High pathogenicity avian influenza: targeted active surveillance of wild birds to enable early detection of emerging disease threats

Spread of avian influenza among poultry specialists in England during winter 2022/23: National poultry housing order and environmental drivers

Purpose

To examine the impact of the national poultry housing order the UK government introduced on 7 November 2022 on the spreading of the avian influenza virus among poultry premises.

Methods

A longitudinal design with 15 weeks of infected poultry specialist incidence rates per 100 poultry specialists during the 2022/23 winter for 8 English regions. A multilevel regression model was used to analyse repeated measurements. Time was level-1 unit and regions level-2 unit resulting in 120 observations. Random intercept models included interactions between housing order and weekly infected wild birds, poultry density, or weekly average temperatures divided into terciles. In models where these variables were not included as an interaction term they were introduced as confounders.

Results

After the introduction of the housing order, it took 3 weeks for a considerable reduction in poultry specialist incidence rates. Reduction in incidence rates was strongest in regions with highest poultry density, from 1.27 (95%CI 0.99 to 1.56) to 0.30 (95%CI 0.09 to 0.52). Considerable reductions were also seen in regions with most detected infected wild birds.

Conclusion

The housing order was successful in reducing infected poultry specialist incidence rates three weeks after its introduction. Strongest impact in regions with highest poultry density.

A multi-species, multi-pathogen avian viral disease outbreak event: Investigating potential for virus transmission at the wild bird - poultry interface

AbstractA free-range organic broiler (Gallus gallus domesticus) premises in Staffordshire was infected by high pathogenicity avian influenza virus (HPAIV) H5N8 during the 2020-2021 epizootic in the United Kingdom (UK). Following initial confirmation of the infection in poultry, multiple wild bird species were seen scavenging on chicken carcasses. Detected dead wild birds were subsequently demonstrated to have been infected and succumbed to HPAIV H5N8. Initially, scavenging species, magpie (Pica pica) and raven (Corvus corax), were found dead on the premises but over the following days, buzzards (Buteo buteo) were also found dead within the local area with positive detection of HPAIV in submitted carcasses. The subacute nature of microscopic lesions within a buzzard was consistent with the timeframe of infection. Finally, a considerable number of free-living pheasants (Phasianus colchicus) were also found dead in the surrounding area, with carcasses having higher viral antigen loads compared to infected chickens. Limited virus dissemination was observed in the carcasses of the magpie, raven and buzzard. Further, an avirulent avian paramyxovirus type 1 (APMV-1) was detected within poultry samples as well as in the viscera of a magpie infected with HPAIV. Immunohistochemistry did not reveal colocalization of avian paramyxovirus antigens with lesions, supporting an avirulent APMV-1 infection. Overall, this case highlights scenarios in which bi-directional transmission of avian viral diseases between commercial and wild bird species may occur. It also underlines the importance of bio separation and reduced access when infection pressure from HPAIV is high.

Surveillance and Genetic Analysis of Low-Pathogenicity Avian Influenza Viruses Isolated from Feces of Wild Birds in Mongolia, 2021 to 2023

The introduction of novel highly pathogenic (HPAI) viruses into Korea has been attributed to recombination events occurring at breeding sites in the Northern Hemisphere. This has increased interest in monitoring and genetically analyzing avian influenza viruses (AIVs) in northern regions, such as Mongolia, which share migratory bird flyways with Korea. AIVs in Mongolia were monitored by analyzing 10,149 fecal samples freshly collected from wild birds from April to October in 2021 to 2023. The prevalence of AIVs in wild birds was 1.01%, with a total of 77 AIVs isolated during these 3 years. These 77 AIVs included hemagglutinin (HA) subtypes H1, H2, H3, H4, H6, H10 and H13 and neuraminidase (NA) subtypes N1, N2, N3, N6, N7 and N8. The most frequently detected subtype combinations were H3N8 (39.0%) and H4N6 (19.5%), although HPAI viruses were not detected. Genetic analysis indicated that theses AIVs isolated from Mongolian samples were closely related to AIVs in wild birds in Korea, including those of Eurasian lineage. These findings indicate the necessity of continuous AIV surveillance and monitoring, as HPAI viruses introduced into Korea may derive from strains in Mongolia.

Biosecurity implementation on large-scale poultry farms in Europe: A qualitative interview study with farmers

Biosecurity is an essential tool for rearing healthy animals. Biosecurity measures (BMs) are well known in poultry production, but it is difficult to assess actual implementation on farms. The aims of this qualitative study were (1) to provide an overview of biosecurity implementation according to poultry farmers in Europe; and (2) to better understand the reported reasons and potential obstacles for not implementing the measures. In seven European Union Member States, 192 farmers (118 under contract with a company and 68 independents) working in seven different categories of poultry production were interviewed on 62 BMs to determine the frequency of implementation and the reasons for non-implementation. Most of the replies (n = 7791) concerning BM implementation were reported by the farmers as "always" implemented (81%), statistically higher for breeders (87%) and layers (82%) and lower for independent farms versus farms under contract with a company (79.5% and 82.5%, respectively). Regardless the poultry production category, the most frequently implemented BMs declared by the farmers were daily surveillance of birds, rodent control and feed storage protection. Standard hygiene practices were also mentioned as high-implementation measures for most production categories, with some deficiencies, such as rendering tank disinfection after each collection and, for meat poultry, disinfection of the feed silo and bacterial control of house cleaning and disinfection between each cycle. The entry of vehicles and individuals onto poultry farms, especially during critical points of eggs collection for breeders and layers, as well as the presence of other animals, such as the "all in/all out" practice, particularly in layers and ducks, were also reported as the least commonly practiced measures. The main reasons for not implementing the measures (n = 1683 replies) were low awareness and poor knowledge of the expected benefits of biosecurity ("no known advantages" 14%, and "not useful" 12%), the lack of training ("not enough training" 5% and "advice" 7%), lack of time (19%), and financial aspects (17%). Despite the good overall biosecurity mentioned by the farmers, these findings highlight certain deficiencies, suggesting room for improvement and the need for targeted and tailored support of poultry farmers in Europe.

New Patterns for Highly Pathogenic Avian Influenza and Adjustment of Prevention, Control and Surveillance Strategies: The Example of France

From 2020 up to summer 2023, there was a substantial change in the situation concerning the high pathogenic avian influenza (HPAI) virus in Europe. This change concerned mainly virus circulation within wildlife, both in wild birds and wild mammals. It involved the seasonality of HPAI detections, the species affected, excess mortality events, and the apparent increased level of contamination in wild birds. The knock-on effect concerned new impacts and challenges for the poultry sector, which is affected by repeated annual waves of HPAI arriving with wild migratory birds and by risks due to viral circulation within resident wild birds across the year. Indeed, exceeding expectations, new poultry sectors and production areas have been affected during the recent HPAI seasons in France. The HPAI virus strains involved also generate considerable concern about human health because of enhanced risks of species barrier crossing. In this article, we present these changes in detail, along with the required adjustment of prevention, control, and surveillance strategies, focusing specifically on the situation in France.

Stakeholders' Perceptions of Biosecurity Implementation in Italian Poultry Farms

The level of implementation of biosecurity measures (BMs), the reasons for not implementing BMs and the effectiveness of BMs were assessed according to the perceptions of stakeholders (i.e., farmers and advisors) in Italian poultry farms. For this purpose, data were collected using a questionnaire administered to advisors (n = 37) and farmers (n = 30) of conventional broiler (n = 13) and layer (n = 13), free-range broiler (n = 8) and layer (n = 10), turkey (n = 13), duck (n = 3) and breeder (n = 7) farms between April and September 2021. The frequency of the implementation of BMs was 66.97% and 81.14% according to the answers provided by the advisors and farmers, respectively, with the breeder sector showing the highest level of implementation (85.71%). "Not knowing advantages" (21.49% for advisors) and "other/specific reasons" (21.49% for advisors and 38.32% for farmers) were the most common answers regarding the lack of implementation of BMs for all poultry sectors. Only 31.09% of farmers acknowledged the effectiveness of not-implemented BMs in contrast to 61.02% of advisors, with the layers' stakeholders being the most aware. The findings of this study may be useful for identifying failures in biosecurity and failures to develop intervention strategies to fulfil the biosecurity gaps still present in Italian poultry farms.