TOKYO - Another 39 people have tested positive for the coronavirus on the quarantined Diamond Princess cruise ship in Japan as well as one quarantine officer, bringing the total to 175, the health ministry said on Wednesday.

The Diamond Princess was placed in quarantine for 2 weeks upon arriving in Yokohama, south of Tokyo, on Feb. 3, after a man who disembarked in Hong Kong was diagnosed with the virus. The epidemic originated in mainland China, where more than 1,100 people have now died from the virus.

About 3,700 people are aboard the ship, which usually has a crew of 1,100 and a passenger capacity of 2,670.

The ministry said tests are being conducted for others who are deemed to need them and it will announce the results later.

The UK-flagged Diamond Princess is managed by Princess Cruise Lines, one of the world's largest cruise lines and a unit of Carnival Corp.

Kyodo news agency, citing the health ministry, said that of the 39 cases, 10 were crew and 29 were passengers.

Ten were Japanese nationals and the others were from 11 countries including the United States and China. Four were in serious condition, Health Minister Katsunobu Kato said.

The quarantine officer had been handing out questionnaires checking the health of passengers and crew since Feb. 3, and had been following rules that require wearing a mask and gloves but not a full protective suit, according to the Nikkei business daily, quoting the health ministry.

"It's terrible about the quarantine officer. I wonder if they (the officer) are from the first batch that came aboard," one 43-year-old passenger on the ship told Reuters, declining to be identified.

"The ones who came to our room to do the initial screening had gloves and surgical masks, while the ones who came to do the actual virus test also had full gowns and full face masks."

A health ministry official had no immediate comment, but Nikkei said the ministry was checking into the officer's contacts with colleagues and family members.

"There are lots of ways to get infected even if you're wearing a mask. Hand hygiene, touching the mask and then not washing hands, wearing a mask but touching your eyes with contaminated hands ... It happens," said David Fisman, an epidemiologist at the University of Toronto.

"Personal protective items reduce risk, they don't eliminate it," he said.

The government was considering allowing elderly and those with chronic illnesses to disembark before the Feb. 19 target date for ending the quarantine, some media reported, but added it would take time to figure out where they could be sent.

As of last week, about 80 percent of the passengers were aged 60 or over, with 215 in their 80s and 11 in the 90s, the English-language Japan Times newspaper reported.