SAN DIEGO (AP) — More than 100 passengers have contracted the highly contagious norovirus on a ship that is touring the California coast. But the cruise line says it has no plans to end the voyage early.

Some 104 passengers and 25 crew members on the Crown Princess had been infected by the cruise's fifth day, but fewer than 15 were still complaining of the gastrointestinal symptoms that come with the virus, Princess Cruises spokeswoman Karen Candy said Thursday.

Fifty people have been quarantined in their cabins because they could still be contagious.

The Crown Princess is on a seven-day cruise from Los Angeles that included stops in San Francisco and Santa Barbara. The ship was in San Diego on Thursday and is scheduled to return to LA on Saturday.

Passengers can leave the cruise voluntarily at any of the planned stops, Candy said.

Cruise lines are required to report to the federal Centers for Disease Control and Prevention when an outbreak affects more than 2 percent of passengers. About 3 percent of the 3,100 passengers on the Crown Princess were afflicted, and Princess Cruises alerted the agency.

The ship was getting a thorough cleaning while docked in San Diego and would get an even more intensive one at the end of the journey.

In January, a Royal Caribbean cruise with similar numbers aboard canceled its voyage and returned to New Jersey after nearly 700 people contracted norovirus in one of the worst such outbreaks in 20 years.