Bird flu

It is important to remember that H7 avian flu remains largely a disease of birds, say Dr Jonathan Van Tam, HPA.

The workers has not required hospital treatment. He or she was given the antiviral drug Tamiflu as a precautionary measure on Thursday as soon as the HPA was told about the outbreak. The strain is not easily passed from poultry to people, or from person to person, the HPA said.

"In almost all cases of human H7 infecton to date, the virus has only caused a mild disease," it said in a statemant.

"Therefore, the risk to the general public in this outbreak is extremely limited."

Dr Jonathan Van Tam, a flu expert at the HPA, said: "It is important to remember that H7 avian flu remains largely a disease of birds.

"The virus does not transmit easily to humans, as evidenced by the small number of confirmed infections worldwide to date.

The Department for the Environment, Food and Rural Affairs confirmed that the 34,000 birds on the infected farm will still be slaughtered, and a 1km exclusion zone will remain in place.

The World Health Organization says not all H5 or H7 strains are severe, but their ability to mutate means their presence is "always a cause for concern".

What is the H7 strain?

H7 versions of bird flu are highly infections to chickens, but are less threatening to humans than the H5N1 strain. The strain found in dead chickens on Witford Lodge Farm at Hockering, Norfolk was H7N3.

By: Rozsnyai Gábor