Federal health officials say the first cruise ship to dock in Portland, Maine, this season is under surveillance for norovirus.

The Centers for Disease Control and Prevention says 27 percent of the passengers aboard the Balmoral — operated by the Fred Olsen Cruises — have gotten sick since the cruise began April 16.

The ship and all aboard have since left Portland, according to police Lieutenant Robert Doherty.

The CDC reports that 252 of the 919 passengers on the Balmoral have fallen ill, as well as eight crew members.

Fred Olsen Cruises did not immediately return a call seeking comment.

So far this year, there have been 10 outbreaks of norovirus on cruise ships, according to the CDC.