Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Virus in Seals, St. Lawrence Estuary, Quebec, Canada1.

We describe an unusual mortality event caused by a highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b involving harbor (Phoca vitulina) and gray (Halichoerus grypus) seals in the St. Lawrence Estuary, Quebec, Canada, in 2022. Fifteen (56%) of the seals submitted for necropsy were considered to be fatally infected by HPAI H5N1 containing fully Eurasian or Eurasian/North American genome constellations. Concurrently, presence of large numbers of bird carcasses infected with HPAI H5N1 at seal haul-out sites most likely contributed to the spillover of infection to the seals. Histologic changes included meningoencephalitis (100%), fibrinosuppurative alveolitis, and multiorgan acute necrotizing inflammation. This report of fatal HPAI H5N1 infection in pinnipeds in Canada raises concerns about the expanding host of this virus, the potential for the establishment of a marine mammal reservoir, and the public health risks associated with spillover to mammals.Nous décrivons un événement de mortalité inhabituelle causé par un virus de l'influenza aviaire hautement pathogène A(H5N1) clade 2.3.4.4b chez des phoques communs (Phoca vitulina) et gris (Halichoerus grypus) dans l'estuaire du Saint-Laurent au Québec, Canada, en 2022. Quinze (56%) des phoques soumis pour nécropsie ont été considérés comme étant fatalement infectés par le virus H5N1 de lignées eurasiennes ou de réassortiment eurasiennes/nord-américaines. Un grand nombre simultané de carcasses d'oiseaux infectés par le H5N1 sur les sites d'échouement a probablement contribué à la contamination de ces phoques. Les changements histologiques associés à cette infection incluaient : méningo-encéphalite (100%), alvéolite fibrinosuppurée et inflammation nécrosante aiguë multi-organique. Cette documentation soulève des préoccupations quant à l'émergence de virus mortels, à la possibilité d'établissement de réservoirs chez les mammifères marins, et aux risques pour la santé publique associés aux propagations du virus chez les mammifères.

Influenza A(H5N1) Virus Infections in 2 Free-Ranging Black Bears (Ursus americanus), Quebec, Canada.

Wholly Eurasian highly pathogenic avian influenza H5N1 clade 2.3.4.4b virus was isolated from 2 free-ranging black bears with meningoencephalitis in Quebec, Canada. We found that isolates from both animals had the D701N mutation in the polymerase basic 2 gene, previously known to promote adaptation of H5N1 viruses to mammal hosts.

Isolation and Characterization of Novel Reassortant Influenza A(H10N7) Virus in a Harbor Seal, British Columbia, Canada.

We isolated a novel reassortant influenza A(H10N7) virus from a harbor seal in British Columbia, Canada, that died from bronchointerstitial pneumonia. The virus had unique genome constellations involving lineages from North America and Eurasia and polymerase basic 2 segment D701N mutation, associated with adaptation to mammals.

Outbreak of Rabbit Hemorrhagic Disease Virus 2 Infections, Ghana.

In September 2019, high mortality in commercial rabbits was reported in the Greater Accra Region of Ghana. Rabbit hemorrhagic disease virus 2 phylogenetically related to isolates from 2015-2017 outbreaks in the Netherlands was confirmed as the causative agent. The virus has not yet been detected in native rabbits in Ghana.

Drug related problems in admitted geriatric patients: the impact of clinical pharmacist interventions.

BACKGROUND: Geriatric patients are at high risk of Drug Related Problems (DRPs) due to multi- morbidity associated polypharmacy, age related physiologic changes, pharmacokinetic and pharmacodynamics alterations. These patients often excluded from premarketing trials that can further increase the occurrence of DRPs. This study aimed to identify drug related problems and determinants in geriatric patients admitted to medical and surgical wards, and to evaluate the impact of clinical pharmacist interventions for treatment optimization. METHODS: A prospective interventional study was conducted among geriatric patients admitted to medical and surgical wards of Jimma University Medical Center from April to July 2017. Clinical pharmacists reviewed patients drug therapy, identified drug related problems and provided interventions. Data were analyzed by using SPSS statistical software version 20.0. Descriptive statistics were performed to determine the proportion of drug related problems. Logistic regression analyses were performed to identify the determinants of drug related problems. RESULTS: A total of 200 geriatric patients were included in the study. The mean age of the participants was 67.3 years (SD7.3). About 82% of the patients had at least one drug related problems. A total of 380 drug related problems were identified and 670 interventions were provided. For the clinical pharmacist interventions, the prescriber acceptance rate was 91.7%. Significant determinants for drug related problems were polypharmacy (adjusted odds ratio [AOR] = 4.350, 95% C.I: 1.212-9.260, p = 0.020) and number of comorbidities (AOR = 1.588, 95% C.I: 1.029-2.450, p = 0.037). CONCLUSIONS: Drug related problems were substantially high among geriatric inpatients. Patients with polypharmacy and co-morbidities had a much higher chance of developing DRPs. Hence, special attention is needed to prevent the occurrence of DRPs in these patients. Moreover, clinical pharmacists' intervention was found to reduce DRPs in geriatric inpatients. The prescriber acceptance rate of clinical pharmacists' intervention was also substantially high.

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.

Highly Pathogenic Avian Influenza A(H7N9) Virus, Tennessee, USA, March 2017.

In March 2017, highly pathogenic avian influenza A(H7N9) was detected at 2 poultry farms in Tennessee, USA. Surveillance data and genetic analyses indicated multiple introductions of low pathogenicity avian influenza virus before mutation to high pathogenicity and interfarm transmission. Poultry surveillance should continue because low pathogenicity viruses circulate and spill over into commercial poultry.

Imbalance between innate antiviral and pro-inflammatory immune responses may contribute to different outcomes involving low- and highly pathogenic avian influenza H5N3 infections in chickens.

In order to gain further insight into the early virus-host interactions associated with highly pathogenic avian influenza virus infections in chickens, genome-wide expression profiling of chicken lung and brain was carried out at 24 and 72 h post-inoculation (h p.i.). For this purpose two recombinant H5N3 viruses were utilized, each possessing a polybasic HA0 cleavage site but differing in pathogenicity. The original rH5N3 P0 virus, which has a low-pathogenic phenotype, was passaged six times through chickens to give rise to the derivative rH5N3 P6 virus, which is highly pathogenic (Diederich S, Berhane Y, Embury-Hyatt C, Hisanaga T, Handel K et al.J Virol 2015;89:10724-10734). The gene-expression profiles in lung were similar for both viruses, although they varied in magnitude. While both viruses produced systemic infections, differences in clinical disease progression and viral tissue loads, particularly in brain, where loads of rH5N3 P6 were three orders of magnitude higher than rH5N3 P0 at 72 .p.i., were observed. Although genes associated with gene ontology (GO) categories INFα and INFß biosynthesis, regulation of innate immune response, response to exogenous dsRNA, defence response to virus, positive regulation of NF-κB import into the nucleus and positive regulation of immune response were up-regulated in rH5N3 P0 and rH5N3 P6 brains, fold changes were higher for rH5N3 P6. The additional up-regulation of genes associated with cytokine production, inflammasome and leukocyte activation, and cell-cell adhesion detected in rH5N3 P6 versus rH5N3 P0 brains, suggested that the balance between antiviral and pro-inflammatory innate immune responses leading to acute CNS inflammation might explain the observed differences in pathogenicity.

Hemagglutinin-Neuraminidase Balance Influences the Virulence Phenotype of a Recombinant H5N3 Influenza A Virus Possessing a Polybasic HA0 Cleavage Site.

UNLABELLED: Although a polybasic HA0 cleavage site is considered the dominant virulence determinant for highly pathogenic avian influenza (HPAI) H5 and H7 viruses, naturally occurring virus isolates possessing a polybasic HA0 cleavage site have been identified that are low pathogenic in chickens. In this study, we generated a reassortant H5N3 virus that possessed the hemagglutinin (HA) gene from H5N1 HPAI A/swan/Germany/R65/2006 and the remaining gene segments from low pathogenic A/chicken/British Columbia/CN0006/2004 (H7N3). Despite possessing the HA0 cleavage site GERRRKKR/GLF, this rH5N3 virus exhibited a low pathogenic phenotype in chickens. Although rH5N3-inoculated birds replicated and shed virus and seroconverted, transmission to naive contacts did not occur. To determine whether this virus could evolve into a HPAI form, it underwent six serial passages in chickens. A progressive increase in virulence was observed with the virus from passage number six being highly transmissible. Whole-genome sequencing demonstrated the fixation of 12 nonsynonymous mutations involving all eight gene segments during passaging. One of these involved the catalytic site of the neuraminidase (NA; R293K) and is associated with decreased neuraminidase activity and resistance to oseltamivir. Although introducing the R293K mutation into the original low-pathogenicity rH5N3 increased its virulence, transmission to naive contact birds was inefficient, suggesting that one or more of the remaining changes that had accumulated in the passage number six virus also play an important role in transmissibility. Our findings show that the functional linkage and balance between HA and NA proteins contributes to expression of the HPAI phenotype. IMPORTANCE: To date, the contribution that hemagglutinin-neuraminidase balance can have on the expression of a highly pathogenic avian influenza virus phenotype has not been thoroughly examined. Reassortment, which can result in new hemagglutinin-neuraminidase combinations, may have unpredictable effects on virulence and transmission characteristics of a virus. Our data show the importance of the neuraminidase in complementing a polybasic HA0 cleavage site. Furthermore, it demonstrates that adaptive changes selected for during the course of virus evolution can result in unexpected traits such as antiviral drug resistance.

Antimicrobial Use-Related Problems Among Hospitalized Pediatric Patients: A Prospective Observational Study.

Introduction: Antimicrobials are among the most commonly misused medications, leading to antimicrobial resistance, and therefore demand more attention. There are limited studies documenting "antimicrobial use-related problems" in developing countries, especially in pediatric patients. Objectives: This study aimed to evaluate the prevalence of antimicrobial use-related problems and risk factors among hospitalized pediatric patients. Materials and Methods: A hospital-based prospective observational study was conducted in Ayder comprehensive specialized hospital (ACSH) in the Tigray region, Ethiopia. The participants of the study were pediatric patients aged ≤15 years who were admitted with a diagnosis of infectious disease between September 2019 and November 2019. Results: A total of 232 pediatric patients were included in the study. Of these, 59.5% of the patients were male and the mean age (SD) of the patients was 5.8 (5.2) years. Of the 232 patients surveyed, a total of 177 antimicrobial use-related problems were identified. One or more antimicrobial use-related problems have occurred in more than half of the patients (53.9%). The commonest antimicrobial use problems were unnecessary antimicrobial therapy (22.8%) followed by need additional antimicrobial therapy (16.4%). In a multivariate logistic regression model, patients with comorbidities (Adjusted odds ratio (AOR): 1.84, 95% confidence interval (CI): 1.04-3.27) and hospital stays exceeding one week (AOR=1.88, 95% CI: 1.08-3.26) were predictors of antimicrobial use-related problems. Conclusion: Antimicrobial use-related problems were found in a significant proportion of pediatric patients. Addressing these issues necessitates collaborative efforts, emphasizing targeted education, strengthened antimicrobial stewardship, ensuring responsible antimicrobial use and enhancing pediatric care.

Patient Satisfaction with the Implementation of Telehealth in Ambulatory Care during the COVID-19 Pandemic: A Single Institution Experience.

Background: COVID-19 has reduced the capacity for delivering essential health services due to lockdown restrictions. Telehealth is an effective alternative option to improve healthcare access. However, there remain implementation challenges to patient adoption in resource-limited settings such as Ethiopia. Therefore, the purpose of this study was to assess patient satisfaction following the implementation of telehealth in ambulatory settings during the COVID-19 pandemic. Methods: A cross-sectional study was conducted at Ayder Comprehensive Specialized Hospital in the Tigray region of Northern Ethiopia. Patients who used the telehealth service were invited to participate in a patient satisfaction survey. All statistical analyses were performed using STATA Version 14.1. Result: A total of 149 patients have participated in the survey. Out of the total participants, 129 (86.6%) found that telehealth is easy to understand and overall satisfaction for telehealth was 87.9%. About two-thirds of the patients (97, 65.1%) reported that the telehealth visit is just as good as a traditional visit. The vast majority of participants (148, 98.6%) stated that they would definitely or probably use telehealth again and would recommend it to others. The majority of respondents (137, 91.9%) followed the recommendations provided. Conclusion: Patients have a high level of satisfaction with the use of telehealth during the COVID-19 pandemic. About two-thirds of patients said the telehealth visit was just as good as a traditional visit. The majority of patients followed the recommendations given to them by the healthcare providers and stated that they would definitely or probably use telehealth in the future and would recommend it to others. This high level of patient satisfaction with telehealth implementation suggests that the service could be considered in low-income countries as well.

Clinical and economic burden of healthcare-associated infections: A prospective cohort study.

INTRODUCTION: Healthcare-associated infections (HAIs) have become a serious public health problem. Despite the fact that implementing evidence-based infection control strategies could prevent HAIs and save billions of dollars, Ethiopia lacks national surveillance studies on the rate, economic, and clinical burden of HAIs. OBJECTIVE: To assess the clinical and economic burden of HAIs in hospitalized patients at Ayder comprehensive specialized hospital. MATERIALS AND METHODS: A prospective cohort study design was conducted in patients with and without HAIs. A review of medical records, interviews, and patient bills was used to extract necessary information. The patients in the two arms were matched based on age, sex, Charlson comorbidity index, and ward type. Measurable factors were compared between infected and uninfected patients using the paired ttest or McNemar's test, as appropriate. Logistic regression was used to identify predictors of in-hospital mortality. Stata 14.1 was used to conduct all analyses. RESULTS: A total of 408 patients, 204 with HAIs and 204 without HAIs were included in the study. In-hospital mortality was higher in patients with HAI (14.7% vs 7.8%, P = 0.028). Patients with HAI stayed an average of 8.3 days longer than controls (18.85 vs 10.59, P<0.001). The average direct medical costs for patients with HAI were 3033 Ethiopian birrs (ETB) higher than controls (4826 vs 1793, P<0.001). The presence of HAIs (AOR: 2.22, 95% CI: 1.13-4.39) and admission to intensive care units (AOR: 3.39, 95% CI: 1.55-7.40) were significant predictors of in-hospital mortality. CONCLUSION: HAIs have a significant impact on in-hospital mortality, the length of extra hospital stays, and extra costs for medical care. Patients admitted to intensive care units and those with HAIs were found to be significant predictors of in-hospital mortality. Interventions must be implemented to prevent HAIs, especially in patients admitted to intensive care units.

Second-Line Antiretroviral Treatment Outcomes and Predictors in Tigray Region, Ethiopia.

Introduction: Ethiopia has one of the highest HIV burdens in sub-Saharan Africa. Despite the fact that second-line antiretroviral therapy (ART) has been available for more than ten years, studies on its effectiveness are scarce. Objective: To assess treatment outcomes and predictors of unfavorable outcomes in HIV patients receiving second-line ART at Ayder Comprehensive Specialized Hospital and Mekelle Hospital. Materials and Methods: An institution-based retrospective cohort study was conducted in two hospitals in Tigray Region, Ethiopia. We evaluated 192 patients aged ≥15 years who were switched to second-line from November 2009 to May 2020 after failure of first-line ART. The primary outcome was the time from the initiation of second-line ART to the occurrence of unfavorable treatment outcomes (treatment failure, death, and loss to follow-up). We performed Kaplan-Meier survival estimates to calculate the cumulative incidence rates of unfavorable outcomes. Results: The mean age (SD) at the initiation of second-line ART was 39 (10.03) years, and the median CD4 cell count was 121 cells/microL. During a median follow-up of 4.6 years, 24 (12.5%) patients had died, 11 (5.7%) patients were lost to follow up, and 47 (24,4%) patients were experienced treatment failure. The incidence rates for unfavorable outcomes were 7.8 per 100 patients/years. Predictors for unfavorable outcomes were body mass index (BMI) <18.5 (adjusted hazard ratio [aHR] = 2.51, 95% confidence interval (CI): 1.27-4.95) and CD4 counts ≤100 cells/microL (aHR = 1.74, 95% CI: 1.09-2.79). Despite the failure of second-line ART, none of the patients received third-line ART. Conclusion: The incidence rate of unfavorable treatment outcomes for second-line ART was found to be high. A low BMI and a low baseline CD4 count were significant predictors of unfavourable outcomes and should be given special consideration in HIV care. A third-line ART regimen should also be considered for people who have failed second-line ART.

Recurring Trans-Atlantic Incursion of Clade 2.3.4.4b H5N1 Viruses by Long Distance Migratory Birds from Northern Europe to Canada in 2022/2023.

In December 2022 and January 2023, we isolated clade 2.3.4.4b H5N1 high-pathogenicity avian influenza (HPAI) viruses from six American crows (Corvus brachyrhynchos) from Prince Edward Island and a red fox (Vulpes vulpes) from Newfoundland, Canada. Using full-genome sequencing and phylogenetic analysis, these viruses were found to fall into two distinct phylogenetic clusters: one group containing H5N1 viruses that had been circulating in North and South America since late 2021, and the other one containing European H5N1 viruses reported in late 2022. The transatlantic re-introduction for the second time by pelagic/Icelandic bird migration via the same route used during the 2021 incursion of Eurasian origin H5N1 viruses into North America demonstrates that migratory birds continue to be the driving force for transcontinental dissemination of the virus. This new detection further demonstrates the continual long-term threat of H5N1 viruses for poultry and mammals and the subsequent impact on various wild bird populations wherever these viruses emerge. The continual emergence of clade 2.3.4.4b H5Nx viruses requires vigilant surveillance in wild birds, particularly in areas of the Americas, which lie within the migratory corridors for long-distance migratory birds originating from Europe and Asia. Although H5Nx viruses have been detected at higher rates in North America since 2021, a bidirectional flow of H5Nx genes of American origin viruses to Europe has never been reported. In the future, coordinated and systematic surveillance programs for HPAI viruses need to be launched between European and North American agencies.

Rapid evolution of A(H5N1) influenza viruses after intercontinental spread to North America.

Highly pathogenic avian influenza A(H5N1) viruses of clade 2.3.4.4b underwent an explosive geographic expansion in 2021 among wild birds and domestic poultry across Asia, Europe, and Africa. By the end of 2021, 2.3.4.4b viruses were detected in North America, signifying further intercontinental spread. Here we show that the western movement of clade 2.3.4.4b was quickly followed by reassortment with viruses circulating in wild birds in North America, resulting in the acquisition of different combinations of ribonucleoprotein genes. These reassortant A(H5N1) viruses are genotypically and phenotypically diverse, with many causing severe disease with dramatic neurologic involvement in mammals. The proclivity of the current A(H5N1) 2.3.4.4b virus lineage to reassort and target the central nervous system warrants concerted planning to combat the spread and evolution of the virus within the continent and to mitigate the impact of a potential influenza pandemic that could originate from similar A(H5N1) reassortants.

Characterization of neurotropic HPAI H5N1 viruses with novel genome constellations and mammalian adaptive mutations in free-living mesocarnivores in Canada.

The GsGd lineage (A/goose/Guangdong/1/1996) H5N1 virus was introduced to Canada in 2021/2022 through the Atlantic and East Asia-Australasia/Pacific flyways by migratory birds. This was followed by unprecedented outbreaks affecting domestic and wild birds, with spillover into other animals. Here, we report sporadic cases of H5N1 in 40 free-living mesocarnivore species such as red foxes, striped skunks, and mink in Canada. The clinical presentations of the disease in mesocarnivores were consistent with central nervous system infection. This was supported by the presence of microscopic lesions and the presence of abundant IAV antigen by immunohistochemistry. Some red foxes that survived clinical infection developed anti-H5N1 antibodies. Phylogenetically, the H5N1 viruses from the mesocarnivore species belonged to clade 2.3.4.4b and had four different genome constellation patterns. The first group of viruses had wholly Eurasian (EA) genome segments. The other three groups were reassortant viruses containing genome segments derived from both North American (NAm) and EA influenza A viruses. Almost 17 percent of the H5N1 viruses had mammalian adaptive mutations (E627 K, E627V and D701N) in the polymerase basic protein 2 (PB2) subunit of the RNA polymerase complex. Other mutations that may favour adaptation to mammalian hosts were also present in other internal gene segments. The detection of these critical mutations in a large number of mammals within short duration after virus introduction inevitably highlights the need for continually monitoring and assessing mammalian-origin H5N1 clade 2.3.4.4b viruses for adaptive mutations, which potentially can facilitate virus replication, horizontal transmission and posing pandemic risks for humans.

Characterization of H1N1 swine influenza viruses circulating in Canadian pigs in 2009.

The 2009 pandemic H1N1 (pH1N1), of apparent swine origin, may have evolved in pigs unnoticed because of insufficient surveillance. Consequently, the need for surveillance of influenza viruses circulating in pigs has received added attention. In this study we characterized H1N1 viruses isolated from Canadian pigs in 2009. Isolates from May 2009 were comprised of hemagglutinin and neuraminidase (NA) genes of classical SIV origin in combination with the North American triple-reassortant internal gene (TRIG) cassette, here termed contemporary SIV (conSIV) H1N1. These conSIV H1N1 viruses were contiguous with the North American αH1 cluster, which was distinct from the pH1N1 isolates that were antigenically more related to the γH1 cluster. After the initial isolation of pH1N1 from an Alberta pig farm in early May 2009, pH1N1 was found several times in Canadian pigs. These pH1N1 isolates were genetically and antigenically homogeneous. In addition, H1N1 viruses bearing seasonal human H1 and N1 genes together with the TRIG cassette and an NA encoding an oseltamivir-resistance marker were isolated from pigs. The NS gene of one of these seasonal human-like SIV (shSIV) H1N1 isolates was homologous to pH1N1 NS, implicating reassortment between the two strains. Antigenic cross-reactivity was observed between pH1N1 and conSIV but not with shSIV H1N1. In summary, although there was cocirculation of pH1N1 with conSIV and shSIV H1N1 in Canadian pigs after May 2009, there was no evidence supporting the presence of pH1N1 in pigs prior to May 2009. The possibility for further reassortants being generated exists and should be closely monitored.

Phylogenetic Inference of the 2022 Highly Pathogenic H7N3 Avian Influenza Outbreak in Northern Mexico.

The Mexican lineage H7N3 highly pathogenic avian influenza virus (HPAIV) has persisted in Mexican poultry since its first isolation in 2012. To date, the detection of this virus has gradually expanded from the initial one state to 18 states in Mexico. Despite the HPAIV H7N3 outbreak occurring yearly, the transmission pathways have never been studied, disallowing the establishment of effective control measures. We used a phylogenetic approach to unravel the transmission pathways of 2022 H7N3 HPAIVs in the new outbreak areas in Northern Mexico. We present genetic data of H7N3 viruses produced from 18 poultry farms infected in the spring of 2022. Our results indicate that the virus responsible for the current outbreak in Northern Mexico evolved from the Mexican lineage H7N3 HPAIV discovered in 2012. In the current outbreak, we identified five clusters of infection with four noticeably different genetic backgrounds. It is a cluster IV-like virus that was transmitted into one northern state causing an outbreak, then spreading to another neighboring northern state, possibly via a human-mediated mechanical transmission mechanism. The long-distance transmission event highlights the necessity for the more rigorous enforcement of biosafety measures in outbreaks. Additionally, we examined the evolutionary processes shaping the viral genetic and antigenic diversities. It is imperative to enhance active surveillance to include birds, the environment, and humans to detect HPAI in domestic poultry at an earlier point and eliminate it.

Evolutionary Dynamics of Mexican Lineage H5N2 Avian Influenza Viruses.

We have demonstrated for the first time a comprehensive evolutionary analysis of the Mexican lineage H5N2 avian influenza virus (AIV) using complete genome sequences (n = 189), from its first isolation in 1993 until 2019. Our study showed that the Mexican lineage H5N2 AIV originated from the North American wild bird gene pool viruses around 1990 and is currently circulating in poultry populations of Mexico, the Dominican Republic, and Taiwan. Since the implementation of vaccination in 1995, the highly pathogenic AIV (HPAIV) H5N2 virus was eradicated from Mexican poultry in mid-1995. However, the low pathogenic AIV (LPAIV) H5N2 virus has continued to circulate in domestic poultry populations in Mexico, eventually evolving into five distinct clades. In the current study, we demonstrate that the evolution of Mexican lineage H5N2 AIVs involves gene reassortments and mutations gained over time. The current circulating Mexican lineage H5N2 AIVs are classified as LPAIV based on the amino acid sequences of the hemagglutinin (HA) protein cleavage site motif as well as the results of the intravenous pathogenicity index (IVPI). The immune pressure from vaccinations most likely has played a significant role in the positive selection of antigenic drift mutants within the Mexican H5N2 AIVs. Most of the identified substitutions in these viruses are located on the critical antigenic residues of the HA protein and as a result, might have contributed to vaccine failures. This study highlights and stresses the need for vaccine updates while emphasizing the importance of continued molecular monitoring of the HA protein for its antigenic changes compared to the vaccines used.

A threat from both sides: Multiple introductions of genetically distinct H5 HPAI viruses into Canada via both East Asia-Australasia/Pacific and Atlantic flyways.

From 2016 to 2020, high pathogenicity avian influenza (HPAI) H5 viruses circulated in Asia, Europe, and Africa, causing waves of infections and the deaths of millions of wild and domestic birds and presenting a zoonotic risk. In late 2021, H5N1 HPAI viruses were isolated from poultry in Canada and also retrospectively from a great black-backed gull (Larus marinus), raising concerns that the spread of these viruses to North America was mediated by migratory wild bird populations. In February and April 2022, H5N1 HPAI viruses were isolated from a bald eagle (Haliaeetus leucocephalus) and broiler chickens in British Columbia, Canada. Phylogenetic analysis showed that the virus from bald eagle was genetically related to H5N1 HPAI virus isolated in Hokkaido, Japan, in January 2022. The virus identified from broiler chickens was a reassortant H5N1 HPAI virus with unique constellation genome segments containing PB2 and NP from North American lineage LPAI viruses, and the remaining gene segments were genetically related to the original Newfoundland-like H5N1 HPAI viruses detected in November and December 2021 in Canada. This is the first report of H5 HPAI viruses' introduction to North America from the Pacific and the North Atlantic-linked flyways and highlights the expanding risk of genetically distinct virus introductions from different geographical locations and the potential for local reassortment with both the American lineage LPAI viruses in wild birds and with both Asian-like and European-like H5 HPAI viruses. We also report the presence of some amino acid substitutions across each segment that might contribute to the replicative efficiency of these viruses in mammalian host, evade adaptive immunity, and pose a potential zoonotic risk.