Cleaning crews spent much of Monday and Tuesday scrubbing down a cruise ship docked in Baltimore and the port's cruise terminal after a nasty little virus treated more than 200 passengers and crew members to bouts of diarrhea and vomiting.
The newly cleaned Grandeur of the Seas was expected to embark again from Baltimore as scheduled Tuesday evening, a Royal Caribbean spokeswoman said.
The norovirus, which also broke out on the Grandeur twice last year, can spread quickly in confined spaces like cruise ships through contaminated food and water — think the buffet line — and can cling to hard surfaces until picked up by its next unwilling host.
It can also be hard to kill, considering its natural life cycle requires it to survive the acidity of the human stomach, said Kellogg Schwab, a Johns Hopkins University Bloomberg School of Public Health professor who has studied the virus since 1989. It's often spread by people who fail to wash their hands after using the bathroom, he said.
"Hand washing is a good first step, and strict adherence to that by everybody helps everyone," said Schwab, who is also director of Johns Hopkins Water Institute. "We're all part of this problem. We're all part of the solution, too."
The Grandeur has suffered a string of difficulties in recent years. In May 2013, a fire broke out on board, disrupting the vacations of more than 2,000 passengers and sending the ship into dry dock for six weeks of repairs.
Last year, two norovirus outbreaks occurred on the ship. More than 100 passengers fell ill on a cruise that departed March 28 from Baltimore, and nearly 100 passengers fell ill on a cruise that departed Baltimore on April 5. Neither of those cruises was cut short.
The most recent outbreak affected 193 passengers, or nearly 10 percent of those on board, and nine crew members, said Cynthia Martinez, the Royal Caribbean spokeswoman. Those who fell sick from the virus had "responded well to over-the-counter medication administered onboard the ship," Martinez said.
Another passenger on the ship experienced an unrelated medical emergency on Sunday, which forced the ship to speed its return to Baltimore, where it arrived about 1 p.m. Monday, Martinez said. The 10-night Caribbean cruise departed Jan. 24 and was originally scheduled to return to Baltimore on Tuesday.
Norovirus, which is not related to the flu, is the leading cause of food-borne illness in the United States, according to the Centers for Disease Control and Prevention. More than 80 percent of the nation's outbreaks occur from November to April.
Schwab said it's difficult to know how the virus was able to spread this trip or if the repeated outbreaks on the same ship reflect on how it is cleaned. The outbreaks could have nothing to do with Royal Caribbean and more to do with the hygiene of passengers.
"This could be coming from different sources," he said. "How do you get human behavior to change? How do you reinforce washing your hands, which your mother told you was important?"
Two environmental health officials with the CDC Vessel Sanitation Program and two epidemiologists first boarded the Grandeur in Jamaica on Jan. 30 to conduct an investigation and collect samples, after receiving reports of an outbreak.
Royal Caribbean said the Grandeur was to receive a "ship-wide cleaning and disinfection" after the passengers disembarked in Baltimore. It said the terminal also would be sanitized.
Hank Lambert, CEO of Pure Bioscience, a company that produces a cleaning spray to deal with food-borne illnesses, including norovirus on cruise ships, said the cleaning would likely entail a complete scrub down of "everything from hand rails to elevator buttons to the food service lines," among other surfaces.
"Any hard surface that would be a high-touch surface on the ship, including in the food service areas, would need to be sprayed down, disinfected, decontaminated," he said.
Schwab said the virus also can live in softer materials like carpets and fabrics, so those would have to be cleaned as well.
Martinez said all of the Grandeur's passengers received an "onboard credit" for missing a port call in Labadee, Haiti, with the amount of the credit varying based on the kind of room they were staying in. They also all received a "future cruise certificate equal to one day of the cruise fare they paid," she said.
Passengers arriving to the ship Tuesday for a 10-day cruise to the Caribbean were assisted by staff in rescheduling if they felt uncomfortable boarding the ship out of concern for their health, Martinez said.
Last year, the CDC investigated nine norovirus outbreaks on cruise ships, including the two on the Grandeur. This outbreak on the Grandeur was the first reported in 2015.