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

Abstract

Avian influenza (AI) is an important disease that has significant implications for animal and human health. High pathogenicity AI (HPAI) has emerged in consecutive seasons within the UK to cause the largest outbreaks recorded. Statutory measures to control outbreaks of AI virus (AIV) at poultry farms involve disposal of all birds on infected premises. Understanding of the timing of incursions into the UK could facilitate decisions on improved responses. During the autumnal migration and wintering period (autumn 2019- spring 2020), three active sampling approaches were trialled for wild bird species considered likely to be involved in captive AI outbreaks with retrospective laboratory testing undertaken to define the presence of AIV.Faecal sampling of birds (n = 594) caught during routine and responsive mist net sampling failed to detect AIV. Cloacal sampling of hunter-harvested waterfowl (n = 146) detected seven positive samples from three species with the earliest detection on the 17 October 2020. Statutory sampling first detected AIV in wild and captive birds on 3 November 2020. We conclude that hunter sourced sampling of waterfowl presents an opportunity to detect AI within the UK in advance of outbreaks on poultry farms and allow for early intervention measures to protect the national poultry flock.

Keywords: Bird flu; disease surveillance; epidemiology; migration ecology; ornithology; zoonotic.

Fig. 1.

Locations of migratory bird sampling sites at Filey Brigg (a), Welwick saltmarsh (b) and on the Spurn peninsula (c) within the UK [23].

Fig. 2.

Faecal sampling locations in response to December 2019 LPAI H5N3 captive outbreak near Athelington, Mid-Suffolk. No sampling took place at the outbreak site due to 1 km exclusion zone.

Fig. 3.

Locations of ringing location of already ringed Eurasian Teal shot on the Humber Estuary during winter 2020/2021.

Fig. 4.

Relative abundance (% of complete ebird species presence checklists where present per week) of migratory dabbling ducks in the UK from the 1 August 2020 to 1 March 2021 constructed from Ebird abundance data [29]. First detection dates for both passive and active methods are shown and labelled in vertical yellow lines. Month lines signify the week that included the first day of the month.