HONG KONG FLU VIRUS HAS OFFICIALS BAFFLED.

Byline: Edward A. Gargan The New York Times

Chow Hoi, his T-shirt splattered with blood, shuffled across the puddled cement floor in blue rubber slippers, plunged his hand into a wooden cage squawking with chickens and yanked out a dead bird, which he flipped onto the floor. Then another. And another.

Around him, dead chickens littered the cement where a couple of dogs snored indifferently. Black plastic bags filled with dead chickens were piled by the open-air entrance to the sour-smelling Tai Fong Sing Lan chicken wholesaler.

``I've never seen anything like this,'' the 62-year-old chicken worker said, plopping onto a steel cage of clamoring chickens. ``A thousand chickens died this morning. It's uncontrollable. There's nothing anyone can do.''

What can be done is precisely the question that is ever more urgently occupying Hong Kong authorities charged with stopping the spread of an influenza virus that ran through Hong Kong's chickens and those brought in from elsewhere in China, and has infected at least nine people.

On Tuesday, health authorities released detailed case histories of seven victims of the virus, two of whom died. They also announced that they had found two more, who were linked for the first time to another victim of the virus. That posed once again the crucial public health question: Can the flu be spread from human to human just as it seems to have been spread from chickens to humans?

The health authorities were careful not to draw quick conclusions.

``The transmission of the virus both from bird to human and human to human are possible,'' said Dr. Margaret Chan, Hong Kong's director of health. ``We have stressed that given the current evidence, there is stronger evidence to prove avian-to-human transmission, and we have never ruled out human-to-human transmission.''

At the same time, Chan - as well as other Hong Kong health authorities and Dr. Keiji Fukuda, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta - emphasized that the virus, called H5N1, that is sweeping through the chicken population has not reached epidemic levels in Hong Kong.

``I don't think we have an epidemic,'' Chan said. ``If we had an epidemic, we would have hundreds and thousands of cases.''

But Fukuda warned: ``Whenever a new virus like this appears and causes a small number of cases like this, it creates tremendous concern among scientists. Influenza viruses are almost unique in their ability to spread rapidly around the world.''

There have been three influenza pandemics this century. In 1957, the influenza pandemic killed between 90,000 and 100,000 in the United States alone.

Although the first death from this new virus, that of a 3-year-old child, occurred in May, only Tuesday did Hong Kong's health, hospital and agricultural officials meet jointly to devise steps to combat the spread of the disease.

Chan said the committee ordered ``tightened control on the import of chicken, enhanced surveillance in both man and poultry, as well as improvements in environmental hygiene in markets.'' Several wholesale poultry markets have been closed for inspection and cleaning, and chickens outside Hong Kong will be required to be certified by Chinese veterinarians as free from the virus.

However, because the border with the rest of China is now increasingly porous, thousands of chickens are smuggled into Hong Kong daily, according to reports in local newspapers.

Meanwhile, detailed genetic testing of the virus found in seven victims has been done by the CDC in Atlanta. Thousands of blood tests, hundreds of interviews and throat cultures of relatives and acquaintances of flu victims have been taken in an effort to determine the precise transmission of the virus.