The first two cases of highly pathogenic avian influenza (bird flu) subtype H5N8 ever recorded in commercial poultry flocks in NI were “most likely” linked together by vehicle movements between the two sites, a DAERA investigation into the outbreak has concluded.
The first clinical signs of the disease were identified on 27 December 2020 in a commercial layer flock, consisting of two 16,000 deep litter bird houses, near Clough in Co Antrim.
DAERA was notified by a private poultry vet on 30 December that it was a suspect case of bird flu. The outbreak was confirmed the following week.
Family members also operated a nearby free-range egg layer flock with two houses of 16,000 birds each, and a rearing house with 16,000 three-week-old birds.
While no clinical signs were identified in these premises, they were classed as “dangerous contacts”, and birds at all three sites were culled on 7 January.
The DAERA investigation into the outbreak concluded that the sites were well managed, but given their proximity to recent cases of bird flu found in swans, “the evidence collected would suggest that indirect introduction from wild birds was the source of infection”.
The second outbreak was at a commercial egg layer site consisting of one house containing 31,000 birds kept in colony-enriched cages.
First signs of the disease were identified on 3 January. There was a rapid increase in mortality, with an estimated 50% of the birds dying by 7 January. All birds were culled the following day.
The DAERA investigation found that both the Clough and Lisburn farms were suppliers to the same egg packer, and utilised the same feed delivery lorry company.
A collection lorry visited both premises on the same egg collection round on 21 December 2020.
The report concludes that this lorry was the “most likely” source of infection for the Lisburn outbreak, although the authors also point out that indirect introduction from wild birds or from other movements onto the site cannot be ruled out.