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BEIJING — As China prepares for the impending Lunar New Year travel boom, health authorities reported the country's first death from a viral pneumonia Saturday, heightening concerns over a possible flare-up similar to that of the early-2000s SARS outbreak.

A 61-year-old man who had been hospitalized after suffering shortness of breath and severe pneumonia in the central Chinese city of Wuhan died Thursday, authorities said.

The Wuhan Municipal Health Commission said that 41 people are under hospital quarantine with suspected infection of the mystery virus, seven of whom are critically ill.

They said that 739 incidents of close contact were under medical surveillance, an increase from the previous 163. 419 of those cases involve medical staff.

The U.S. Centers for Disease Control and Prevention (CDC) has issued an alert for “a pneumonia outbreak of unknown cause” in China, urging Americans to “avoid animals — alive or dead — and animal markets, avoid contacts with sick people and wash hands often with soap and water.”

The man who died was a regular buyer at a seafood market in Wuhan, the health authority said.

Treatments did not improve his symptoms after he was admitted to hospital and he died on the evening of Jan. 9 when his heart failed. He tested positive for the virus, it added.

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A preliminary investigation identified the respiratory disease as a new type of coronavirus, Chinese state media reported Thursday, citing scientists handling the probe.

Beijing expects some 3 billion passenger trips, with 400 million by train, as the country celebrates the new year. Some 7 million Chinese tourists are also expected to travel overseas.

In anticipation of a 40-day period of celebration, which begins this year on Jan. 25, the transport ministry said it plans additional measures to disinfect trains, planes and buses in order to prevent the transmission of diseases.

Wuhan is a travel hub for the country's center. The city's mystery flu has stoked fears of an outbreak not seen since the severe acute respiratory syndrome (SARS) epidemic that infected more than 8,400 people worldwide in 2002 and 2003.

More than 800 people died in the outbreak, which originated from animal markets in southern China.

China has said the cause of the recent illness remains unknown, but has sought to dismiss speculation that it could be a reappearance of SARS.

Dr. David Hui Shu-cheong, a respiratory expert and chairman of the Department of Medicine and Therapeutics at Chinese University of Hong Kong, told NBC News he felt that "the risk to Hong Kong and other parts of the world is low” as long as health authorities in Wuhan can contain it there.

"They are much better than in 2003 in handling severe infections in terms of transparency and timeliness,” he added.

Coronaviruses are a large family of viruses, some of which cause the common cold. Others found in bats, camels and other animals have evolved into more severe illnesses.

The World Health Organization has described its symptoms as “mainly fever, with a few patients having difficulty in breathing, and chest radiographs showing invasive lesions of both lungs.”

“I think the current situation is much different than SARS in that health authorities in Wuhan have been providing regular updates,” said Dr. Jennifer Nuzzo, an epidemiologist and senior scholar at the John Hopkins Center for Health Security.

“It is reassuring that after a month the total number of cases is fairly limited and the absence of healthcare worker infections supports the idea that there hasn't been sustained human to human transmission,” she added.

“But we are obviously concerned about the potential for this to change and that is why this situation warrants the attention it has been getting."