Highly Pathogenic Avian Influenza Outbreaks Research Articles

Current status and future challenges of avian influenza – a literature review

An infectious agent affecting both domestic and wild birds may cause avian influenza. All of them can be transmitted by coming into contact with tainted food, drink, or bird emissions, particularly feces. Numerous clades of H5N1 infections have been circulating since 2003, including one introduced to the United States in 2014 by wild birds, which persisted until 2016. There were 2,240 wild birds found in 45 states and 519 counties in the United States alone by September 14, 2022. According to the World Organization for Animal Health (WOAH), the predominant Highly Pathogenic Avian Influenza (HPAI) A (H5) virus subtype causing poultry outbreaks worldwide from late 2021 to early 2022 is A (H5N1). Most notifications from wild birds across multiple countries and regions suggest that the virus may have been introduced and spread via uncontrolled bird migration. The primary instance of a goose/Guangdong/1/96-lineage H5 HPAI infection inside the Americas since June 2015 was checked by the later disclosure of an H5N1 HPAI outbreak in Newfoundland, Canada. The avian flu Type A viruses, or bird flu viruses, rarely cause human infection; some bird flu viruses have done so in the past. The HPAI (H5) virus has been persistent in wild bird populations in Europe since the 2020-21 epidemic wave, according to the paper titled “Avian Influenza Overview: March-June 2022.” Even regions like Antarctica had avian influenza cases in 2023-24. Prevention and control can be done by monitoring and reporting outbreaks, preventing avian influenza at its source in animals, banning chicken farms, controlling methodologies, remuneration for ranchers, and vaccination.

Blowflies are potential vector for avian influenza virus at enzootic area in Japan

High pathogenicity avian influenza (HPAI) poses a significant threat to both domestic and wild birds globally. The avian influenza virus, known for environmental contamination and subsequent oral infection in birds, necessitates careful consideration of alternative introduction routes during HPAI outbreaks. This study focuses on blowflies (genus Calliphora), in particular Calliphora nigribarbis, attracted to decaying animals and feces, which migrate to lowland areas of Japan from northern or mountainous regions in early winter, coinciding with HPAI season. Our investigation aims to delineate the role of blowflies as HPAI vectors by conducting a virus prevalence survey in a wild bird HPAI-enzootic area. In December 2022, 648 Calliphora nigribarbis were collected. Influenza virus RT-PCR testing identified 14 virus-positive samples (2.2% prevalence), with the highest occurrence observed near the crane colony (14.9%). Subtyping revealed the presence of H5N1 and HxN1 in some samples. Subsequent collections in December 2023 identified one HPAI virus-positive specimen from 608 collected flies in total, underscoring the potential involvement of blowflies in HPAI transmission. Our observations suggest C. nigribarbis may acquire the HPAI virus from deceased wild birds directly or from fecal materials from infected birds, highlighting the need to add blowflies as a target of HPAI vector control.

Re-evaluating efficacy of vaccines against highly pathogenic avian influenza virus in poultry: A systematic review and meta-analysis

The global spread of highly pathogenic avian influenza (HPAI) A (H5N1) clade 2.3.4.4b virus since 2021 necessitates a re-evaluation of the role of vaccination in controlling HPAI outbreaks among poultry, which has been controversial because of the concern of silent spread with viral mutation and spillover to human. We systematically reviewed and meta-analyzed all existing data from experimental challenge trials to assess the efficacy of HPAI vaccines against mortality in specific pathogen free (SPF) chickens, with evaluation of the certainty of evidence (CoE) using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Out of 223 screened publications, 46 trials met our eligibility criteria. Inactivated vaccines showed an efficacy of 95% (risk ratio [RR] = 5% [95% CI: 1% to 17%], I2 = 0%, CoE high) against homologous strains and an efficacy of 78% (RR = 22% [95% CI: 14% to 37%], I2 = 18%, CoE high) against heterologous strains (test for subgroup difference p = 0.02). Live recombinant vaccines exhibited the highest efficacy at 97% (RR = 3% [95% CI: 1% to 13%], I2 = 0%, CoE high). Inactivated recombinant vaccines had an overall efficacy of 90% (RR = 10% [95% CI: 6% to 16%], I2 = 47%, CoE high). Commercial vaccines showed an overall efficacy of 91% (RR = 9% [95% CI: 5% to 17%], I2 = 23%, CoE high), with 96% efficacy (RR = 4% [95% CI: 1% to 21%], I2 = 0%, CoE high) against homologous strains and 90% efficacy (RR = 10% [95% CI: 5% to 20%], I2 = 31%, CoE moderate) against heterologous strains. Our systematic review offers an updated and unbiased assessment of vaccine efficacy against HPAI-related mortality, providing timely and crucial information for re-evaluating the role of vaccination in poultry avian influenza control policy amist the global HPAI outbreak post-2021.

Avian influenza overview December 2023-March 2024.

Between 2 December 2023 and 15 March 2024, highly pathogenic avian influenza (HPAI) A(H5) outbreaks were reported in domestic (227) and wild (414) birds across 26 countries in Europe. Compared to previous years, although still widespread, the overall number of HPAI virus detections in birds was significantly lower, among other reasons, possibly due to some level of flock immunity in previously affected wild bird species, resulting in reduced contamination of the environment, and a different composition of circulating A(H5N1) genotypes. Most HPAI outbreaks reported in poultry were primary outbreaks following the introduction of the virus by wild birds. Outside Europe, the majority of outbreaks in poultry were still clustered in North America, while the spread of A(H5) to more naïve wild bird populations on mainland Antarctica is of particular concern. For mammals, A(H5N5) was reported for the first time in Europe, while goat kids in the United States of America represented the first natural A(H5N1) infection in ruminants. Since the last report and as of 12 March 2024, five human avian influenza A(H5N1) infections, including one death, three of which were clade 2.3.2.1c viruses, have been reported by Cambodia. China has reported two human infections, including one fatal case, with avian influenza A(H5N6), four human infections with avian influenza A(H9N2) and one fatal case with co-infection of seasonal influenza A(H3N2) and avian influenza A(H10N5). The latter case was the first documented human infection with avian influenza A(H10N5). Human infections with avian influenza remain rare and no sustained human-to-human infection has been observed. The risk of infection with currently circulating avian H5 influenza viruses of clade 2.3.4.4b in Europe remains low for the general population in the EU/EEA. The risk of infection remains low to moderate for those occupationally or otherwise exposed to infected animals.

Descriptive Epidemiology and Phylodynamics of the “First Wave” of an Outbreak of Highly Pathogenic Avian Influenza (H5N1 Clade 2.3.4.4b) in British Columbia and the Yukon, Canada, April to September 2022

Highly pathogenic avian influenza (HPAI) is a viral disease that causes significant rates of morbidity and mortality in domestic poultry and wild birds, with occasional spillover into mammals, including humans. Beginning in November 2021, Canada experienced its longest and largest outbreak of HPAI in history. A portion of this outbreak (H5N1, clade 2.3.4.4b) occurred in western Canada, specifically in British Columbia (B.C.) and the Yukon, between April 12 and September 11, 2022, which was classified as the “first wave” in this region. Wild birds and mammals identified through passive surveillance and suspect domestic poultry flocks were screened for avian influenza virus (AIV), typed H5 by qPCR, and positive cases were whole genome sequenced. Descriptive epidemiological and phylodynamic analyses were performed to: (1) understand the taxonomic and geographic extent of wild species involved; and (2) examine the origins and probable transmission networks of HPAI viruses introduced into B.C./Yukon by comparing local viruses with those circulating elsewhere in North America. This outbreak included 21 species of wild birds, 2 species of wild mammals, 4 commercial, and 12 domestic small flock infected premises. Canada geese (Branta canadensis) and bald eagles (Haliaeetus leucocephalus) were the most common wild species detected. We demonstrate that north-south avian migration via the Pacific Flyway is the probable route of multiple incursions into this region. Phylogenetic analysis of the hemagglutinin (HA) segment revealed that the B.C./Yukon viruses detected formed five distinct genetic clusters which were maintained across the whole genome. Although, the genome segments were predominantly Eurasian in origin, NP and PB2 segments from all samples, as well as NS and PB1 segments from Cluster 3, had North American origins. Overall, we demonstrate the utility of genomic epidemiology to inform HPAI transmission dynamics across Western Canada and discuss potential knowledge gaps that exist in passive surveillance strategies for HPAI.

Evolution and Spread of Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Wild Birds, South Korea, 2022-2023.

During October 2022-March 2023, highly pathogenic avian influenza (HPAI) A(H5N1) clade 2.3.4.4b virus caused outbreaks in South Korea, including 174 cases in wild birds. To understand the origin and role of wild birds in the evolution and spread of HPAI viruses, we sequenced 113 HPAI isolates from wild birds and performed phylogenetic analysis. We identified 16 different genotypes, indicating extensive genetic reassortment with viruses in wild birds. Phylodynamic analysis showed that the viruses were most likely introduced to the southern Gyeonggi-do/northern Chungcheongnam-do area through whooper swans (Cygnus cygnus) and spread southward. Cross-species transmission occurred between various wild bird species, including waterfowl and raptors, resulting in the persistence of HPAI in wild bird populations and further geographic spread as these birds migrated throughout South Korea. Enhanced genomic surveillance was an integral part of the HPAI outbreak response, aiding in timely understanding of the origin, evolution, and spread of the virus.

UK flockdown: A survey of smallscale poultry keepers and their understanding of governmental guidance on highly pathogenic avian influenza (HPAI)

The scale of the current outbreak of highly pathogenic avian influenza (HPAI) due to the A/H5N1 virus in the United Kingdom is unprecedented. In addition to its economic impact on the commercial poultry sector, the disease has devastated wild bird colonies and represents a potential public health concern on account of its zoonotic potential. Although the implementation of biosecurity measures is paramount to reducing the spread of HPAI in domestic and commercial settings, little is known about the attitudes and perspectives of backyard poultry keepers, who often keep their flocks in close proximity to the public. A large nationwide survey of backyard poultry keepers was undertaken in December 2021–March 2022, contemporaneous with the enforcement of an Avian Influenza Prevention Zone (AIPZ) and additional housing measures in England, Scotland and Wales. The survey explored keepers’ understanding of the clinical manifestations of HPAI, compliance with housing and biosecurity measures, attitudes towards obligatory culling on confirmation of HPAI in their flocks, and the potential use of vaccination to control HPAI. Summary statistical analysis of the closed question responses was supplemented with qualitative data analysis and corpus linguistic approaches to draw out key themes and salient patterns in responses to open text questions. Survey responses were received from 1559 small-scale poultry keepers across the United Kingdom. Awareness of the HPAI outbreak was very high (99.0%). The majority of respondents learned of it via social media (53%), with Defra (49.7%), British Hen Welfare Trust (33.8%) and the APHA (22.0%) identified as the principal sources of information. Analysis revealed that backyard keepers lacked knowledge of the clinical signs of avian influenza and legal requirements relating to compliance with biosecurity measures. Some respondents dismissed the seriousness of HPAI and were unwilling to comply with the measures in force. The issue of obligatory culling proved highly emotive, and some expressed a lack of trust in authorities. Most respondents (93.1%) indicated a willingness to pay for vaccination if the option was available. Communications on biosecurity measures that are relevant to large-scale industrial setups are inappropriate for backyard contexts. Understanding the barriers that backyard keepers face is essential if official agencies are to communicate biosecurity information effectively to such groups. Lack of trust in authorities is likely to make elimination of the virus in the UK difficult. We make recommendations for tailoring HPAI-related information for backyard contexts, to aid future HPAI control measures in the UK.

Probenecid Inhibits Influenza A(H5N1) and A(H7N9) Viruses In Vitro and in Mice.

Avian influenza (AI) viruses cause infection in birds and humans. Several H5N1 and H7N9 variants are highly pathogenic avian influenza (HPAI) viruses. H5N1 is a highly infectious bird virus infecting primarily poultry, but unlike other AIs, H5N1 also infects mammals and transmits to humans with a case fatality rate above 40%. Similarly, H7N9 can infect humans, with a case fatality rate of over 40%. Since 1996, there have been several HPAI outbreaks affecting humans, emphasizing the need for safe and effective antivirals. We show that probenecid potently inhibits H5N1 and H7N9 replication in prophylactically or therapeutically treated A549 cells and normal human broncho-epithelial (NHBE) cells, and H5N1 replication in VeroE6 cells and mice.

Veterinarians' knowledge and experience of avian influenza and perspectives on control measures in the UK.

The scale of the outbreak of highly pathogenic avian influenza (HPAI) in 2021-23 due to the influenza A/H5N1 virus is unprecedented. An online survey was designed to explore veterinarians' experiences of and confidence in treating avian species, experiences of dealing with suspected HPAI and perspectives on control measures in the UK. The survey ran between December 2021 and March 2022. Survey responses were received from 26 veterinarians. Although veterinarians are well placed to communicate HPAI-related information and guidance, a lack of confidence around treating birds and dealing with suspected cases of HPAI represent key barriers for non-specialist practices, and this limits opportunities to educate clients. This study presents the views of a small group of self-selected respondents and may over-represent veterinarians with existing interests in avian species and/or avian influenza and who engage with online fora. Improved training and resources designed to increase confidence with avian species, along with guidance on diagnosing and reporting notifiable diseases, are needed for first opinion practices. Governing bodies should clarify regulations on treating birds in veterinary practices when HPAI outbreak numbers are high.

Field and laboratory investigation of highly pathogenic avian influenza H5N6 and H5N8 in Quang Ninh province, Vietnam, 2020 to 2021.

Avian influenza (AI) is a contagious disease that causes illness and death in poultry and humans. High pathogenicity AI (HPAI) H5N6 outbreaks commonly occur in Quang Ninh province bordering China. In June 2021, the first HPAI H5N8 outbreak occurred at a Quang Ninh chicken farm. This study examined the risk factors associated with HPAI H5N6 and H5N8 outbreaks in Quang Ninh. A retrospective case-control study was conducted in Quang Ninh from Nov 2021 to Jan 2022. The cases were households with susceptible poultry with two or more clinical signs and tested positive by real-time reverse transcription polymerase chain reaction. The controls were households in the same village as the cases but did not show clinical symptoms of the disease. Logistic regression models were constructed to assess the risk factors associated with HPAI outbreaks at the household level. There were 38 cases with H5N6 clade 2.3.4.4h viruses (n = 35) and H5N8 clade 2.3.4.4b viruses (n = 3). Compared to the 112 controls, raising poultry in uncovered or partially covered ponds (odds ratio [OR], 7.52; 95% confidence interval [CI], 1.44-39.27), poultry traders visiting the farm (OR, 8.66; 95% CI, 2.7-27.69), farms with 50-2,000 birds (OR, 3.00; 95% CI, 1.06-8-51), and farms with ≥ 2,000 birds (OR, 11.35; 95% CI, 3.07-41.94) were significantly associated with HPAI outbreaks. Combining biosecurity measures, such as restricting visitor entry and vaccination in farms with more than 50 birds, can enhance the control and prevention of HPAI in Quang Ninh and its spread across borders.

Retrospective Study of Highly Pathogenic Avian Influenza Outbreaks from 2015 to 2022 in Rivers State, Nigeria

Objectives: Highly pathogenic avian influenza (HPAI) constitutes one of the major constraints in the development of the poultry industry, and sporadic outbreaks are still being reported in Nigeria. It is zoonotic, with several reports of human cases. The aim of this study was to determine the trend and distribution of HPAI outbreaks from 2015 to 2022 in Rivers State, Nigeria. Eight-year retrospective study was conducted by reviewing the Avian influenza (AI) line list and case reports of confirmed outbreaks of HPAI in Rivers State from the AI desk office. Material and Methods: Data were cleaned, analyzed using descriptive statistics, and presented using tables and figures as appropriate. Results: The outcomes showed that a total of 67 HPAI cases were reported in Rivers State from 2015 to 2022, with the highest (64.2%) reported in 2015 and lowest (1.5%) in 2022. Layers were majorly affected. The HPAI cases were reported across 6 Local Government Areas (LGAs), with the highest (71.6% cases) reported in Obio-Akpor and the lowest (1.5%) in Oyigbo and Ogba-Egbema-Ndoni LGAs. Based on the distribution according to LGA and year, HPAI cases were reported in 5 LGAs (Port Harcourt, Obio-Akpor, Ikwerre, Oyigbo and Ogba-Egbema-Ndoni) in 2015, 2 LGAs (Obio-Akpor and Ikwerre) in 2016, 4 LGAs (Port Harcourt, Obio-Akpor, Ikwerre and Okrika) in 2021, and 1 LGA (Obio-Akpor) in 2022. Conclusion: The 2015 – 2022 outbreaks of HPAI in Rivers State were reported in six out of the 23 LGAs across Rivers State. Obio-Akpor LGA accounted for the highest-burden of HPAI in the State. There was no report of HPAI from 2017 to 2022 across the State. Intensive surveillance for AI and public awareness on prevention and control across Rivers State is, therefore, recommended with support and motivation from the government.

Ecological drivers for poultry farms predisposed to highly pathogenic avian influenza virus infection during the initial phase of the six outbreaks between 2010-2021: a nationwide study in South Korea.

Highly pathogenic avian influenza (HPAI) has caused substantial economic losses worldwide. An understanding of the environmental drivers that contribute to spillover transmission from wild birds to poultry farms is important for predicting areas at risk of introduction and developing risk-based surveillance strategies. We conducted an epidemiological study using data from six HPAI outbreak events in South Korea. An aggregate-level study design was implemented using third-level administrative units in South Korea. Only regions with high natural reservoir suitability were included. The incidence of HPAI at chicken and duck farms during the initial phase (30 and 45 days after the first case) of each outbreak event was used as the outcome variable, assuming that cross-species transmission from wild birds was the dominant exposure leading to infection. Candidate environmental drivers were meteorological factors, including temperature, precipitation, humidity, and altitude, as well as the proportion of protected area, farm density, deforestation level, and predator species richness. Logistic regression models were implemented; conditional autoregression models were used in cases of spatial autocorrelation of residuals. Lower temperature, higher farm density, and lower predator species richness were significantly associated with a higher risk of HPAI infection on chicken farms. Lower temperature, higher proportion of protected area, and lower predator species richness were significantly associated with a higher risk of HPAI infection on duck farms. The predicted dominant transmission routes on chicken and duck farms were horizontal and spillover, respectively. These results reveal a potential protective effect of predator species richness against HPAI outbreaks. Further studies are required to confirm a causal relationship.

Avian influenza overview September-December 2023.

Between 2 September and 1 December 2023, highly pathogenic avian influenza (HPAI) A(H5) outbreaks were reported in domestic (88) and wild (175) birds across 23 countries in Europe. Compared to previous years, the increase in the number of HPAI virus detections in waterfowl has been delayed, possibly due to a later start of the autumn migration of several wild bird species. Common cranes were the most frequently affected species during this reporting period with mortality events being described in several European countries. Most HPAI outbreaks reported in poultry were primary outbreaks following the introduction of the virus by wild birds, with the exception of Hungary, where two clusters involving secondary spread occurred. HPAI viruses identified in Europe belonged to eleven different genotypes, seven of which were new. With regard to mammals, the serological survey conducted in all fur farms in Finland revealed 29 additional serologically positive farms during this reporting period. Wild mammals continued to be affected mostly in the Americas, from where further spread into wild birds and mammals in the Antarctic region was described for the first time. Since the last report and as of 1 December 2023, three fatal and one severe human A(H5N1) infection with clade 2.3.2.1c viruses have been reported by Cambodia, and one A(H9N2) infection was reported from China. No human infections related to the avian influenza detections in animals in fur farms in Finland have been reported, and human infections with avian influenza remain a rare event. The risk of infection with currently circulating avian H5 influenza viruses of clade 2.3.4.4b in Europe remains low for the general population in the EU/EEA. The risk of infection remains low to moderate for occupationally or otherwise exposed people to infected birds or mammals (wild or domesticated); this assessment covers different situations that depend on the level of exposure.

Experimental Infection of Chickens with H5N8 High Pathogenicity Avian Influenza Viruses Isolated in Japan in the Winter of 2020-2021.

During the winter of 2020-2021, numerous outbreaks of high pathogenicity avian influenza (HPAI) were caused by viruses of the subtype H5N8 in poultry over a wide region in Japan. The virus can be divided into five genotypes-E1, E2, E3, E5, and E7. The major genotype responsible for the outbreaks was E3, followed by E2. To investigate the cause of these outbreaks, we experimentally infected chickens with five representative strains of each genotype. We found that the 50% chicken infectious dose differed by up to 75 times among the five strains, and the titer of the E3 strains (102.75 50% egg infectious dose (EID50)) was the lowest, followed by that of the E2 strains (103.50 EID50). In viral transmission experiments, in addition to the E3 and E2 strains, the E5 strain was transmitted to naïve chickens with high efficiency (>80%), whereas the other strains had low efficiencies (<20%). We observed a clear difference in the virological characteristics among the five strains isolated in the same season. The higher infectivity of the E3 and E2 viruses in chickens may have caused the large number of HPAI outbreaks in Japan during this season.

Avian influenza and the Brazilian poultry production: Current situation and prevention strategies

Highly Pathogenic Avian Influenza (HPAI) presents a significant threat to global poultry, affecting trade and consumer trust. This analysis focuses on Brazil's preventive measures against HPAI to uphold its disease-free status recognized by the World Organization for Animal Health (WOAH). As of September 19th, 2023, Brazil confirmed 106 HPAI outbreaks, primarily in wild birds, with a few in backyard chickens. Despite most incidents occurring along the coast, a notable outbreak in Bonito-MS underlines the necessity for ongoing vigilance in key poultry regions. Brazil's HPAI prevention framework, initiated with the 1994 National Poultry Health Plan, has continually evolved. High biosecurity measures are emphasized in stringent regulations, surveillance, and rapid response strategies. The nation's vertically integrated poultry model supports centralized control, traceability, and consistent quality, fostering swift corrective actions and biosecurity guidelines. The private sector's commitment complements these efforts, often exceeding government regulations with rigorous biosecurity practices, highlighting Brazil's holistic approach to safeguarding its poultry sector from HPAI threats.

Avian influenza overview June-September 2023.

Between 24 June and 1 September 2023, highly pathogenic avian influenza (HPAI) A(H5) outbreaks were reported in domestic (25) and wild (482) birds across 21 countries in Europe. Most of these outbreaks appeared to be clustered along coastlines with only few HPAI virus detections inland. In poultry, all HPAI outbreaks were primary and sporadic with most of them occurring in the United Kingdom. In wild birds, colony-breeding seabirds continued to be most heavily affected, but an increasing number of HPAI virus detections in waterfowl is expected in the coming weeks. The current epidemic in wild birds has already surpassed the one of the previous epidemiological year in terms of total number of HPAI virus detections. As regards mammals, A(H5N1) virus was identified in 26 fur animal farms in Finland. Affected species included American mink, red and Arctic fox, and common raccoon dog. The most likely source of introduction was contact with gulls. Wild mammals continued to be affected worldwide, mostly red foxes and different seal species. Since the last report and as of 28 September 2023, two A(H5N1) clade 2.3.4.4b virus detections in humans have been reported by the United Kingdom, and three human infections with A(H5N6) and two with A(H9N2) were reported from China, respectively. No human infection related to the avian influenza detections in animals on fur farms in Finland or in cats in Poland have been reported, and human infections with avian influenza remain a rare event. The risk of infection with currently circulating avian H5 influenza viruses of clade 2.3.4.4b in Europe remains low for the general population in the EU/EEA. The risk of infection remains low to moderate for occupationally or otherwise exposed people to infected birds or mammals (wild or domesticated); this assessment covers different situations that depend on the level of exposure.

Avian influenza and Brazilian poultry production – Current situation and prevention strategies. Proceeding of The First International Avian Influenza Summit, University of Arkansas- October 16-17, 2023"

Highly Pathogenic Avian Influenza (HPAI), particularly caused by the influenza virus A genus, is a paramount concern for global poultry health. The strains associated with HPAI are known to precipitate mortality rates exceeding 90\%. Beyond the immediate and catastrophic impact on poultry, the emergence of HPAI strains disrupts international poultry trade, leading countries to impose trade bans and shake consumer confidence. By September 19th, 2023, Brazil had reported 106 confirmed outbreaks of HPAI. Most of these incidents were linked to wild birds, totaling 103 cases, while backyard chickens accounted for the remaining three. Notably, most of these outbreaks are situated in coastal regions. However, an exception that demanded attention was the HPAI detection in backyard chickens in Bonito, Mato Grosso do Sul. State-wise analysis reveals differential prevalence patterns. São Paulo and Rio Grande do Sul have documented cases far from their primary poultry hubs. In juxtaposition, Espírito Santo's proximity to the outbreak areas heightens its risk profile. The southern broiler-producing regions, which account for a significant 64\% of Brazil's total production and a whopping 79\% of exports, currently face diminished immediate threats due to their inland geographies. Nevertheless, the episode in Bonito-MS underscores the escalating risks even in regions previously considered low-threat and amplifies the call for perpetual vigilance. Brazil's approach to HPAI defense is structured and well-planned, not a result of hasty improvisation or last-minute measures. It's a result of a long-standing commitment and rigorous planning. The country's legal framework for HPAI prevention has evolved since the 1994 introduction of the National Poultry Health Plan. Successive years saw further tightening of regulations, climaxing with the 2013 National Contingency Plan for Avian Influenza, which underwent revision in 2023. Brazil’s strategy to ward off HPAI is deeply rooted in stringent biosecurity measures. Farms are mandated to erect physical barriers, strictly regulate vehicular and human movement, and uphold rigorous cleaning and disinfection standards. Farm personnel are also trained in and adhere to meticulous personal hygiene protocols. Simultaneously, comprehensive waste management practices are firmly in place. Additionally, the Brazilian government plays a proactive role. Border surveillance, active monitoring of avian populations, and the deployment of passive surveillance within commercial flocks manifest the government's unwavering dedication to the poultry sector. One of Brazil's trump cards against diseases like HPAI is its vertically integrated poultry production model. This modus operandi permits companies and cooperatives to oversee every production stage. Such centralized oversight minimizes financial risks, guarantees consistent quality, and facilitates the swift roll-out of biosecurity directives. Traceability, a cornerstone for rapid disease containment, is inherently assured in this system. The private sector in Brazil not only meets governmental biosecurity standards but frequently surpasses them. It's common to see the integration of extended quarantine durations, intensified disinfection routines, and stringent farm access controls. The commitment to a tiered biosecurity mechanism across diverse poultry production stages is a testament to the industry's intent to ensure a holistic health foundation. Brazil's comprehensive and adaptive approach to HPAI is commendable. The country's strategic alignment between governmental regulations and private sector commitment, especially in the face of recent outbreaks, underscores Brazil's unwavering focus on safeguarding its poultry industry. While the road ahead demands continuous vigilance, Brazil's current strategies and learnings provide valuable insights for global stakeholders.

Vaccination against highly pathogenic avian influenza (HPAI): From opposition to acceptance. Proceeding of The First International Avian Influenza Summit, University of Arkansas- October 16-17, 2023”

The emergence of Highly Pathogenic Avian Influenza (HPAI) strains poses a significant threat to both avian populations and human health. Vaccination has been identified as a critical tool in mitigating the spread of HPAI. However, the acceptance and implementation of avian influenza vaccination programs have been met with opposition from various stakeholders, including poultry producers, public health authorities, and consumers. This abstract provides a comprehensive overview of the evolving landscape of HPAI vaccination strategies, tracing the trajectory from initial resistance to widespread acceptance. Initially, concerns surrounding vaccine efficacy, potential adverse effects, and the economic burden associated with large-scale vaccination campaigns led to hesitancy among poultry producers and industry stakeholders. Additionally, public health authorities grappled with challenges related to regulatory approval, vaccine strain selection, and the development of robust surveillance systems. Over time, advancements in vaccine technology and extensive research demonstrating the safety and effectiveness of HPAI vaccines have gradually shifted perceptions. Adopting innovative vaccination strategies, such as vector-based vaccines and recombinant technologies, has addressed previous limitations and bolstered confidence in immunization as a viable control measure. Moreover, collaborative efforts between international organizations, governments, and research institutions have played a pivotal role in establishing standardized vaccine development, distribution, and administration protocols. These endeavors have facilitated harmonizing global strategies and enhanced the preparedness and response mechanisms for potential HPAI outbreaks. Consumer attitudes have also evolved, driven by increased awareness of the public health implications of avian influenza and a growing demand for sustainable and ethically produced poultry products. This shift in consumer sentiment has incentivized industry stakeholders to embrace vaccination as a proactive measure to safeguard both avian welfare and human health. In conclusion, this abstract highlights the transformative journey of HPAI vaccination programs, underscoring the pivotal role of scientific innovation, collaborative partnerships, and evolving consumer perspectives in overcoming initial resistance. As the global community continues to confront emerging infectious diseases, the successful trajectory of HPAI vaccination provides valuable insights into the dynamic interplay between science, policy, and public perception in the face of evolving health challenges.

Rational approach to vaccination against highly pathogenic avian influenza in Nigeria: a scientific perspective and global best practice.

Since 2006, highly pathogenic avian influenza (HPAI) subtypes H5Nx have adversely affected poultry production in Nigeria. Successive waves of infections in the last two decades have raised concerns about the ability to contain infections by biosecurity alone, and evidence of recurrent outbreaks suggests a need for adoption of additional control measures such as vaccination. Although vaccination can be used to control virus spread and reduce the morbidity and mortality caused by HPAI, no country using vaccination alone as a control measure against HPAI has been able to eliminate or prevent re-infection. To inform policy in Nigeria, we examined the intricacies of HPAI vaccination, government regulations, and scientific data regarding what kind of vaccines can be used based on subtype, whether inactivated or live attenuated should be used, when to deliver vaccine either proactively or reactively, where to apply vaccination either in disease control zones, regionally, or nationally, and how to vaccinate the targeted poultry population for optimum success. A resurgence of HPAI outbreaks in Nigeria since 2018, after the country was declared free of the epidemic following the first outbreak in 2006, has led to enhanced intervention. Controlled vaccination entails monitoring the application of vaccines, the capacity to differentiate vaccinated from infected (DIVA) flocks, and assessing seroconversion or other immune correlates of protection. Concurrent surveillance for circulating avian influenza virus (AIV) and analyzing AIV isolates obtained via surveillance efforts for genetic and/or antigenic mismatch with vaccine strains are also important. Countries with high investment in commercial poultry farms like Nigeria may identify and zone territories where vaccines can be applied. This may include ring vaccination to control HPAI in areas or production systems at risk of infection. Before adoption of vaccination as an additional control measure on commercial poultry farms, two outcomes must be considered. First, vaccination is an admission of endemicity. Secondly, vaccinated flocks may no longer be made accessible to international poultry markets in accordance with WOAH trade regulations. Vaccination must therefore be approached with utmost caution and be guided by science-based evidence throughout the implementation strategy after thorough risk assessment. Influenza vaccine research, development, and controlled application in addition to biosecurity may be a precautionary measure in the evolving HPAI scenario in Nigeria.

Using surveillance data for early warning modelling of highly pathogenic avian influenza in Europe reveals a seasonal shift in transmission, 2016–2022

Avian influenza in wild birds and poultry flocks constitutes a problem for animal welfare, food security and public health. In recent years there have been increasing numbers of outbreaks in Europe, with many poultry flocks culled after being infected with highly pathogenic avian influenza (HPAI). Continuous monitoring is crucial to enable timely implementation of control to prevent HPAI spread from wild birds to poultry and between poultry flocks within a country. We here utilize readily available public surveillance data and time-series models to predict HPAI detections within European countries and show a seasonal shift that happened during 2021–2022. The output is models capable of monitoring the weekly risk of HPAI outbreaks, to support decision making.