Bird flu may be less deadly than supposed, based on blood serum evidence of many past mild infections in Asia, according to a study released by the journal Science. In the study, led by microbiologist Taia Wang of the Mount Sinai School of Medicine in New York, the biomedical team compiled evidence of antibodies to the virus collected from 12,677 Asians, Africans, and Europeans in 27 studies dating from 1997 to 2009.  The team estimates that about 1.2 percent of those individuals had survived wild bird flu cases.  That corresponds to “millions of people who have been infected worldwide,” the study said.

Bird flu travels from poultry to people, but not from person to person.  The World Health Organization (WHO), based on a review of about 600 cases, estimated that the virus strain kills more than half its victims.  But, the new study suggests that the death rate looks to be overstated.  “WHO does not account for a majority of infections, but rather the select few hospitalized cases that are more likely to be severe,” the study said.  This could mean an under count of patients who suffer only minor bird flu illness, inflating the death rate.

“The bottom line is that it looks like a whole lot of people become infected and don’t die,” says Columbia University virologist Vincent Racaniello, who was not part of the study.  “How much lower the death rate is, we don’t know.”  By comparison, the death rate for the 1918 flu that killed more than 675,000 people nationwide, often young and otherwise healthy individuals, was about 0.5 percent.  The seasonal flu has a death rate of about 0.1 percent, often among the elderly.