Junior Agriculture Minister Tony Killeen confirmed that the Department of Agriculture had identified equine piroplasmosis in several thoroughbreds at a horse property at Dunshaughlin in County Meath.
The country's report to the World Organisation for Animal Health, filed yesterday, said there were 28 cases.
The tick-borne protozoan disease affects horses, mules, donkeys and zebra.
It is caused by two blood parasites, Theleria equi and Babesia caballi, and gives rise to anaemia and jaundice in affected animals.
The disease is not readily contagious and cannot affect people.
Movement restrictions have been placed on the property and inquiries are under way to established the origin of the disease and the extent of its spread, if any.
"The department has been in contact with industry representatives who have been informed of the situation," Killeen said.
"A meeting with industry representatives has been arranged to discuss the implications for animal movement and the measures appropriate to address the threat posed by the disease."
Equine piroplasmosis has been a notifiable disease in Ireland since July 2009.
It has not been officially reported in Ireland before, although it is understood that a previous incursion did take place. The disease is present in Mediterranean countries.
A small outbreak in Florida last year represented the first cases of the disease in that country in 20 years. It is thought the disease arrived in a horse from Mexico. Another case was reported in the US, in a quarter horse in Missouri, in June.
While equine piroplasmosis is a tick-borne disease, it can also be spread by contaminated needles.