Passengers wearing face masks are seen on the quarantined Diamond Princess cruise ship at the Daikaku Pier Cruise Terminal at Yokohama port, Japan, on Feb 12, 2020. (BEHROUZ MEHRI / AFP)

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

The Diamond Princess was placed in quarantine for two weeks upon arriving in Yokohama, south of Tokyo, on Feb 3, after a man who disembarked in Hong Kong was diagnosed with 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 quarantine officer 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

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

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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.

People testing positive for the virus are taken off the ship to hospital.

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.”

Members of the Japan Self-Defense Force attach a military vehicle to a gate of the quarantined Diamond Princess cruise ship at the Daikaku Pier Cruise Terminal at Yokohama port, Japan, on Feb 12, 2020. (BEHROUZ MEHRI / AFP)

'High risk'

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

Mark Kortepeter, a professor of epidemiology at the University of Nebraska Medical Center, said that although it was hard to reach conclusions based on limited information, the ship infections pointed to an “agent that is highly transmissible,” at least in enclosed environments.

“The infected quarantine officer probably indicates the high risk, even for individuals who are trying to protect themselves, because the virus is unforgiving and there is no room for error in use of personal protective equipment and hand hygiene,” he said. “A small number of virus particles is likely needed to infect, making it an efficient spreader.”

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

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.

An improvement in life for people on the boat came several days ago with the announcement they can receive packages sent to the address of the pier - a service that Rob Thomson, a New Zealander living in northern Japan, whose parents are on the boat, made prompt use of.

READ MORE: Japan finds 6 more coronavirus cases on cruise ship

“The one thing that they were missing were hot drinks during the day - they were getting coffee or tea at breakfast, but then during the day it was cold water or Coca-Cola or soft drinks ... and Dad was saying he’d like fresh fruit other than apples or oranges,” he said, adding that he placed an order Tuesday night.

“So I tried sending some grapes and strawberries and stuff. And apparently the fresh things have already been delivered to somebody on the dock.”

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Japan has sent four chartered flights to China’s Hubei province for its citizens there to return, and plans a fifth. The people who returned on the first flight will be released on Wednesday if they test negative for the virus, media said.