(Agencies)
Updated: 2004-02-11 11:40

It could take two years to control bird flu among poultry, and people will remain at a low-level risk of catching the deadly disease, the World Health Organization (WHO) said Tuesday.

Mike Ryan, WHO's global response coordinator for avian flu, also said in an interview the U.N. agency was sending fresh teams to China and Laos, bringing to about 50 the number of experts deployed in the field.

The H5N1 bird flu virus has broken out in eight Asian countries, devastated poultry flocks and killed at least 14 people in Vietnam and five in Thailand.

The human victims are all believed to have caught the disease from contact with sick chickens but there are fears the bird flu virus could combine with a human flu virus and mutate into a new deadly disease that could be passed between people.

"We are probably looking at six months to two years before some of these outbreaks can be brought under total control in the poultry population," Ryan said.

"So the reality of that is there is going to be chronic, low-level exposure of human populations to the virus," he said.

Each such exposure had the potential to generate a modified version of the new human form of the illness.

Ryan, who heads WHO's Global Outbreak Alert and Response Network, which tracks epidemics and coordinates international investigations, said the world must keep up its guard.

It would be a challenge to sustain activities in terms of financing and in getting partners -- which include agencies such as the U.S. Centers for Disease Control -- to provide experts to help national health ministries in their fight.

TEST MIX-UP

WHO also said Tuesday it had jumped the gun in declaring tests on victims had shown no genetic evidence that bird flu could be passed from person to person.

Its announcement last Friday had been greeted with huge relief. But the WHO said that there had been a mix-up in the testing of two Vietnamese sisters who died after catching it, and that results initially given for one of them had turned out to be from another patient instead.

The results of genetic sequencing of the virus from the second sister is due this week, according to a statement.

Ryan said the importance of the results may be overstated.

"The fact is that this was clearly a dead-end event. We haven't seen any disease beyond that cluster. If this truly had been transmitted in any significant, meaningful way to public health, we would know all about it. That is probably the more important fact of the matter," he said.

However, clusters of the disease among humans must be thoroughly investigated -- even though such studies over a long period of time were exhausting for the WHO and its partners.