Highly pathogenic H5N1 avian influenza was first confirmed on 10 January 2008 and to date 11 dead birds in the area have tested positive for the virus.
It is 30 days since collection of the last positive bird, but experts warn that infection may still be found both in this area or elsewhere in the country.
The UK is at a constant and low level of risk of the introduction of H5N1, with a slight increase in risk during winter and spring migration.
Deputy chief vet, Alick Simmons, said: “Our active surveillance and sampling in the area has provided evidence that the virus has been confined to mute swans and a single Canada goose, at a very low level.
There is no evidence of disease spreading to domestic birds nor any further cases in wild birds in the past 30 days.
“Given the constant disease risk, further cases of a highly pathogenic strain of avian flu are to be expected. Therefore, I would urge all bird keepers across the country to remain vigilant for signs of disease, and maintain good biosecurity practices.”