Although the summer months are generally a slow season for HPAI avian flu - at least in the more temperate regions of the globe - it isn't terribly unusual to see reports of `mild', LPAI viruses any time of the year.
In early May, in DVFA orders 20,000 Ducks Culled Due To LPAI H5, we looked at a report out of Denmark of an outbreak in ducks near Holstebro, which was discovered due to routine surveillance.LPAI (low path avian influenza) viruses are often carried by wild birds and can occasionally find their way into poultry flocks. They (generally) pose little direct threat to poultry or humans.
But LPAI H5 and H7 viruses are a concern because they have a habit of mutating into far more dangerous HPAI (high path) viruses when they are allowed to spread unchecked in poultry (see chart below).
While most of our focus has been on abrupt reassortment events, over the past few years we've seen an increasing number of these spontaneous H5 and H7 LPAI-to-HPAI mutations.
- In Europe (see here, here, and here)
- Two years ago in the H7N8 outbreaks in Indiana (see Genome Announcements: LPAI-to-HPAI Mutation Cited in January's H7N8 Outbreak)
- And last year with H7N9 in Tennessee (see EID Journal: Mammalian Pathogenesis & Transmission of Avian H7N9 Viruses - Tennessee 2017).
Although spontaneous mutation from LPAI-to-HPAI doesn't happen all that often, the risk is considered great enough that all LPAI H5 and H7 outbreaks must be reported to the OIE, and immediate steps must be taken to contain and eradicate the virus.Which brings us to another report from Denmark's DVFA (The Danish Veterinary and Food Administration) ordering the depopulation of about 3,500 ducks in Vordingbord after routine surveillance detected LPAI H5.
Bird flu - current situation
On 26 June, low pathogenic avian influenza has been found in a gray duck seal in Vordingborg Municipality
Outbreaks of low pathogenic avian influenza in gråandebesætning
A gråandebesætning near Faksinge in Vordingborg was June 26 found infected with low pathogenic avian influenza H5. The samples were taken during the control of avian influenza in poultry farms and have been examined at the National Veterinary Institute. The crew of about 3,500 ducks will be culled to prevent the virus from developing into a more serious influenza (highly pathogenic avian influenza).
Food Administration has set up a 1km restricted zone around the infected herd. Within the restricted zone are special rules for particular the movement and transport of poultry.
Where is the restricted zone?
See map of the restricted zone here