Cattle imported to Scotland from Roscommon last year have been found responsible for bringing brucellosis into Scotland, which had been free of the disease since 1973.
Details of the case emerged last week when two of the imported animals aborted due to the infection on a farm in the Forfar area of Angus in Scotland.
The farm had been under restriction since December last when vets found the disease in the original herd in Roscommon from where a group of 36 heifers had been exported to Scotland in May/June 2002.
A Department of Agriculture spokesman in Dublin said the heifers had been blood-tested for the disease, which causes the cows to abort their calves, before being exported to Scotland to conform with EU regulations.
All the animals had again tested negative when they were tested on arrival in Scotland and at 60-day post-import tests between July and September last year.
However, when the disease was identified in the Roscommon herd in December, the UK authorities were informed and restrictions were placed on five farms in Scotland where the animals were being kept.
All the animals were successfully traced as were animals which had close contacts with the imported Irish animals.
In an unrelated incident, Ireland was again the source of another brucellosis scare on a farm near Middlesbrough, in England. Three animals were involved in the scare and these had been imported with two other animals from a farm in Northern Ireland last September.
Four of the Northern Ireland imports had gone to the Middlesbrough farm and one had died there of an indeterminate cause and the fifth animal had gone to a farm in Scotland.
As in the imports from the Republic, the British authorities were alerted when there was a brucellosis breakdown on the Northern Ireland farm.
The UK's chief veterinary officer, Mr Jim Scudamore, who confirmed the outbreak in Scotland, said veterinary advice in England and Scotland was that any future risk of disease breakdown and spread should be contained by culling the imported animals and any offspring.
He confirmed he had ordered the slaughter of the animals in Scotland and the three animals on the English farm and said movement restrictions would remain in place on the farms involved.
He said there was no risk to public health from drinking pasteurised milk, cooked meat or contact with pasteurised animal products.
Brucellosis is a disease which can be passed on to humans normally after drinking contaminated unpasteurised dairy product or direct contact with infected material such as blood, urine or vaginal discharges.