Monday, May 31, 2021

Netherlands: Two Foxes Test Positive For (non-Zoonotic) Avian H5N1


We've a bit of an unusual report from Wageningen Bioveterinary Research (WBVR) in the Netherlands where they report finding two foxes in the province of Groningen that have been infected with avian H5N1.

While we have seen many instances of dogs, cats, and other peridomestic mammals infected with the infamously  zoonotic `Asian' H5N1 virus, it is more unusual to see symptomatic infection with the European avian H5Nx virus in mammals (a notable exception being seals).  

That is . . until recently.  In March of this year the UK's DEFRA announced:

Other events in England

H5N8 influenza of avian origin was detected as part of routine wildlife surveillance in 3 seals and a fox that died at a wildlife rehabilitation centre in England. Wild birds undergoing rehabilitation in the centre are believed to have been the source of the infection. There was no evidence of spread from the premises.

This report raised some eyebrows as it came on the heels of the first confirmed zoonotic jump of avian H5N1 to humans (see Science: Emerging H5N8 Avian Influenza Viruses), reported by Russia earlier this year. 

The H5N1 virus referenced in today's announcement is a reassortment of the European H5N8 virus - likely with a local LPAI HxN1 virus - and undoubtedly shares much in common with its parental H5N8. 

While not as concerning as a zoonotic jump, anytime we see an avian influenza virus turn up in a mammalian host, it raises concerns.  The announcement, published over the weekend, from the Wageningen University & Research website follows:.

Published on May 28, 2021

Wageningen Bioveterinary Research (WBVR) has diagnosed bird flu in two foxes from the province of Groningen in the Netherland and characterized the viruses as H5N1. The sequences of the avian flu viruses in the foxes are similar to those identified in infected wild birds from the same region. It is therefore likely that the foxes became infected from eating a bird infected with bird flu. The virus found in foxes is not related to the zoonotic HPAI H5N1 strains that have also infected humans in Asia.

H5N1 infections in foxes have been previously observed in other parts of the world and recently in England. Extensive spread of the virus among foxes is unlikely as foxes generally live in families and not in large groups. In addition, an infected fox develops serious symptoms within a few days, which avoids moving for far distances. Therefore, the risk of extensive spread within the foxes is rated as low. The foxes are thought to be unlikely to transmit the virus to other wild animals. However, other wild animals such as seals, dogs and cats are known to be susceptible to bird flu. Recently, HPAI H5N8 virus, to which the HPAI H5N1 virus is genetically related, has been detected in seals in England and Sweden.

Advice to leash dogs in parts of Friesland and Groningen
Avian influenza has recently only been diagnosed in dead wild birds in wetlands in the Dutch provinces Friesland and Groningen. Therefore, the advice from the Dutch Ministry of Agriculture, Nature and Food Quality is to keep dogs on a leash in these provinces to prevent dogs from coming into contact with infected dead birds. It remains important not to touch or move dead and sick birds yourself. If you find dead birds, you can report this via the site of the Dutch Wildlife Health Center or the National Animal Diseases Reporting Center. More information can be found on the NVWA website.

Importance of monitoring
Dead Barnacle Geese and birds of prey that are infected with HPAI H5N1 viruses are still found in the provinces of Friesland and Groningen. Most migratory birds have now left the Netherlands, but Barnacle Geese - the species in which the bird flu virus mainly circulates during the recent outbreak - is currently gathering in the north of the Netherlands before continuing to their breeding grounds in Siberia. On the other hand, there will be an increase in young birds in the near future. These young birds have never come into contact with avian influenza viruses before and are therefore susceptible to infections. It is unclear what influence this will have on the extent to which the virus continues to circulate within wild birds populations. Bird flu monitoring is important to determine whether the virus is still present in wild birds in the Netherlands. In addition, it is useful to monitor other sensitive animal species.

Extension of the confinement obligation
The Dutch expert group on animal diseases carried out a risk assessment of the risk of contamination of Dutch poultry farms with bird flu on 21 May 2021. The recent contamination on the turkey farm in Weert, the Netherlands, was not yet known at that time. The experts estimated the risk of a Dutch poultry farm becoming infected with HPAI at that time as moderate to high. They estimated the risk in the Northern Netherlands to be higher (high) than in the rest of the Netherlands (moderate to high). After the recent contamination in Weert, the Dutch Ministry of Agriculture, Nature and Food Quality has decided that the risk that a Dutch poultry farm will become infected with HPAI virus has not yet decreased sufficiently to withdraw the confinement and protection obligation. The Dutch expert group on animal diseases will continue to evaluate the risk on a weekly basis in the coming period.