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Nearly three days after the initial announcement, we have confirmation that the avian flu outbreak in the Northwest of England is H7N7, although the official statement is long on reassurance and short on specifics.
While the pathogenicity of the virus isn’t addressed in the press release, the addendum Avian influenza declaration 13 July 2015 (PDF, 1.07MB, 14 pages) confirms this to be a `highly pathogenic’ strain.
There are two broad categories of avian influenza; LPAI (Low Pathogenic Avian Influenza) and HPAI (Highly Pathogenic Avian Influenza).
- LPAI viruses are quite common in wild birds, cause little illness, and only rarely death. They are not considered to be a serious health to public health. The concern is (particularly with H5 & H7 strains) that LPAI viruses (particularly in crowded poultry operations) have the potential to mutate into HPAI strains.
- HPAI viruses are more dangerous, can produce high morbidity and mortality in wild birds and poultry, and can sometimes infect humans with serious result. The type of bird flu scientists have been watching closely for the past decade has been HPAI H5N1 (and to a lesser extent HPAI H7s & H9s).
Before the middle of the last decade, there was no uniform requirement to report or track LPAI infections. That changed in 2006 when the OIE made reporting of LPAI H5 & H7 viruses mandatory. First the Defra report, then I’ll return with a bit more on the H7N7 virus.
Avian flu confirmed in Lancashire
From: Department for Environment, Food & Rural Affairs
First published: 10 July 2015
Last updated: 13 July 2015 , see all updates
Part of: Animal and plant health
A case of H7N7 avian flu has now been confirmed in Lancashire.
A case of H7N7 avian flu has now been confirmed in Lancashire.
A temporary control zone imposed on Friday at the affected farm has now been replaced by a 10 kilometre surveillance zone and an inner 3 kilometre protection zone. Restrictions remain in place and the humane culling of all birds at the farm is continuing.
Public Health England has confirmed that the risk to public health from this strain is very low. The Food Standards Agency has said there is no food safety risk for consumers.
The restrictions mean that all poultry farms within the 10 kilometre control zone around the infected premises are not allowed to move poultry, captive birds or other mammals except under licence.
Chief Veterinary Officer, Nigel Gibbens said:
Final tests results have confirmed a case of avian flu at a farm in Lancashire. Restrictions put in place last week will continue and the humane culling of all birds at the site is progressing. These actions are part of our tried and tested approach to dealing with previous outbreaks.
Public Health England has confirmed that the risk to public health from this strain is very low. The Food Standards Agency has said there is no food safety risk for consumers.
Bird keepers should remain alert for any signs of disease, report suspect disease to their nearest APHA office immediately and ensure they are maintaining good biosecurity on their premises.
We have a strong track record of controlling and eliminating previous outbreaks of avian flu in the UK. The outbreaks in Yorkshire last year and Hampshire in February were both successfully contained, allowing restrictions to be lifted at the earliest opportunity.
An investigation into this case is ongoing.
LPAI H7N7 was last reported in the UK last February in the South of England (see Defra: Avian H7 Virus Found In Hampshire Poultry).
Prior to the emergence of China’s H7N9 virus in the spring of 2013, H7 avian viruses had only a limited track record of causing human infection and (mostly mild) illness, and were viewed as posing a lesser threat HPAI H5.
- In 2003 a large outbreak of H7N7 (89 confirmed, 1 fatality) in the Netherlands – with nearly all reported cases having very mild (often just conjunctivitis) symptoms.
- The Fraser Valley H7N3 outbreak of 2004 resulted in at least two human infections, as reported in this EID Journal report: Human Illness from Avian Influenza H7N3, British Columbia.
- In 2006 1 person in the UK was confirmed to have contracted H7N3, and the following year, 4 people tested positive for H7N2 – both following local outbreaks in poultry.
- 3 mild cases in Italy in 2013 (see ECDC Update & Assessment: Human Infection By Avian H7N7 In Italy).
Except for China’s unusual H7N9 virus, most H7 avian viruses are considered only a serious threat to the poultry industry.
That said, H7 flu strains - like all influenza viruses – evolve over time.
Which means that though it may be mild or relatively benign in humans today, it may not always remain so. And so outbreaks of avian flu (LPAI & HPAI) are taken seriously, and dealt with quickly.
