BEIJING // Fears over the spread of bird flu have been raised after Hong Kong confirmed its first case of the deadly illness in seven years.
Officials have revealed a 59-year-old woman, who had recently visited mainland China, had developed the often fatal condition.
While the victim remained in a serious condition quarantined in hospital, experts yesterday said concerns remained the H5N1 virus could end up spreading person-to-person, potentially leading to a pandemic.
In the wake of this week's case, officials in Hong Kong raised the alert for bird flu to "serious", indicating a threat of catching the disease exists.
Despite the suspected source of the outbreak, Hong Kong's food and health secretary, York Chow, insisted poultry imports from mainland China remained safe.
"Since there is one case, we have to be very careful as it might actually point out its source of infection, which might give rise to another case," he told reporters.
Mr Chow said it was likely the woman had picked up the virus while on the mainland, though this had yet to be confirmed.
According to reports, the victim visited Shanghai, Nanjing and Hangzhou while in mainland China with her husband and daughter from October 23 to November 1. A day after returning, she began to show flu-like symptoms and these intensified until she was admitted to hospital on Sunday.
Mr Chow yesterday told media there was no evidence that eight close contacts of the woman had symptoms of the disease, lessening concerns any human-to-human transmission had taken place. The woman's husband initially showed flu-like symptoms, but has since recovered.
If any close contacts of the woman were confirmed as having contracted the H5N1 virus, it would become "a very serious problem", said Paul Kay Sheung Chan, a professor of virology at the Chinese University of Hong Kong.
"For health officials responsible for preparing plans for a pandemic, they should take this seriously," he said.
"Although the chance may not be there, this is a very lethal virus."
Prof Chan said officials would need to consider measures such as mass vaccinations in the event of any human-to-human transmission being confirmed.
Although the virus that causes bird flu has yet to mutate into a form that can easily be spread through human contact, Prof Chan said the risk remains this could happen.
"It is difficult to predict. Sometimes it takes 10 years, sometimes it never happens," he said. "But I would say the chance is there. No one knows how great the chance is."
In the wake of the Hong Kong case, Taiwan yesterday said it would check the temperatures of incoming travellers. Any arriving from Hong Kong, Macau or the mainland with fever-like symptoms would be hospitalised, according to reports from the island.
The first major outbreak of bird flu in humans took place in Hong Kong in 1997. Then, prompt action in culling all poultry in the territory within three days is believed to have helped limit the final death toll to six.
The Chinese authorities, Prof Chan said, were now likely to be attempting to identify the source of the outbreak, and looking to take action there to limit the spread of the virus.
Globally, there have been about 500 confirmed cases of bird flu in humans since 2003, around 60 per cent of which have proved fatal.
The most dramatic predictions, made five years ago by a United Nations official, suggested a global bird flu pandemic could kill 150 million people, although the World Health Organisation at the time gave a much lower estimate of up to 7.4 million deaths.
For deaths to take place on a large scale, the virus would have to spread easily person-to-person, something that has happened only rarely. This situation could change either through gradual mutation of the virus, or if the virus's genetic material were mixed with that of another virus already transmissible human-to-human.