GUANGZHOU - A man died of lethal flu virus known as A/H1N1 in south China's Guangdong Province after treatment failed Wednesday, provincial authorities said Thursday.

His death takes the number of dead in China from A/H1N1 to 21 for 2011.    The man, 55, was first found with the virus on January 13. Eight days later, he was admitted to a local hospital in Shenzhen City where he died, according to a statement from Guangdong's public health department.

A/H1N1 has re-emerged in China over the past two months. The country has reported 129 severe cases of A/H1N1 since the end of 2010, after 18 straight weeks without any severe cases.

Another patient "in critical condition" is being treated with six others with severe symptoms in Guangdong, the statement said.

A weekly report by the Chinese National Influenza Center showed that A/H1N1 had replaced influenza A (H3N2) as the predominant flu strain in 2011.

Shu Yuelong, director of the center said China had entered the peak influenza season and more acute cases of A/H1N1 would occur. "But the pandemic would not be as severe as that in 2009."

The A/H1N1 flu outbreak peaked in terms of severity in 2009. The Chinese mainland reported its first case in May of that year. More than 120,000 A/H1N1 flu cases were recorded in 2009, with 648 of them leading to death.

Shu said current monitoring results showed that both the percentage of flu-like cases in outpatient and emergency visits and confirmed cases of influenza were lower than the level in the same period last year.

He said that vaccination against A/H1N1 had been effective.