Three people who had close contact with the first patient in China with MERS - Middle East respiratory syndrome - were tracked down in Guangdong province on Monday, while 10 passengers on the bus to Huizhou with the infected South Korean man remain out of contact, according to the provincial Health and Family Planning Commission.

Seventy-seven people had close contact with the 44-year-old patient, surnamed Kim, in Guangdong. Of those, 67 have been quarantined. As of Monday, no abnormalities have been found.

Potential victims need to be kept under close observation for 14 days from the last day they had contact with the patient. The virus has an incubation period of two weeks, according to He Jianfeng, director in charge of infectious disease prevention and control at the Guangdong Provincial Center for Disease Control and Prevention.

Kim's father and sister are confirmed MERS patients. He got a fever after visiting his father, but flew from Seoul to Hong Kong anyway for a business trip on May 26 against the instructions of doctors, who told him to stay home. He traveled by bus to Huizhou, Guangdong, via Shenzhen, on the same day.

He was sent to the city's Central People's Hospital for treatment in isolation on Thursday, and MERS was confirmed on Friday.

Kim's vital signs were stable but he remained feverish on Monday, with the condition of his lungs worsening, the provincial Health and Family Planning Commission said.

He was put on a respirator for moderate acute respiratory distress syndrome, but was still conscious, according to Ling Yun, director of the intensive care unit at the hospital.

Fifty-four nurses are taking shifts every four hours to tend to the first MERS patient in China. None of them have shown symptoms of infection, thanks to protective measures.

Li Chunmei, a 32-year-old ICU nurse, has been at the hospital since Thursday to take care of Kim. She communicates with him mainly through gestures. She also writes simple Korean characters on paper - for example "hot" - and asks him to reply with a nod or shake of the head.

"At first I was afraid, but this is my job," said Li, who said her 5-year-old daughter calls every day and cries over the phone. She hasn't had a chance to meet her daughter to give an International Children's Day gift.

MERS is a respiratory illness caused by a new type of coronavirus similar to the virus causing SARS. There is no vaccine or treatment for the disease, which has a fatality rate of up to 41 percent.

"There is currently no proof that the virus can be spread from the second-generation patients to others. If the virus doesn't have great variation, MERS should be easy to control," Zhong Nan-shan, an expert who specializes in pandemics, told Guangzhou Daily.

xujingxi@chinadaily.com.cn