China said Thursday that no other cases of bird flu have been detected in Beijing and neighboring provinces after a woman died from the avian influenza in the capital.
The Agricultural Ministry said in a notice on its Web site that authorities had investigated poultry in Beijing, the port city of Tianjin and neighboring Hebei province, but no other cases have been found.
"Bird flu epidemic was not found in any of these three provinces and cities," it said.
Inspectors have stepped up checks of poultry markets and slaughterhouses and have banned live poultry from entering the capital after the death.
Medical professionals are also visiting families in all districts in Beijing to look out for bird flu symptoms, the China Daily newspaper said.
The World Health Organization said the case did not appear to signal a new public health threat.
China raises more poultry than any other country, many on small farms. The Agricultural Ministry said it will step up checks before the traditional Spring Festival holiday, or Chinese New Year, when hundreds of millions of people return home to their families and rural farms.
21st death
China's Health Ministry said tests confirmed that Huang Yanqing, 19, had contracted the H5N1 bird flu virus. She died Monday in a Beijing hospital.
It was the first such death in the country in almost a year, and the 21st to date in China.
The virus is generally more active during the cooler months between October and March, although the new Chinese case points to holes in surveillance of the virus in poultry.
Experts also say that many species of ducks are natural reservoirs of the virus and unlike chickens, they show no signs of disease.
China's Agriculture Ministry said it would step up an inoculation campaign and surveillance for the disease.
"The ministry has many times demanded that every part of the country must maintain a high state of alert to prevent the spread of bird flu and other animal viruses," it said.
Mutation feared
The WHO said Huang's case was similar to others reported worldwide in that it does not appear to involve human-to-human transmission.
Official Xinhua News Agency said the woman had cleaned the insides of several ducks.
Workers disinfected the market in neighboring Hebei province where the woman bought nine ducks, Xinhua said. The market's five poultry shops have been closed.
Officials worry the virus could mutate into a much-feared form that could spread easily among people. But, for now, it remains hard for people to catch, with most human cases linked to contact with infected birds.
According to the latest WHO tally, bird flu has killed 248 people worldwide since 2003, including 21 in China.
The H5N1 bird flu virus continues to devastate poultry stocks around the world. China has vowed to aggressively fight the virus.
Not a public health threat, says WHO
Tests on 15 people who worked in the poultry market were negative. Over 100 people had also been in close contact with the patient, and one nurse who treated her had come down with a fever but had now recovered, the official Xinhua agency said.
"We are concerned by any case of human H5N1 infection, however, this single case, which appears to have occurred during the slaughtering and preparation of poultry, does not change our risk assessment," the WHO said in a statement.
"WHO expects the ministry will continue to keep it updated on this case, and is prepared to offer technical assistance if requested," it added, referring to the Health Ministry.
Chinese Health Ministry spokesman Mao Qunan was quoted in state media as saying the government would step up monitoring.
"This year we must, on the basis of what we have done in the past, increase monitoring for the transmission of the highly pathogenic bird flu virus in humans," Mao said.
No signs of disease in birds
Lo Wing-lok, an infectious disease expert in Hong Kong, said the case highlighted the danger of ducks in the spread of H5N1.
"The nine ducks the woman purchased were probably carrying the virus and she was exposed. Duck innards have high concentration of the virus and cleaning nine of them is so risky," Lo told Reuters.
Paul Chan, microbiologist at the Chinese University in Hong Kong, said it was worrying this case was not accompanied by the detection of the virus in poultry nearby.
"The source of this infection seems to be poultry or the market (where the girl bought the ducks). If that is true, we need to know why we missed the outbreak of the virus in poultry or in the market," Chan said.
"If there was an outbreak in the market, there should have been large numbers of poultry (chicken) deaths. If people in the markets and the government can't recognize this, then we have a serious problem on our hands," he added.
The H5N1 strain remains largely a disease among birds but experts fear it could change into a form that is easily transmitted among people and kill millions of people worldwide.
With the world's biggest poultry population and hundreds of millions of farmers raising birds in their backyards, China is seen as crucial in the global fight against bird flu.
Since the H5N1 virus resurfaced in Asia in 2003, it has infected 391 people, killing 247 of them, according to WHO figures released in mid-December.
Vietnam's agriculture ministry has confirmed an outbreak of bird flu among poultry in the northern province of Thanh Hoa, where a girl was hospitalized with the deadly disease last week.
Thanh Hoa is the second province in two weeks to report an outbreak of the bird-borne illness among poultry, the other being Thai Nguyen, directly north of the capital.
The Associated Press and Reuters contributed to this report.
