The deadly H5N1 strain of bird flu has been found in another dead swan in Dorset in the UK.
This is the fifth swan to test positive for the H5N1 virus at Abbotsbury Swannery - four birds tested positive for the virus during routine surveillance.
While all the workers at the swannery have been given Tamiflu tablets as a precaution, the Department for the Environment, Food and Rural Affairs (Defra) says there is currently no evidence to suggest widespread disease in the wild bird population.
A 3km control zone and a 10km monitoring area have been established around the swannery to try to curb the spread of the virus and officials have warned bird keepers to be vigilant.
Officials say there is a "constant low-level risk" of avian influenza being introduced into the UK but the outbreak poses little risk to humans.
Farmers and bird keepers have been ordered to isolate flocks from wild birds near the swannery and so far no disease has been found in domestic birds.
While there are no plans to cull wild flocks another 800 swans will be tested.
The latest outbreak comes less than a month after restrictions on poultry movement were lifted in Norfolk and Suffolk which were imposed following an outbreak of bird flu on a free-range turkey farm in November.
Experts believe wild birds are the culprits but say it is unusual that the outbreak has occurred outside a migration period; they speculate it may have been brought to the region some time ago but only recently infected the birds.
The swannery, which was established by Benedictine monks in the 11th century, is near Chesil beach and is a tourist attraction.
It claims to be the only managed colony of mute swans in the world.
The deadly H5N1 avian virus continues to cause concern around the world with experts fearing the virus will ultimately mutate into a form easily passed from human to human.
This scenario has the potential for a pandemic which could kill millions.
To date the virus has killed 216 people out of 349 infected in 12 countries in Asia and Africa; it has also been responsible for the death and culling of millions of birds.