China's Center for Disease Control and Prevention (CDC) has asked the country's monitoring hospitals to report influenza cases on a weekly basis in the six months from October as the flu season begins.

Hospitals should input all flu cases to the state influenza monitoring information network every Monday, according to a notice issued by the center.

The network consists of 198 hospitals and 63 laboratories. The notice said hospitals should collected virus samples and deliver them to appointed laboratories on a regular basis.

"Our focus is on the number of flu cases, the species of virus strains and the antigenicity, gene features and drug resistance of the virus strains," Yu Hongjie, a researcher with the Chinese CDC, said.

Influenza is an infectious disease in birds and mammals. In serious cases, it can lead to pneumonia, which can be fatal, particularly in young children and the elderly.

Three major international pandemic flu outbreaks occurred last century: from 1918 to 1919; 1957 to 1958; and 1968 to 1969. They caused huge economic losses and killed millions of people.

A deadly avian strain named H5N1 has posed the greatest risk for a new flu pandemic since it first killed humans in Asia in the 1990s. Fortunately, this virus has not mutated to a form that spreads easily between people.

Yu said the virus strains most widely spread around globe since 1997 were influenza virus A (H1N1), virus A (H3N2) and virus B.

The researcher said flu epidemics in China in recent years remained generally stable and the most common virus strain in China last spring was influenza virus B.

(Xinhua News Agency October 7, 2008)