Up to 70 percent of people who have caught bird flu in the latest Asian outbreak have died from the
virus, around twice the level in the 1997 outbreak in Hong Kong, a doctor from the territory said today.
"The data suggests it is in the range of 60 to 70 percent, so we are quite shocked by this," David Hui, specialist in respiratory medicine at the Chinese University of Hong Kong, told Reuters. "Last time (in 1997), the mortality rate was 30 percent."
Eighteen people have died in the latest outbreak, 13 in Vietnam and five in Thailand.
Hui said there was little evidence that the virus was being spread by anything other than contact with sick poultry, but that it was unclear why the H5N1 strain was this time more lethal or why only two countries have reported human deaths.
"This is a puzzle, in fact this is one of the purposes of the trip, we are trying to find out is the virus changing in structure? Is it becoming more virulent? Is the clinical spectrum different from 1997?" he said.
Hui is one of four experts from Hong Kong who arrived in Vietnam today to join World Health Organisation efforts to contain the bird flu outbreak.