Avian influenza overview November 2018 – February 2019

Abstract

No human infections due to highly pathogenic avian influenza (HPAI) A(H5N8) or A(H5N6) viruses ‐ detected in wild birds and poultry outbreaks in Europe ‐ have been reported so far and the risk of zoonotic transmission to the general public in Europe is considered very low. Between 16 November 2018 and 15 February 2019, two HPAI A(H5N8) outbreaks in poultry establishments in Bulgaria, two HPAI A(H5N6) outbreaks in wild birds in Denmark and one low pathogenic avian influenza (LPAI) A(H5N3) in captive birds in the Netherlands were reported in the European Union (EU). Genetic characterisation of the HPAI A(H5N6) viruses reveals that they cluster with the A(H5N6) viruses that have been circulating in Europe since December 2017. The wild bird species involved were birds of prey and were likely infected due to hunting or scavenging infected wild waterfowl. However, HPAI virus was not detected in other wild birds during this period. Outside the EU, two HPAI outbreaks were reported in poultry during the reporting period from western Russia. Sequence information on an HPAI A(H5N6) virus found in a common gull in western Russia in October 2018 suggests that the virus clusters within clade 2.3.4.4c and is closely related to viruses that transmitted zoonotically in China. An increasing number of outbreaks in poultry and wild birds in Asia, Africa and the Middle East was observed during the time period for this report. Currently there is no evidence of a new HPAI virus incursion from Asia into Europe. However, passive surveillance systems may not be sensitive enough if the prevalence or case fatality in wild birds is very low. Nevertheless, it is important to encourage and maintain a certain level of passive surveillance in Europe testing single sick or dead wild birds and birds of prey as they may be sensitive sentinel species for the presence of HPAI virus in the environment. A well‐targeted active surveillance might complement passive surveillance to collect information on HPAI infectious status of apparently healthy wild bird populations.

First detection of highly pathogenic H5N6 avian influenza virus on the African continent

“…Here, the first H5N6 clade 2.3.4.4.b introduction into Africa from Europe, most likely via wild birds is reported. HPAI H5N6 bearing the same gene constellation of the Nigerian strain, had already caused a total of 98 outbreaks in Europe between late-2017 and early 2019, of which 92% had occurred in wild birds [12]. This finding confirms our previous study, which recognized West Africa, and in particular Nigeria, as one of the most important hotspot for Gs/GD/96 HPAI H5Nx introduction into Africa [5].…”

Pathology of naturally acquired high pathogenicity avian influenza virus H5N1 infection in seabirds

“…During the 2020-2021 and 2021-2022 outbreaks of high pathogenicity avian influenza in the UK, there has been an increased detection of HPAIV H5N1 in seabirds of the Orders Suliformes and Laridae. 3,6,16,34 This investigation of naturally acquired infection revealed that gross pathology was limited to pancreatic necrosis in the herring gull and proventricular ulceration in the great skua. The pancreatic changes were less characteristic compared to that in Galliformes and Anseriformes and required immunohistochemical confirmation.…”

Avian influenza overview August – December 2020

“…In contrast to the last report, no case of HPAI A(H5N2) was reported to the OIE between 16 August and 25 November. The Taiwanese lineages of HPAI A(H5N2) (clade 2.3.4.4) differ from the Eurasian HPAI A(H5N2) lineage (Li et al, 2020); the latter belonging to clade 2.3.4.4b, which has been detected, with different genotypes, in Egypt and Russia as well as in Asian countries between 2016 and 2019 (EFSA et al, 2019a) and in Bulgaria in 2020.…”