A cruise ship that docked in California Sunday that had 172 people fall victim to the highly contagious norovirus during a planned month-long trip is now back at sea.

The sick made up a significant portion of the 4,100 people aboard Princess Cruises’ Crown Princess, which had embarked on a voyage from Los Angeles to Hawaii to Tahiti. Those 172 individuals had begun sowing signs of gastrointestinal sickness just a few days into the trip, and they were treated on board the ship, according to a CBS New report, which quoted the Centers for Disease Control and Prevention (CDC).

The ship was to undergo a deep cleaning while at the terminal before embarking on its next trip to the Mexican Riviera, according to a company spokeswoman. It departed last night, according to news reports.

The symptoms of norovirus including fever, body aches, diarrhea, and vomiting, and most people take about three days to recover. The sickened individuals weren’t all sick at the same time, and healthy passengers were concerned about contracting the virus.

Passengers said the captain kept them informed on the number of ill, and that figure seemed to drop with each day, according to the report. It dropped from about 90 to 40 in a couple days, a passenger said.

The ill passengers were confined to their cabins and had to use room service each day. The rooms were sterilized afterward.

The crew roped off the buffet and had staff personally serve the passengers to limit the risk of spreading the virus.

Eventually, the ship returned to San Pedro in California at day later than originally planned due to the fact that a crew member had to go to a nearby island due to a medical emergency.

Passengers were credited with the lost day. By 9 p.m. Sunday, the ship had been cleaned and was on its way to Mexico.

In April, 129 people came down with the norovirus during a seven-day cruise off California.