Child...

Abstract Wild birds are important hosts of influenza A viruses (IAVs) and play an important role in their ecology. The emergence of the A/goose/Guangdong/1/1996 H5N1 (Gs/GD) lineage marked a shift in IAV ecology, leading to recurrent outbreaks and mortality in wild birds from 2002 onwards. This lineage has evolved and diversified over time, with a recent important derivative being the 2.3.4.4b sub-lineage, which has caused significant mortality events in wild bird populations. An H5N1 clade 2.3.4.4b virus was transmitted into North America from Eurasia in 2021, with the first detection being in Newfoundland and Labrador in Atlantic Canada , and this virus and its reassortants then spread broadly throughout North America and beyond. Following the first 2021 detection, there have been three additional known incursions of Eurasian-origin strains into Atlantic Canada, a second H5N1 strain in 2022 and two H5N5 strains in 2023 . In this study, we document a fifth incursion in Atlantic Canada...

Abstract Since late 2021, a panzootic of highly pathogenic H5N1 avian influenza virus has driven significant morbidity and mortality in wild birds, domestic poultry, and mammals. In North America , infections in novel avian and mammalian species suggest the potential for changing ecology and establishment of new animal reservoirs . Outbreaks among domestic birds have persisted despite aggressive culling, necessitating a re-examination of how these outbreaks were sparked and maintained. To recover how these viruses were introduced and disseminated in North America, we analyzed 1,818 Hemagglutinin (HA) gene sequences sampled from North American wild birds, domestic birds and mammals from November 2021-September 2023 using Bayesian phylodynamic approaches. Using HA, we infer that the North American panzootic was driven by ~8 independent introductions into North America via the Atlantic and Pacific Flyways , followed by rapid dissemination westward via wild, migratory birds. Transmission w...