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HANOI, May 31 (Reuters) - A 23-year-old Vietnamese student who returned home from the United States has been confirmed as having the H1N1 influenza virus, the first case in the Southeast Asian country, a Vietnamese doctor said on Sunday.

"The patient is still strong and he looks normal, but we can confirm that he is the first case of an H1N1 infection in Vietnam," the doctor from the Pasteur Institute in Ho Chi Minh City said, citing laboratory test results. The Tuoi Tre newspaper reported on Sunday that the student started developing a slight fever on May 25 after returning to the southern city from America and he was hospitalised on May 29.

Initial tests at the city's tropical diseases hospital were positive for H1N1. The Pasteur Institute, a medical research centre, cross-tested his samples and re-confirmed the presence of the virus, the doctor, who declined to be identified, told Reuters.

The newspaper and the doctor did not say where the student had been in the United States or which airline he took back to Vietnam.

Vietnam -- which has grappled with the more deadly H5N1 bird flu virus in recent years -- requires any suspected H1N1 cases to be isolated for seven days.

The H1N1 virus has infected at least 15,600 people globally and killed 113, most of them in Mexico. [ID:nLT496139].

(Reporting by Ho Binh Minh; Writing by John Ruwitch, Editing by Dean Yates)

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