Four new cases of BSE have been discovered in Irish cattle this week, according to the Department of Agriculture.
The infected animals were detected on farms in Cos Limerick, Clare, Roscommon and Leitrim.
This brings the total number of BSE cases for 2003 to 159, compared to 284 cases for the same period last year.
They were identified using both traditional passive surveillance (one case) and the active surveillance programme (three cases).
The Department said the underlying trend remains positive, and the increasing age profile of animals confirmed with the disease indicates that the enhanced controls introduced in 1996 and early 1997 are proving effective.
"The range of controls in place to protect consumers and to eradicate the disease continues to be rigorously enforced," the Department said, adding that all risk material is removed from every slaughtered animal.