Finally, the captain confirmed on the loudspeaker that among their number was a woman who worked as a lab supervisor at Texas Health Presbyterian Hospital in Dallas. She had processed clinical samples from Thomas Eric Duncan, a Liberian man who was the first person diagnosed with Ebola in the United States. The 42-year-old died on October 8, four days before the ship sailed.
The lab supervisor, and her husband, were voluntarily quarantined in their cabin as fear spread on the ship, which arrived back in Galveston earlier today NZ time.
A sample taken from the woman had since tested negative for Ebola.
Jon Malone, a passenger, said there was "utter panic", adding: "People are scared. I've seen people crying. You're using the same buffet line as someone else, the same waiters, the folks that clean the state rooms.
"It's really difficult to control any type of virus that's on a cruise ship. It's like a floating petri dish. "
Outside his room on the 11th floor, Jeremy Malone saw up to 40 workers in masks with cleaning fluids.
As word of an Ebola scare spread, so many passengers tried to call home that their mobile signals failed, and the internet crashed.
One passenger, who gave his name as Michael, was able to get through to CNN by telephone. He said: "Obviously our concern is where is this person on the ship and what kind of set-up do they have to care for them? I can't imagine it's a completely quarantined area."
The passenger first realised something was wrong when he looked at a map of the ship's course on his television. He said: "We were supposed to be put into a port and I noticed that we were pulling away from the port. The captain finally came on and said we couldn't get permission to port. That's when everything hit the fan here and we realised we were quarantined."
The lab supervisor boarded the Carnival Magic, which carries 3690 passengers and up to 1367 crew, in Galveston on October 12.
She had not been placed under any travel restrictions by the hospital or the US Centres for Disease Control and Prevention (CDC). Both have been criticised for not telling health workers who had contact with Duncan to stay home. The woman on the ship was only required to self-monitor her temperature daily to see if she developed a fever.
After seeing news reports about two nurses who worked at the hospital - Nina Pham, 26, and Amber Vinson, 29 - being diagnosed with Ebola she decided to report herself to the captain, and self-quarantine by staying in her cabin.
The ship then applied to drop her off in Belize so she could be flown back to Texas, but the Belize Government refused. Prime Minister Dean Barrow refused a personal appeal from John Kerry, the US Secretary of State, to send a helicopter to pick her up from the Carnival Magic and take her to a plane waiting at an airport in Belize.
But all the other passengers, except the woman and her husband, were allowed to disembark in Belize for their scheduled stop.
The Texas Health Presbyterian Hospital lab supervisor and her husband were the first passengers to disembark in Glaveston, and were both screened by CDC doctors, local reporter Larry Seward said on Twitter, citing an executive with Carnival Cruise Lines.
The Carnival Magic then sailed on to Mexico where it was scheduled to dock in the port of Cozumel.
Carnival spokesman Jim Berra told the Los Angeles Times that a helicopter picked up a blood sample and the sample tested negative for Ebola.
Carnival offered compensation of US$200 ($253) per passenger to those on board, and a 50 per cent discount on future cruises, as an apology for missing the Mexican stop.
A spokesman said: "We greatly regret that this situation, which was completely beyond our control, precluded the ship from making its scheduled visit to Cozumel and the resulting disappointment it has caused our guests."
- with additional reporting AP
