Investigators from the Centers for Disease Control and Prevention joined the last leg of the Carnival Liberty’s cruise in St. Maarten on Thursday to probe a gastrointestinal outbreak that hit more than 600 passengers and crew over the past 13 days.
The outbreak on the 110-ton cruise ship, which was slated to arrive in Fort Lauderdale on Sunday, is among the largest in recent memory, according to the CDC, reports the Miami Herald.
The 2,804-passenger Liberty left a port near Rome on Nov. 3 for a 16-day trans-Atlantic voyage, and by the next day, guests began showing symptoms of diarrhea and vomiting. Those symptoms match Norovirus, a highly contagious virus that causes gastroenteritis, although the virus hasn’t been confirmed on the Liberty.
Jennifer de la Cruz, a Carnival Cruise Lines spokeswoman, said the Miami-based cruise giant hasn’t nailed down the origin of the outbreak. However, she added, two passengers acknowledged getting sick in Rome prior to getting on the cruise.
”It may have been those two who were the source, but that’s speculation,” she said.
Norovirus is sometimes called ”the 24-hour bug,” but symptoms can drag on three days.
”A lot of people have been ill, but very, very few people are ill now, so it appears to have run its course,” said David Forney, chief of the CDC’s vessel sanitation program in Atlanta.
According to Forney, the CDC team sailing on the Liberty includes two medical epidemiologists, who are examining medical records, symptoms and patients’ profiles. A third member — an environmental health officer — is checking ship records on how potable water and food have been handled to ensure the ship is adhering to protocol.
In an unusual step, Carnival is cutting short the ship’s next cruise to have two extra days in port in Fort Lauderdale to give the Liberty a thorough cleaning.
Forney, who is sending additional CDC staffers to monitor that cleaning, said the cruise line plans to deploy some 55 additional contract cleaners, who with fogging machines and wipes will scrub all the cabins and public spaces on the ship with bleach and another sanitizing material.
”Each cabin will probably be cleaned four to five times,” Forney said.
The special treatment is called for because of the exceptionally large number of people who got sick, he said. Some 506 passengers and 137 crew members had come down with the ailment by Wednesday, by CDC count. That amounts to 18 percent of the passengers and nearly 12 percent of the crew.
Forney said the high numbers, both in totals and percentages, likely stem from the ship being on an unusually long voyage: a trip across the Atlantic to reposition the vessel from its summer itinerary in Europe to the Caribbean.
”With so many people and for so long, the opportunity to contaminate surfaces, to get other people exposed increases,” he said.
The virus can spread by contact between people or by touching something a sick person has touched, such as stair rails, elevator buttons and door handles.
Both the CDC and Carnival said the outbreak appears to be on the wane. ”No new crew cases have been reported in the past two days,” de la Cruz said Thursday. “And we have only four new guest cases and only 10 guests that are still in isolation with symptoms.”
In addition to keeping sick guests in isolation, Carnival has stepped up disinfecting the ship and broadcast announcements to encourage passengers to wash their hands — a key step in preventing infection.
”We really ratcheted up cleaning and sanitation to prevent the spread by common surfaces,” de la Cruz said. “We stopped the self-service buffet and instead had the crew serving food with utensils.”
The ship was originally slated to go on a six-day, round-trip voyage through the Caribbean departing Sunday. Carnival said the abbreviated four-day version of the cruise leaving Nov. 21 will stop in Key West and Cozumel, Mexico. Passengers who opt to take it will get a 50 percent refund and a 50 percent discount on a future cruise, Carnival said. Passengers can also choose to take a full refund.
Gastrointestinal bugs are common both on land and at sea. Earlier this month, a Royal Caribbean Cruises ship, the Adventure of the Seas, reported some 130 passengers and crew were sick with gastrointestinal symptoms on a cruise Nov. 5-12 from San Juan.
Cruise lines argue they often get disproportionately tarred because they monitor and report illness outbreaks, while other public spots like hotels don’t. ”If you really look at the presence of Norovirus, there is way more [of it] all over the globe,” says Royal Caribbean spokesman Michael Sheehan.