Hong Kong yesterday recorded its first two "preliminary positive" cases of the contagious Wuhan pneumonia virus, which has so far killed 17 people.

This came as authorities in Wuhan last night enacted an emergency law requiring all citizens to wear face masks in public places.

The deadly virus, which has infected more than 535 people in China, has now spread outside Asia to the United States.

Four family members of the first case - a Wuhan man, 39 - are being traced after they left on a Cebu Airlines flight yesterday morning for Manila.

The second case involves a 56-year-old Hong Kong resident who visited Wuhan.

The Wuhan male tourist arrived in the SAR on an express rail from Shenzhenbei on Tuesday night. He was discovered to have a fever and stuffy nose as he crossed health control points at the West Kowloon station, Secretary for Food and Health Sophia Chan Siu-chee said last night.

He was immediately sent to Queen Elizabeth Hospital in Jordan for isolation. Chan said the man tested positive to the Wuhan novel coronavirus in an initial test and is pending further tests, with the results being announced today.

The man - in stable and conscious condition - was last night transferred by ambulance to Princess Margaret Hospital in Kwai Chung, which has been a designated infectious disease center since 1975.

He was seen wearing a surgical mask while sitting upright on a mobile bed as about eight medical workers in full protective gear - including coats, N95 masks, caps and goggles - accompanied him out of the isolation ward of Queen Elizabeth Hospital.

Sources said a second "preliminary positive" patient had been admitted to Prince of Wales Hospital in Sha Tin and then transferred to Princess Margaret for isolation. He was in stable condition.

The Hong Kong man, 56, visited relatives in Wuhan from January 10 and returned to Hong Kong on Sunday, when he fell sick and attended Prince of Wales Hospital. But an X-ray scan at the time showed he had no symptoms of pneumonia and he was not hospitalized.

He attended the hospital again on Tuesday, when an X-ray scan showed there were shadows on his lungs.

Sources said the man, who lives alone in Oceanaire in Ma On Shan, was tested positive to the Wuhan virus in an initial test.

Speaking on the first case, Chan said: "The man arrived in Hong Kong with four family members, who did not show any symptoms, and stayed in the Empire Hotel Kowloon in Tsim Sha Tsui for one night before they left Hong Kong on Cebu Pacific flight 5J111."

Director of Health Constance Chan Hon-yee said the man on Tuesday afternoon took express rail train G1015 from Wuhan to Shenzhenbei. He sat in seat 10D in the third carriage.

At 7.35pm on the same day, he took train G5607 from Shenzhebe, sitting in 2D in the second carriage, and arrived in Hong Kong at 7.54pm.

Chan said the Department of Health has set up a hotline at 2125-1122 calling for citizens who took the same express rail as the man to report to the government. She said close contacts - those sitting in the same row and two rows in front of and behind the man - would immediately be put into isolation camps. Other passengers in the same carriage will be placed under medical observation. Asked why the man's family was not put under isolation, she said when the case became a "preliminary positive" one, his family had already left the SAR.

This came a week after the government stepped up border health controls requiring travelers arriving at Hong Kong International Airport from Wuhan by direct flights to fill out health declaration forms. But the same policy was not implemented at the West Kowloon station. "Discovery of the case showed our strict border health control, including temperature check and the reporting system, can effectively detect patients," said Chan.

Earlier yesterday, Chan said camps were ready to be turned into sites of isolation for quarantine of confirmed patients' close contacts, adding such sites could be used within hours of notice. Sources said the two campsites are Lei Yue Mun Park in Chai Wan and Lady MacLehose Holiday Village in Sai Kung, both of which were in 2003.

Meanwhile, the death toll of the Wuhan new virus rose to nine, infected over 473 and already reached the US which could mutate and spread, China warned yesterday.

Mainland health authorities yesterday confirmed the source of the new coronavirus to be wild animals, most likely to be Rhizomys, illegally sold at Huanan seafood wholesale market in Wuhan, where most of the first batch of 27 patients worked or frequently visited.

It is understood that no children have been infected so far.

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