Who is on board?
The Diamond Princess, operated by a US company, departed from Yokohama on January 20th. Its 16-day itinerary featured stops in Kagoshima, Hong Kong, Vietnam, Taiwan, and Okinawa. The original passenger manifest included 2,666 travelers from 56 countries and regions and 1,045 crewmembers. The health authorities say about half are Japanese nationals.
Why can't they get off?
Health officials started screening passengers on Monday after an 80-year-old man who had been on board for six days before disembarking in Hong Kong was found to have been infected. Samples were taken of 273 people who were either displaying symptoms of the virus, including fever and cough, or had been in contact with such people or the man from Hong Kong. 31 sets of results have come in; so far, 10 have tested positive for the virus.
The officials say the infected travelers have been transported to hospitals and that their conditions are not serious.
The rest of the passengers will be kept on the ship for at least 14 days, which is believed to be how long the virus's incubation period lasts.

Who has been infected?
In a statement released on its website, the cruise operator said the infected hail from five countries and territories: three from Japan, three from Hong Kong, two from Australia, one from the US, and one from the Philippines, who is a crewmember.
NHK has also learned that four are in their 50s, four are in their 60s, one is in their 70s, and another is in their 80s.
Concerns are growing among those still on board.
"I'm worried because my wife's medicine is running out," a Japanese man in his 70s told NHK. He said the passengers were told to remain in their rooms and that he has no idea what he should do when his wife's supply runs out.
"It seems pretty calm on the surface but we're all worried. Many of us are old. Something has to be done as soon as possible."