Authorities say 19 people aboard a cruise ship reported flu-like illnesses as they reached a Southern California port. The Los Angeles Fire Department says authorities were called early Sunday to evaluate patients after they fell ill on the Norwegian Joy cruise ship. It’s the second time in a week passengers were treated for illness after returning from a cruise on the same ship.

Authorities say the patients who were on a Mexican Riviera cruise, had minor medical complaints and none were taken to hospital.

“During Norwegian Joy’s Mexican Riviera sailing, a few guests on board experienced a stomach-related illness,” the cruise line said in a statement. “To mitigate any impact of this rare occurrence, we implemented stringent sanitation procedures. As always, we will continue to monitor this situation.”

Paramedics responded to the Norwegian Joy a week earlier after a report that passengers were ill and the LAFD said, six passengers arriving in Los Angeles from a Panama Canal voyage were treated for flu-like symptoms and were diagnosed with norovirus, Los Angeles Port Police Lt. Rosario Ferrara told CNN.

They were among 127 passengers and six crew members who reported being ill while aboard the ship, according to the US Centers for Disease Control and Prevention. The ill passengers were mostly suffering from diarrhea, the CDC said.

Norwegian Cruise Line employed special cleaning and disinfection procedures in response to the outbreak, the CDC said. Norovirus can cause diarrhea, vomiting, nausea and stomach pain.