World Champion Alessandro Ballan will also be absent on Saturday at Milano-Sanremo. Ballan's illness of the past few weeks will keep him on the sidelines a little longer.
"The exams performed at the Castelfranco Veneto hospital diagnosed a recent infection by the cytomegalovirus, which he probably caught about 15 days ago," said Lampre-NGC's medical consultant Carlo Guardascione.
"He must rest for 15-20 days. He will be able to begin training again when the sores completely disappear."
The cytomegalovirus is a common herpes-type virus that infects a majority of people during their lives but rarely causes obvious illness. Symptoms may include fever, swollen glands and feeling tired.
A disappointed Ballan said, "I'm very sad because I won't take part in Milano-Sanremo and my presence in the Classics of the North is compromised. Now I know why I wasn't well, I have to wait for a complete recovery.
"I can't say when I'll be back to racing, because it will all depend on the course of the infection."