Global Migratory Bird Flyways
#15,547
Clade 2.3.4.4 H5 avian influenza viruses - which have recently returned to Northern Europe and Asia after a 3 year absence (see More Avian Flu Reports from Japan, Germany, France & The Netherlands) - are known for their ability to successfully reassort with other (mostly LPAI) viruses they encounters in their travels, spinning off new genotypes, and occasionally, new subtypes as well.
Although a deep concern to the poultry industry, and a threat to wild birds - unlike HPAI H5N1 and the (Asian) HPAI H5N6 subtypes - these European HPAI H5 viruses have never been known to infect humans.
While past performance is no guarantee of future results, and reasonable personal precautions are warranted for those in contact with sick birds, the public health risk from these viruses is currently considered low.
Last week, however, a pre-print article (see Pre-Print: Novel Incursion of a HPAI H5N8 Virus in the Netherlands, October 2020), described this latest incursion by HPAI H5 into Europe as genetically distinct from recently circulating strains.
Today Germany's Friedrich-Loeffler-Institut (FLI) has published a reassuring risk assessment, which reiterates the lack of known zoonotic threat by these subtypes.
(translated)
Current avian influenza / bird flu cases in Germany: No indication of the risk of infection for humans
11/9/2020
Since the end of October the National Reference Laboratory for Avian Influenza / Avian Influenza of the Friedrich-Loeffler-Institut (FLI) has confirmed cases of avian influenza in a number of wild birds in northern Germany and in two farms in Schleswig-Holstein. The infections were caused by various avian influenza viruses (highly pathogenic avian influenza viruses, HPAIV).
Genetic analyzes of the complete virus genome assign the currently occurring viruses to the subtype H5. A number of virus variants (H5N8, H5N5, H5N1) that are genetically related to the H5N8 viruses that appeared in Europe in 2016/2017 were detected.
As with the H5 viruses from 2016/2017, there is currently no evidence that the current H5 viruses can infect humans. So they are not zoonotic viruses. The current H5 viruses are only largely related to the H5N1 viruses, which are dangerous for humans and which also appeared in Europe in 2006/2007. The current risk assessment of the FLI provides more information on the origin of the current viruses of the subtype.
Phylogenetic studies of the HPAI H5 viruses, which were obtained, for example, from dead mute swans in the Netherlands near Utrecht and from a buzzard in Germany, suggest a new entry. The viruses analyzed so far belong to clade 2.3.4.4b, like the HPAIV H5N8 introduced since 2016, but are not directly phylogenetically related to the H5N8 viruses that caused the outbreaks in Europe in the first half of 2020.Instead, the viruses analyzed have a new genetic signature that shows similarities to various viruses from Eurasia in recent years. Similarities are particularly evident in the HA gene for viruses from 2016/2017. Sequence comparisons with the viruses from the Netherlands show both similar and different segments.This suggests, that the current virus strain, similar to 2016/17, allows an increased genetic reassortment (e.g. H5N5, H5N1). Based on the previous information on dead finds and the species distribution, a comparable virulence of the new reassortants to that of the HPAIV H5Nx from 2016 to 2019 can be assumed. The same applies to the zoonotic risk. So far there is no evidence that the new reassortants have a zoonotic potential.
link
Risk assessment for the occurrence of HPAIV H5 in Germany, as of November 5th, 2020 (PDF, not accessible)
