By David Dolan and Ju-min Park
TOKYO (Reuters) - Another 39 people have tested positive for the coronavirus on the cruise ship Diamond Princess quarantined 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.
The epidemic originated in mainland China, where more than 1,100 people have now died from the virus.
About 3,700 people are on board the ship, which usually has a crew of 1,100 and a passenger capacity of 2,670.
The ministry said tests were being conducted for others deemed to need them and it would announce the results later.
The British-flagged Diamond Princess is managed by Princess Cruise Lines, one of the world's largest cruise lines and a unit of Carnival (NYSE:CCL) 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 who was infected had been handing out questionnaires checking the health of passengers and crew since Feb. 3, and had been following rules that require the wearing of 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," one passenger on the ship, who declined to be identified, told Reuters.
"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."
'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.
"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.
Mark Kortepeter, a professor of epidemiology at the University of Nebraska Medical Center, said while 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% 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.
The foreign ministry released a notice on Wednesday urging its nationals to consider delaying trips to China and for Japanese in China to return home.
Japan has sent four chartered flights to China's Hubei province, the epicenter of the outbreak, for its citizens there to return and plans a fifth.
(GRAPHIC: Tracking the spread of the coronavirus from China - https://graphics.reuters.com/CHINA-HEALTH-MAP/0100B59S39E/index.html)