Avian influenza cases in Northern Ireland last winter all linked, new report finds

Several cases of avian influenza (AI) in commercial poultry flocks in Northern Ireland were all linked, a new report from DAERA has concluded. The sites with outbreaks were all managed by the same family.
The cases were the first ever incursions of highly pathogenic avian influenza in the province, and led to a cull of 80,000 birds.
Two outbreaks of HPAI H5N8 were confirmed in commercial poultry flocks in Northern Ireland during December 2020 and January 2021. The first was near Ballymena, and a later outbreak was near Lisburn, both in County Antrim.
The Ballymena site was a commercial layer rearing unit which reported neurological signs and increased mortality in one of two houses. The report states this site had contact with premises (a commercial layer site and another commercial layer rearing site) nearby that were managed by members of the same family.
Serological evidence of H5N8 infection was found on the second rearing site but H5N8 virus was only detected in one house of the infected premises. 
Extensive epidemiological investigations were carried out on all three sites and it was concluded that the most likely source of infection was indirect introduction from wild birds, the report states. Clinical signs were first detected on the second infected premises on 3 January 2021 in a single house commercial egg layer site where there was a dramatic increase in bird mortality. 
The epidemiological investigation concluded that vehicle movements from the index case was the most likely source of infection for this outbreak.
During November and December 2020, eight cases of HPAI H5N8 were discovered in swans at various locations around the Lough Neagh/Lough Beg/River Bann basin. Analysis showed these cases were closely related to other HPAI H5N8 viruses found in England, the Netherlands, Belgium and France in late 2020.