Hanoi, Feb. 8 (Reuters): Up to 70 per cent 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 per cent, so we are quite shocked by this,” David Hui, specialist in respiratory medicine at the Chinese University of Hong Kong, told Reuters Television. “Last time (in 1997), the mortality rate was 30 per cent.” 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 the World Health Organisation efforts to contain the bird flu outbreak.

Resource- and expertise-strapped Hanoi has already gathered a large team of overseas experts to help it halt the virus, which has struck virtually all of its 64 provinces and major cities. Vietnam has ordered a nationwide ban on the transport of poultry and Hanoi yesterday ordered a cull of all fowl in the city.

Hong Kong saw a similar H5N1 strain of bird flu in 1997, which killed six people. A cull of the territory’s entire 1.5 million poultry population in three days is credited with stopping the virus in its tracks. This time, bird flu has been reported in 11 countries so far — the deadly H5N1 strain as well as milder types like H7 that was detected this weekend in the US.

Japan bans US chicken

Japan has banned chicken imports from the US following the discovery of bird flu in Delaware, the latest concern in a country heavily dependent on imports for its food needs. The agriculture ministry said today it was trying to confirm the nature of the illness in Delaware .