What is thought to be the world's first case of bovine spongiform encephalopathy (BSE) in an animal born in 2002 has been discovered in what scientists are calling "a cluster" of infected young cows in Wales.
The discovery of the three cases on a farm in Dyfed, Wales, has caused anxiety in the farming community in Britain where farmers believed they had beaten the disease.
Scientists are examining the possibility that the animals were infected by the same route, namely infected feed imported from abroad.
Investigations carried out in Wales are being monitored by the Department of Agriculture and Food in Dublin which last month reported the discovery of BSE in a cow born in 2001.
The cows which were found with the disease were aged 36 months to 43 months. The first case was identified more than two months ago and the two others were confirmed at the end of last week.
A Department for Environment, Food and Rural Affairs spokesman would not confirm reports that it was the first time three cases born after 1996 had been linked to one farm and that the three-year-old cow was the first BSE case born as late as 2002 in Europe. There were 309 cases of BSE reported last year in Britain compared with more than 36,000 in 1992.
The BSE case reported last month in Ireland in a cow born in 2001 was the 12th case of BSE to be diagnosed in animals born after 1997: four in 1998-born animals; seven in 1999-born animals; and one in a 2001-born animal.
Investigations into the source of the disease in two animals on one Munster farm found that the animals may have been exposed to infection through environmental contamination with carcass parts associated with the operation of a contiguous illegal knackery.