BEIJING — Japan on Thursday reported its first case of a new coronavirus that has sickened at least 41 people in China, adding to concerns about the spread of the virus beyond China’s borders ahead of a major holiday.
Japan’s Health Ministry said that a Chinese man in his 30s tested positive for the mysterious pneumonia-like coronavirus. The man, a resident of Kanagawa Prefecture, just south of Tokyo, returned to Japan on Jan. 6 after traveling to the central Chinese city of Wuhan, the epicenter of the outbreak. The man, who came down with a fever on Jan. 3, was hospitalized on Friday but was discharged five days later because he had recovered, according to the Health Ministry.
The World Health Organization said it was highly likely that the virus had spread from a seafood market in Wuhan that also sells live birds and other animals. But Japan’s Health Ministry said the patient had not visited any seafood markets in China, adding that “it is possible that the patient had close contact with an unknown patient with lung inflammation while in China.”
Malik Peiris, a public health virologist at the University of Hong Kong, said, “If that was the case, that there had been no direct exposure to animals, then that is very concerning, for sure.”
It was the second confirmed case of the new coronavirus reported outside of China in the last week. In Thailand on Monday, the authorities detected the virus in a 61-year-old Chinese woman who was visiting from Wuhan, the capital of the central Chinese province of Hubei.
Dr. Sopon Iamsirithaworn, director of the communicable diseases division at Thailand’s Ministry of Public Health, said the woman had not visited the Wuhan seafood market, and had come down with a fever on Jan. 5. However, the doctor said, the woman visited a different smaller market in Wuhan, in which live and freshly slaughtered animals were also sold.
The woman is in good health now, according to Dr. Suthat Chottanapund, a senior official in the disease control department of Thailand’s Public Health Ministry. But, he said, the health authorities were waiting for laboratory results to confirm that the woman is free of the coronavirus before discharging her. She said that she wanted to do some sightseeing after she leaves the hospital, he said.
The revelation that neither the patient in Japan nor Thailand had visited the Huanan Seafood Market, to which most of the cases have been linked, is a troubling sign that the outbreak could be spreading in Wuhan. The market was shut down and disinfected on Jan. 1, but new cases have appeared since, suggesting the virus has not been eradicated.
Concerns have grown across the region since the Chinese health authorities announced the discovery of the new mysterious virus that has caused dozens of people in Wuhan to fall ill with a pneumonia-like illness. The city’s health commission said on Wednesday that the risk of human-to-human transmission is low but possible. Officials also said they detected the first cluster of the virus involving members of a single family.
The new virus has stirred memories in China of the 2003 outbreak of severe acute respiratory syndrome, or SARS. That virus, which is believed to have jumped to humans from animals at markets, originated in China and killed more than 800 people worldwide in 2002 and 2003. At the time, the Chinese government tried to cover up the problem, resulting in a backlash among its people. While flu experts have said the Chinese government is trying to be more transparent now, many in China are skeptical.
The local authorities in Wuhan and the W.H.O. have reiterated for weeks that no cases of human-to-human transmission have been confirmed.
Last week, researchers in China said they had “initially identified” a new coronavirus as the pathogen behind the mysterious new respiratory illness. Of the 41 cases diagnosed in Wuhan, the majority of patients were middle-age and older men, the city’s health commission said on Wednesday. Last weekend, the local authorities said one 61-year-old man died after contracting the virus.
The most recent case in China was detected on Jan. 3. The minimum incubation period for some viral infections is 15 days, suggesting that it could be a few more days before the authorities are able to determine the full extent of the outbreak.
That timeline has fueled concerns among governments across the region, especially ahead of the Lunar New Year holiday, which begins next week. Hundreds of millions of people in China are expected to travel during the holiday. Thailand expects more than 300,000 Chinese visitors during the holiday, according to local tourism officials.
Hong Kong, Singapore, Thailand and South Korea have taken precautionary measures, quarantining patients with flu-like symptoms and increasing temperature screenings at their airports. Japan said it was investigating who the patient there had been in contact with since he returned from China and has asked people who experience symptoms to report them.
While the new coronavirus appears to be less virulent and deadly than SARS, many questions remain, including the source of the virus and its transmission route. Infectious disease experts say the source is very likely to be a mammal because coronaviruses spread easily from mammals to humans.
Coronaviruses are a large family of viruses that infect animals and people. Symptoms of different coronaviruses can include those that resemble the common cold, influenza or pneumonia.
“There’s no need to panic but I think there needs to be an urgency to address these questions,” said Dr. Peiris of the University of Hong Kong. “The problem is that most of these animals are illegally sold, so that might not be so easy to do.”
Dr. Peiris said he was encouraged that there were no cases of hospital workers falling ill, reducing the likelihood of a widespread outbreak within the community, as there had been with SARS.
Guan Yi, a professor of infectious diseases at the University of Hong Kong, said he was also reassured that the Wuhan government had not reported any new cases in recent days.
“If there are no new cases in the next few days, the outbreak is over,” said Dr. Guan, who was part of a team that successfully identified the coronavirus that caused SARS.
Eimi Yamamitsu contributed reporting from Tokyo, and Hannah Beech and Muktita Suhartono from Bangkok. Elsie Chen contributed research from Beijing.