The flanker damaged cartilage in his knee during Ulster's 43-6 Heineken Cup victory at Aironi on January 22.
The 25-year-old was unable to take part in a training camp in Limerick last week and it has now been confirmed he will miss the February 5 date in Rome.
"The knee did not respond to the rest period and Ferris was referred to the knee specialist who confirmed that while the injury did not require surgery, he would not be available for the Italy game," read a statement on Irish Rugby's official website.
"Ferris will continue with his rehabilitation and while there remains a doubt regarding his availability, he has not been ruled out for Ireland's clash with France on Sunday week (February 13)."
The Ulsterman joins fellow Lions Tommy Bowe, John Hayes, Jamie Heaslip, Shane Horgan, Rob Kearney, Jerry Flannery and Geordan Murphy on the casualty list while Ulster teammate Andrew Trimble is also ruled out.