A County Tipperary man claims he contracted brucellosis while working as a plumber in meat rendering plants.
Matthew Ryan of Bianconi Drive, Clonmel is suing a number of meat plants and his employer.
The 67 year old was diagnosed with the disease in 2006.
Mister Ryan is now taking a High Court action against his former employer, Cahir based E. Buttimer and Company as well as National By-Products Ltd and Anglo Irish Beef Processors.
The defendants deny the claim and plead contributory negligence.
The hearing is continuing before Mr Justice Iarfhlaith O'Neill.