LOS ANGELES — The Centers for Disease Control and Prevention says 172 people on a cruise ship that arrived in California on Sunday have fallen ill with the highly contagious norovirus during a nearly monthlong trip.

The Crown Princess has more than 4,100 people on board and was met by CDC staff after arriving in San Pedro in Los Angeles. CDC staff will conduct testing and evaluate the response.

Princess Cruises “enacted our stringent disinfecting protocols” developed in consultation with the CDC and planned to do a deep cleaning of the ship and terminal in Los Angeles before departing Sunday night for a weeklong cruise through the Mexican Riviera, said spokeswoman Susan Lomax.

In April, 129 people on the same ship contracted norovirus during a seven-day cruise off the California coast. Lomax said the ship went through the same stringent disinfecting process after it docked.

“As it is the cold and flu season, when the stomach flu circulates on land, we encourage all of our guests to be diligent in following the widely accepted practices of frequent hand washing with soap and water and the use of hand sanitizers,” Lomax said.

Symptoms of norovirus include vomiting, diarrhea, fever and body aches. According to the CDC, most people recover within three days.

The 28-day cruise visited Hawaii and Tahiti.