A poultry worker is suffering from conjunctivitis after contracting the H7 strain of bird flu, the Health Protection Agency has confirmed.
Culled chickens have been removed from Witford Lodge Farm
The person was infected through close contact with birds at the Witford Lodge Farm in North Tuddenham, Norfolk, which had the disease.
H7 has no relationship to the deadly H5N1 strain which has killed over 100 people, mainly in South Asia.
The Health Protection Agency said the worker has no other symptoms.
It added that the worker, who does not want to be named, has the H7N3 strain of bird flu which is not highly infectious and last seen in the UK in 1979.
The worker 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 infection to date, the virus has only caused a mild disease," it said in a statement.
"Therefore, the risk to the general public in this outbreak is extremely limited."
Conjunctivitis causes red, sore, itchy eyes and the worker has no respiratory symptoms.
To date, most human cases of H7 avian influenza have presented with conjunctivitis only.
An unconfirmed number of other workers are already taking the same drug to prevent the illness.
They are also being offered the seasonal flu jab to prevent the H7 virus from mixing with any human flu viruses that may be circulating.
Nose and throat swabs and blood tests are also being taken from the other workers, and their health is being closely monitored.
Close contacts of the infected worker are also being given advice and preventative medication as appropriate.
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.
"Almost all human H7 infections documented so far have been associated with close contact with dead or dying poultry.
"The threat to human health posed by H7 avian influenza viruses remains very low despite the recent developments in Norfolk."
Alan Hay, director of the Medical Research Council's World Influenza Centre, said: "These sporadic human infections do happen in the case of H7 when people are in very close contacts with birds.
"You have to keep this in context, people in close contact have to take sensible precautions such as wearing eye masks and gloves but this is not an infection that other people should be concerned about catching."
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".