Nearly 100 people became sick with norovirus aboard Royal Caribbean's Serenade of the Seas during a two-week cruise from San Diego to Miami, the Centers for Disease Control and Prevention confirmed.

The ship docked at PortMiami early Thursday morning.

Father and son caught in outbreak

Joshua Pettit and his father Bob boarded the Serenade of the Seas in San Diego on Sept. 19 for a 13-day cruise bound for Miami. Neither expected they would be among those affected by the highly contagious gastrointestinal illness.

"We started to notice an enhanced protocol at the buffet where they were serving you the food instead of you serving yourself," Joshua said.

But a few days after the ship's stop in Mexico, passengers began falling ill.

"Saturday night after dinner he started to feel nauseous. And it came out of him very suddenly," Joshua recalled of his father. "We were at a lounge. And he threw up before he could even get into the bathroom in the lounge. So it just comes that quick."

"It's very fast. Violently," Bob added, sitting next to his son.

Bob Pettit was given medication and ordered to quarantine in his stateroom.

Safety measures ramped up on board

While his father isolated, Joshua observed the ship's crew working to contain the outbreak.

"It's fairly normal to see someone always cleaning on a cruise ship," he said. "But now we're seeing four to six people fanatically wiping every handrail, chair, when someone would get up. Wiping the arms. They had been doing all the handles in the hallway. Tables, anything anybody touches, they're out in full force."

The CDC said 94 of the ship's 1,874 passengers — about 5 percent — contracted norovirus during the voyage. Four of 883 crew members were also affected.

Expert warns: "You're going to be losing fluids up and down"

FIU infectious disease professor Dr. Aileen Marty said outbreaks often begin when a single infected person brings the virus aboard.

"You're going to be losing fluids up and down. And that lead due to a situation where you can become severely dehydrated," she said. "And this becomes a big issue if you're immunocompromised, an infant, or very old."

CDC monitoring outbreak

Royal Caribbean reported the outbreak to the CDC's Vessel Sanitation Program on Sept. 28 and implemented its outbreak prevention and response plan, which includes isolating sick passengers, disinfecting common areas, and collecting stool samples for testing.

The VSP said it is remotely monitoring the situation and reviewing the ship's sanitation procedures. According to the program, an outbreak is defined as when 3 percent or more of a ship's passengers or crew report gastrointestinal illness symptoms.

Previous outbreak in July

This is not the first time Royal Caribbean has faced a norovirus outbreak this year. In July, more than 140 passengers and crew fell ill aboard the Navigator of the Seas during a weeklong cruise from Los Angeles with stops in Mexico.