Yorkshire bird flu outbreak ‘very low risk to humans’ says Defra

Government officials and scientists investigating an outbreak of avian influenza in East Yorkshire have played down the risk to human health.

Defra confirmed on Sunday (16 November) that the strain found on the Yorkshire duck farm was the H5 high pathogenic variety, but insisted that this came with a “very low risk to human health and no risk to the food chain”.

The message has been supported by both Public Health England and the Food Standards Agency.

And while it will take some time to establish the “N type” of the virus, Defra has already ruled out the H5N1 strain, which is known to be infectious to humans.

British Poultry Council chief executive Andrew Large said avian influenza was a disease of birds and the risk to the general public was “negligible”.

See also: Bird flu confirmed on Yorkshire duck farm

“Consumers should continue to support British poultrymeat, assured that there is no risk in eating cooked poultry,” he said.

Dr Colin Butter, head of avian viral immunology and the Pirbright Institute agreed that, while it may be possible that this strain could infect people as the result of direct contact with infected birds, “this is likely to be a rare event and there is no suggestion that the virus could transfer from person to person”.  

Prof Andrew Easton, professor of virology, University of Warwick, added that the greater risk was to the poultry industry and recommended that infected birds be killed as quickly as possible to stop spread to other flocks.

“Aquatic birds, such as ducks, can harbour over 100 different types of influenza,” he said. “In these birds the viruses do not usually cause disease, but when certain types spread to domestic poultry, such as chickens, serious disease can be seen.”

Prof Wendy Barclay, chair in influenza virology, Imperial College London, agreed that the H5 and H7 sub-types were particularly feared because they can carry unusual sequence motifs that make them highly pathogenic in the birds, killing almost every infected bird in a matter of days.

“However, it is important to realise that not all H5 viruses have this motif, so we need to wait for detailed sequence information to be released before we know if the virus in Yorkshire is of this type.

“Only a small subset of avian influenza viruses infect humans, and these viruses can be of low or high pathogenicity in the birds.

“Even low pathogenicity bird viruses can cause severe disease in humans, like the H7N9 recently identified in China. In previous outbreaks of H5 viruses in the UK, no humans have been infected. Without undergoing further mutations these infections do not pass from person to person.”