A Hong Kong man has tested positive for influenza A/H1N1, making him the second patient in Hong Kong confirmed to have been infected with the new strain of flu virus, health authorities said Wednesday.

    The patient, a 24-year-old local resident, recently traveled to San Francisco in the United States and returned to Hong Kong onboard the Cathy Pacific flight CX879 late Monday, said Thomas Tsang, controller of the Center for Health Protection.

    The patient went to see a doctor at a clinic at the airport and was suspected of being infected with influenza A/H1N1. He was then directly taken to the Princess Margaret Hospital from there, Tsang told reporters at a daily briefing.

    "The patient had no contact with the local community," he said.

    Tsang said the patient developed a fever as early as May 6, followed by a sore throat and coughing on May 8. The fever was mild when he arrived at the airport, which explained his passing the temperature screening without triggering an alarm.

    Nevertheless, the patient met three family members upon arriving at the Hong Kong International Airport before going to seek medical help, Tsang said.

    The patient was now in stable condition and showed no symptoms of pneumonia.

    Tsang said health authorities would have to quarantine the three family members as well as three crew members and six passengers onboard the flight CX879.

    The family members of the patient was now in quarantine. Authorities were tracking down the passengers who might have been in contact with the patient.

    The Hong Kong Special Administrative Region (HKSAR) government has informed the U.S. authorities of the new confirmed flu case, said Gabriel Leung, Under Secretary for Food and Health of the HKSAR government.

    Hong Kong reported the first confirmed flu case on May 1, which involved a 25-year-old Mexican man. It triggered higher flu alert level in Hong Kong and led to quarantine measures that affected hundreds of passengers, hotel guests, among others. All those put in quarantine, including the patient, have been discharged.