Using new methodology, the Centers for Disease Control and Prevention has revised its estimate of the total number of deaths caused by swine flu. The new figures will result in a tripling of the number deaths from H1N1overnight

While the official estimates have not yet been released, it appears that the tally of deaths from the novel form of influenza will rise to around 4,000, up from 1,200, as first reported Wednesday by The New York Times

The changes reflect new surveillance methods thought to be more accurate but also show that figuring out the death toll from influenza is not a precise science.

"We don't really know how many cases of H1N1 there have been, truly," said Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York.

The problem is the difficulty of testing every patient to confirm a diagnosis, which is outweighed by the benefits of immediately treating patients for flulike symptoms.

"Seasonal flu numbers are very soft, based on excess deaths more than diagnoses," explained John Barry, author of "The Great Influenza." "Many, if not most, of the deaths attributed to influenza in seasonal flu are quite indirect."

"Each case of influenza is not reported either with seasonal flu or in a pandemic [like H1N1] and therefore the subsequent deaths are not always immediately traceable to a specific cause of death," said Dr. Frank James, a health officer in San Juan County, Wash., and a clinical associate professor at the University of Washington.

http://abcnews.go.com/Health/SwineFluNews/h1n1-deaths-triple-overni...