The specter of a global influenza pandemic has loomed a little larger in recent weeks with revelations that Chinese researchers found the deadly H5N1 virus strain last year in pigs, a crucial link in the mutation of the disease to a form that can infect humans.
Chinese officials have confirmed that the virus—which has killed 27 people in Asia so far this year—was found in pigs in the southeastern province of Fujian in 2003, official media reported. But the agricultural ministry has denied a report that pigs were found to be infected in "another place" this year.
The initial revelation was made by Chen Hualan, director of the China National Avian Influenza Reference Laboratory. It came as a surprise to World Health Organization (WHO) representatives present at the seminar, who heard about it for the first time.
Chen called the finding "a rather dangerous signal in terms of public health.”
Once influenza mutates to infect pigs, it is far closer to a form that can infect humans. Many influenza strains are born where poultry, pigs, and people live in close contact.
Chinese officials claim that no human infections have been found so far, but they had also previously claimed that no pig infections had been found, either.
Chinese public health procedures have come under intense scrutiny and suspicion since an official attempt to cover up the extent of the SARS epidemic of 2003 was exposed by a military doctor in Beijing.
The doctor, who has also called for a re-appraisal of the 1989 military crackdown on democracy protesters, was detained for several months at an undisclosed location. Local editors at a newspaper in the southern Chinese city of Guangdong that broke news about the deadly SARS virus have been harassed and detained.
WHO said the discovery of the virus in pigs had taken the world closer to a human flu pandemic.
Asked about the threat of a global epidemic if pigs had been infected, WHO regional director for the Western Pacific Shigeru Omi said: "Of course it's a little bit closer but how close we don't know. This is one factor we have to monitor very closely."
"So far cooperation with the Chinese government has been excellent and collaboration with the Chinese authorities has been transparent and open. I hope the same spirit will continue," he told a news conference in Penang, Malaysia.
The WHO needed to study how widespread the virus was among pigs, he said. "At this point, there is no need for the global community to panic but it doesn't mean we can relax. We need to remain vigilant."
But he warned of a "long battle" that could last several years before bird flu is wiped out in Asia, mostly because of poor management and surveillance of animal husbandry.
Thailand, Vietnam, China, and Malaysia have reported new cases of bird flu in poultry following the outbreak earlier this year that led to the culling of millions of birds, devastating poultry industries.