Sydney, Australia (My Sportsbook) - Australian swimmer Eamon Sullivan, a three-time Olympic medalist, pulled out of the world championships, scheduled for later this month in Rome due to a virus.

Sullivan, who won a silver medal in the 100-meter freestyle in Beijing last summer and was a part of two medal-winning relays, has been in Europe for the last six weeks, has struggled to overcome a virus that has hampered his training and race preparation, according to Swimming Australia.

The organization said Sullivan will return to Australia this week for further diagnosis.

Fellow Aussie Hayden Stoeckel also withdrew due to a shoulder injury. The 24- year-old backstroker will stay in Adelaide for treatment.

"To lose two Olympic medalists this close to the start of the World Championships is pretty disappointing, but we've taken this decision with London 2012 in mind," Swimming Australia coach Alan Thompson said.

Sullivan was to swim in the 50m and 100m freestyle, and Stoeckel was set to swim the 50m, 100m and 200m backstroke in Rome.

"While it's disappointing the guys won't be with us in Rome, the break will give them every opportunity to get over their illness and injury and regain full fitness as quickly as possible," added Thompson.

The organization said both Sullivan and Stoeckel won't be replaced on the Australian World Championships team.