Around 200 passengers were hit by gastroenteritis during a cruise on one of the world's largest ships, Royal Caribbean's Ovation of the Seas.
The ship docked in Hobart, Tasmania on Tuesday and had been sailing for two weeks, arriving in Australia from Singapore.
Footage emerged of crew members wearing industrial cleaning suits spraying the hallways of the cruise ship after a gastro outbreak.
In a statement, Royal Caribbean said 195 people received over-the-counter medication for the illness.
"Those affected by the short-lived illness were treated by our ship's doctors with over-the-counter medication, and we hope all our guests feel better quickly," it said.
"Meanwhile, we're taking steps like intensive sanitary procedures to minimise the risk of any further issues."
One passenger wrote on Facebook: "I'm on here now and basically a sitting duck with people in both cabins either side not well with the gastro.
"They are doing everything perfectly to avoid further sickness.
"I could hear them last night doing this spraying outside my cabin."