Urgent request on avian influenza

Abstract

Highly pathogenic avian influenza (HPAI) H5N8 is currently causing an epizootic in Europe, infecting many poultry holdings as well as captive and wild bird species in more than 10 countries. Given the clear clinical manifestation, passive surveillance is considered the most effective means of detecting infected wild and domestic birds. Testing samples from new species and non-previously reported areas is key to determine the geographic spread of HPAIV H5N8 2016 in wild birds. Testing limited numbers of dead wild birds in previously reported areas is useful when it is relevant to know whether the virus is still present in the area or not, e.g. before restrictive measures in poultry are to be lifted. To prevent introduction of HPAIV from wild birds into poultry, strict biosecurity implemented and maintained by the poultry farmers is the most important measure. Providing holding-specific biosecurity guidance is strongly recommended as it is expected to have a high impact on the achieved biosecurity level of the holding. This is preferably done during peace time to increase preparedness for future outbreaks. The location and size of control and in particular monitoring areas for poultry associated with positive wild bird findings are best based on knowledge of the wider habitat and flight distance of the affected wild bird species. It is recommended to increase awareness among poultry farmers in these established areas in order to enhance passive surveillance and to implement enhanced biosecurity measures including poultry confinement. There is no scientific evidence suggesting a different effectiveness of the protection measures on the introduction into poultry holdings and subsequent spread of HPAIV when applied to H5N8, H5N1 or other notifiable HPAI viruses.

Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4b in Germany in 2016/2017

“…Fortunately, the recent HPAIV H5N8 clade 2.3.4.4a and b had no zoonotic potential, but this is prone to change as new viruses within this clade (2.3.4.4c and d) that may lead to fatal infections in mammals have already evolved in Asia (8). Efficient measures to prevent the spread of notifiable AIV include prompt detection of infection, closing affected holdings already in the case of suspected infections, immediate depopulation and cleansing/disinfection, as well as a temporary ban on restocking (7). Moreover, potential contact to wild birds, mode and frequency of farm visits, biosecurity practices, and the density of poultry holdings in a specific region are relevant risk factors for the introduction and the spread of HPAIVs (16).…”

“…The generation of a potentially pandemic virus from this lineage that is able to spread within the human population is of worldwide concern and under careful observation. Genetic analysis and animal experiments showed that there was no indication of a zoonotic potential of the clade 2.3.4.4 H5N8a and b viruses (7) and no human infections with this virus have been reported so far. However, 2.3.4.4c H5N6 viruses, which have hitherto only been detected in South East Asia, bear a zoonotic potential (8).…”

Avian influenza

“…In the recent 2016/2017 epizootic, poultry outbreaks and positive wild bird submissions showed a strong spatial correlation (EFSA, ECDC, EURL, 2017); however, positive wild bird submissions were not always indicative of subsequent poultry incursions. Passive wild surveillance is less useful in epizootics not associated with high levels of wild bird mortality.…”

Host factors drive the within-host competition between highly and low pathogenic H5N8 avian influenza viruses

“…We used reverse-genetics to generate the wild-type H5N8HP from a HPAIV isolated during the 2016 H5N8 epizootics in France [13]. This virus belonged to clade 2.3.4.4 group B, which caused high levels of mortality in Galliformes and in wild and domestic Anseriformes during the 2016-2017 HPAIV outbreak in Europe [13][14][15][16]. Using site-directed mutagenesis and reverse-genetics, we mutated the H5N8HP HA polybasic cleavage site PLRELRRLR/G to a monobasic cleavage site PQRETR/G to obtain the H5N8LP virus with a typical LPAIV HA sequence (NCBI Genbank accession number: AB261853.1) [17].…”