TOKYO — As an extraordinary two-week quarantine of a cruise ship ends Wednesday in Japan, many scientists say it was a failed experiment: The ship seemed to become an incubator for a new virus instead of an isolation facility meant to prevent the worsening of an outbreak.
The viral illness that emerged last last year in central China has sickened tens of thousands of people, but the 542 cases confirmed among the ship’s 3,711 original passengers and crew are the most anywhere outside of China.
The Diamond Princess cruise ship is also the only place where health officials have seen the disease spread easily beyond China. The question is: Why?
The Japanese government has repeatedly defended the effectiveness of the quarantine. But some experts suggest it may have been less than rigorous.
In a possible sign of lax protocols, three Japanese health officials who helped conduct the quarantine checks on the ship were also infected.
“There are sometimes environments in which disease can spread in a more efficient way,” said Dr. Michael Ryan, executive director of the World Health Organization’s health emergencies program. Ryan said cruise ships in particular were known to occasionally accelerate spread.
“It’s an unfortunate event occurring on the ship and we trust that the authorities in Japan and the governments who are taking back people will be able to follow up those individuals in the appropriate way,” he said.
Japan’s health minister, Katsunobu Kato, told reporters Tuesday that all passengers who remained on the cruise ship have had samples taken and that those who tested negative would start getting off the vessel beginning Wednesday, when their required 14-day quarantine is scheduled to end.
“They all want to go home as early as possible, and we hope to assist them so that everyone can get home smoothly,” Kato said.
U.S. health officials on Tuesday told Americans who declined to come home on government-chartered flights over the weekend that they wouldn’t be allowed back into the country for at least 14 days after they had left the Diamond Princess.
“Obviously the quarantine hasn’t worked, and this ship has now become a source of infection,” said Dr. Nathalie MacDermott, an outbreak expert at King’s College London.