A study of the potentially deadly pathogen E.coli 0157:H7 in sheep carcasses has found that 2.4 per cent of sheep in five processing plants carried it.
A similar study of pig carcasses by researcher Mary Lenahan of the Ashtown Food Research Centre, uncovered a rate of 0.24 per cent.
Details of these, the first surveys carried out on sheep and pigs in this country, were given yesterday to the Walsh Fellowship Seminar in the RDS.
Ms Lenahan said cattle were generally considered to be the main source of verocytotoxigenic E.coli, which can cause severe illness or death, especially in children and elderly people.
Recent evidence based on samples taken from humans who suffered from E.coli poisoning suggested that sheep and pigs were also carriers of the pathogen .
She said the principal aim of her study was to examine pig and lamb carcasses for E.coli 0157:H7.
"A one-year survey of E.coli 0157:H7 on pigs" was completed in December 2004. Of 1,680 porcine samples collected, it was isolated from four samples, or 0.24 per cent, she said.
Ms Lenahan added that all the porcine isolates contained genes typically associated with clinical illness in humans.
She said work was ongoing into the levels in sheep and to date, E.coli 0157: H7 was isolated from 23 or 2.4 per cent of the sheep samples.
Initial results, she told the seminar, indicated that Irish sheep and pigs were reservoirs and may be a potential source for this pathogen in humans.
Ms Lenahan, whose work was also supervised by the faculty of veterinary medicine in UCD, said cattle were thought to be the primary cause of outbreaks of poisoning in humans but her study indicated that this may not be the case.
"E.coli 0157:H7 naturally occurs in cattle and it could be passed in faeces or water or if in processing carcasses were contaminated," she said.
She said because the faeces of sheep contaminated the fleece, the spread of E.coli, especially in a damp country like Ireland, was more difficult to control.