Highly pathogenic avian influenza H5N8 in Poland in 2019–2020

Abstract

IntroductionRepeated incursions of highly pathogenic avian influenza virus (HPAIV) H5 subtype of Gs/GD lineage pose a serious threat to poultry worldwide. We provide a detailed analysis of the spatio-temporal spread and genetic characteristics of HPAIV Gs/GD H5N8 from the 2019/20 epidemic in Poland.Material and methodsSamples from poultry and free-living birds were tested by real-time RT-PCR. Whole genome sequences from 24 (out of 35) outbreaks were generated and genetic relatedness was established. The clinical status of birds and possible pathways of spread were analysed based on the information provided by veterinary inspections combined with the results of phylogenetic studies.ResultsBetween 31 December 2019 and 31 March 2020, 35 outbreaks in commercial and backyard poultry holdings and 1 case in a wild bird were confirmed in nine provinces of Poland. Most of the outbreaks were detected in meat turkeys and ducks. All characterised viruses were closely related and belonged to a previously unrecognised genotype of HPAIV H5N8 clade 2.3.4.4b. Wild birds and human activity were identified as the major modes of HPAIV spread.ConclusionThe unprecedentedly late introduction of the HPAI virus urges for re-evaluation of current risk assessments. Continuous vigilance, strengthening biosecurity and intensifying surveillance in wild birds are needed to better manage the risk of HPAI occurrence in the future.

Multiple Introductions of Reassorted Highly Pathogenic Avian Influenza H5Nx Viruses Clade 2.3.4.4b Causing Outbreaks in Wild Birds and Poultry in The Netherlands, 2020-2021

“…Then in late 2019 until June 2020, HPAI H5N8 clade 2.3.4.4b viruses caused outbreaks in Central and Eastern European countries. These viruses were generated by reassortment between HPAI H5N8 from sub-Saharan Africa and LPAI viruses from Eurasia ( 12 , 13 ). In October 2020, a novel H5N8 clade 2.3.4.4b virus was first detected in the Netherlands in wild mute swans ( 14 ), and subsequently spread all over Europe, causing massive outbreaks in wild birds and poultry ( 15 – 20 ).…”

Novel Clade 2.3.4.4b Highly Pathogenic Avian Influenza A H5N8 and H5N5 Viruses in Denmark, 2020

“…Starting in late 2019 and lasting until June 2020, novel HPAI clade 2.3.4.4b H5N8 viruses caused outbreaks in Central and Eastern European countries. These viruses were generated by reassortment between H5N8 from sub-Saharan Africa and LPAI viruses from Eurasia [ 5 , 6 ]. Since October 2020, clade 2.3.4.4b HPAI H5 viruses have been detected again in both wild birds and poultry in Europe, initially in The Netherlands, Germany, and Denmark, then shortly after in many other European countries [ 7 , 8 ].…”

Avian influenza overview December 2020 – February 2021

“…Information extracted from the scientific literature Smietanka et al (2020) described the clinical signs of natural HPAI H5N8 virus infection, clade 2.3.4.4b, in Poland in 2019-2020 in various poultry species. In turkeys, sudden and high mortality was observed, and clinical signs included depression, reduction in vocalisation, decreased feed and water intake and nervous signs such as tremors, incoordination, paralysis of the wings and fast alternate movements of the legs.…”