The World Health Organization has confirmed a fifth person has died after becoming infected with the bird flu in Vietnam. Meanwhile, a Hong Kong scientist says the latest bird flu virus appears more adept at infecting children than its predecessors.

The World Health Organization in Vietnam confirmed Monday that an eight-year-old girl died of bird flu three days after being admitted to a Vietnam hospital on January 15.

She was the forth child confirmed with the illness - one adult has also died - but all seem to have contracted the virus from infected chickens.

Bob Dietz, a WHO spokesman in Vietnam said several more suspected victims are being tested. "We're looking at new cases that are coming in, but we're still not seeing a flood," he said.

The disease has been spreading through poultry farms across Vietnam, South Korea, Japan and Taiwan for several weeks but only Vietnam has reported human cases.

The first known human cases occurred in Hong Kong back in 1997. Six of the 18 people infect died of the disease.

One expert in the disease says children appear to be more susceptible to the latest bird flu, or H5N1 virus, than they did in the last outbreak.

"In the bird flu in Hong Kong in 1997, children had milder disease compared to adults," said Dr. Malik Peiris, a researcher at Hong Kong University's microbiology department. "Surprisingly, this particular virus that's causing problems in Vietnam is behaving quite differently."

Dr. Peiris said generally it is human influenza viruses that tend to be more serious in the very young.

As Vietnam tries to bring the bird flu outbreak under control by culling millions of chickens, Hong Kong has stepped up precautions against fresh SARS outbreaks.

Since December, China has confirmed three isolated Severe Acute Respiratory Syndrome (SARS) cases. Health officials in the region fear a repeat of the first outbreak, which infected 8,000 people after emerging from southern China in late 2002.

Hong Kong's health department says that since December, authorities have stopped at least 133 people entering Hong Kong with fever, none of whom were suspected of having SARS.

A department spokeswoman says she expects more will be stopped as people travel to and from Hong Kong during the approaching Lunar New Year holiday.