February 3, 2015

expert reaction to case of H7 avian flu being confirmed in chickens at a farm in Hampshire

A chicken farm in Hampshire has had the presence of bird flu confirmed, though it is a “low severity” H7 strain which is less serious than the H5N8 strain which was found at a farm in Yorkshire in November 2014.

Prof. Mark Fielder, Professor of Medical Microbiology, Kingston University, said:

“The avian influenza virus that has been discovered on a farm in Hampshire is one of the H7 strains and of lower severity than the H5 strain found on a farm in Yorkshire late 2014. These strains are different and do not come from the same outbreak. This suspected H5N7 strain of avian influenza represents very little risk to the human population in terms of infection or contamination of the food chain. Currently rapid and robust action has the infection under control. What is needed now is ongoing vigilance to ensure that if further cases are identified prompt action can be taken to prevent further spread.”

Dr Nicola Lewis, Research Associate in the Department of Zoology, University of Cambridge, said:

“If the virus is confirmed as a low pathogenic – or low severity – H7N7 avian influenza virus then the investigating authorities will try to work out where it might have come from and how it might have infected the chickens on the farm. It is a different subtype and severity of influenza virus from the H5N8 case last November in Yorkshire so these two outbreaks are not directly linked.

“Low pathogenic avian flu viruses naturally infect wild birds. These wild birds get several influenza infections a year, often with different subtypes of influenza, and usually these wild birds don’t appear sick.

“These wild birds also migrate and can carry their influenza viruses among geographic regions.

“The investigating scientists will be able to compare the virus genetic material from this outbreak to influenza viruses in both wild and domestic birds, from both within and outside the UK to try to work out where it might have come from. In the meantime, the control measures taken on the farm by the UK authorities will ensure that the virus doesn’t mutate into something more severe and so safeguard human health.”

Dr Derek Gatherer, Lecturer in Bioinformatics, Lancaster University, said:

“H7N7 is a completely different sub-type of avian influenza A to H5N8.  H5N8 is relatively new, and is a hybrid (“re-assortant” is the technical term) between the old H5N1 highly pathogenic strain and an unknown other strain.  H7N7 on the other hand is much more familiar, and exists in two continental varieties – North American and Eurasian. I would guess that the Hampshire strain will turn out to be a Eurasian one. There have been occasional infections of humans with H7N7, most recently in Italy in late August 2013, and prior to that in the Netherlands in February 2003.  None of these cases were severe, and all patients fully recovered. The virus is only transmitted from birds to humans and not from person-to-person. There is no danger to the general public.”

https://www.gov.uk/government/news/low-severity-avian-flu-confirmed-in-hampshire

Declared interests

Dr Nicola Lewis is funded by a DTRA FRCWMD Broad Agency Announcement HDTRA1-09-14-FRCWMD GRANT11177182 and by the US National Institute of Allergy and Infectious Diseases Centers of Excellence for Influenza Research and Surveillance (CEIRS) Program to investigate avian influenza viruses in wild and domestic birds.