JAPAN: lax standards, lax protocols, lax governance, lax reasoning, lax everything...

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 among people 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.

“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.

“There's no reason this (quarantine) should not have worked if it had been done properly," she said.

Other scientists said that passengers should have been removed from the ship from the beginning.

"Boats are notorious places for being incubators for viruses," said Arthur Caplan, a professor of bioethics at the New York University School of Medicine. "It's only morally justified to keep people on the boat if there are no other options."

Caplan said that a second quarantine was warranted, but that officials had done a poor job of explaining what would happen if their original plan failed.