Bird flu resurfaces in Asia, threatens human health

ROME, Italy, July 12, 2004 (ENS): New outbreaks of the avian influenza virus H5N1 in China, Thailand and Vietnam confirm that the virus is still spreading in the region, the United Nations agency responsible for food and agriculture said Friday. This viral strain caused the deaths of more than 100 million chickens and ducks in Asian countries earlier this year. Some birds died from the flu, but the vast majority were culled in an attempt to control the virus.

"The new cases do not come as a surprise," said Joseph Domenech, chief of the UN Food and Agriculture Organization's Animal Health Service.

China reported a new outbreak of bird flu last Tuesday. It was China's first report of the H5N1 virus since the government declared it had stamped out the disease nearly four months ago. Tests at a farm in the southeastern province of Anhui have confirmed that chickens died of bird flu, the government said on state-run television.

In Thailand, authorities said they suspect a new outbreak of bird flu at a farm in the central province of Ayutthaya. Thousands of chickens at the farm have died.

Bird flu has also been confirmed on farms in Vietnam in recent days, and about 4,700 chickens have died.

"After the major outbreaks of a few months ago, affected countries succeeded in bringing the disease under control. But the new outbreaks clearly demonstrate that the virus continues to circulate in parts of the region and new cases might flare up in future, posing a continuing threat to human health," Domenech said.

"In designing their control strategies governments need to acknowledge that the virus will continue to circulate and that different flu viruses could also be introduced. Eradication of the avian flu virus should be considered, at best, as a long-term task," he warned.

The World Health Organization (WHO) said Thursday that these outbreaks could either be new outbreaks of the highly pathogenic avian influenza A H5N1 virus, or, a continuation of the outbreaks first reported earlier this year.

"These events, in addition to two new research reports about the virus becoming increasingly pathogenic and becoming more widespread in birds in the region, fuel the World Health Organization's concern about the threat the virus poses to human health," the agency said.

Several countries in Asia have documented this virus crossing the species barrier - moving from infected chickens or ducks directly into humans - three times since 1997 with severe, and sometimes fatal, outcomes. "The virus has the potential to acquire the ability to spread easily from human to human, and, thus, trigger a global influenza pandemic," WHO said.

The two research resports that worry WHO officials were both published this month. First, members of China's Ministry of Agriculture, and colleagues, reported, in a paper published in the "Proceedings of the National Academy of Sciences," that the virus appears to be widespread in domestic ducks in southern China. The scientists found that the virus is causing increasingly severe disease, but these tests were done in mice and "may not have a direct implication for humans," WHO said.

Last week, the journal "Nature" published a report which indicates domestic and wild birds in the region may have contributed to the increasing spread of the virus, and, suggests that the virus is gaining a stronger foothold in the region. These observations suggest that control of the virus may be even more difficult than thought in the spring.

K.S. Li and 21 others from universities in China, Indonesia, Thailand, Vietnam and the United States are coauthors of the "Nature" article. "Our results suggest that H5N1 viruses with pandemic potential have become endemic in the region and are not easily eradicable," they write. "These developments pose a threat to public and veterinary health in the region, and, potentially, the world, and suggest that long-term control measures are required."

It is probably unreasonable to expect that the disease can be totally excluded from the region in the near future, Domenech said. In his view, managing the risk that the viruses pose to human health and animal productivity is the challenge. "The presence of highly pathogenic strains of the virus in wild birds makes control of the disease particularly complex and difficult," he said.

It is very encouraging that governments have reacted immediately on recent outbreaks and have officially informed international organizations, the FAO said. This demonstrates that country surveillance systems are becoming operative.

But the UN agency warned that surveillance and immediate reaction to outbreaks need to be strengthened and applied in all countries of the region. "In some countries the extent of infection is still not precisely known and further investigation is urgently needed," Domenech said.

"Countries should apply surveillance and control measures nationwide and should consider the fight against bird flu as a long-term commitment. There is no easy solution to the problem," he said.

Currently, there are indications that the virus is still present at least in Cambodia, China, Indonesia, Thailand and Vietnam providing the potential for renewed epidemics as poultry production systems are re-stocked with vulnerable birds.

Pandemic preparedness activities started by WHO in the wake of the outbreaks reported earlier this year are continuing.

At the end of June, WHO hosted a meeting in Kuala Lumpur, Malaysia with experts from 13 countries and areas of the Asia-Pacific region. Participants were provided with a WHO preparedness self-assessment tool.

WHO is collaborating with scientists, and the pharmaceutical community, on a global surveillance system to monitor changes in the virus's susceptibility to known antivirals.

And vaccine development continues. Two vaccine manufacturers, both based in the United States, have produced a supply of trial vaccine which will be tested for safety and efficacy in humans.

Key elements of a successful control strategy are surveillance operative in all production systems, strengthened biosecurity of commercial enterprises and an immediate response to outbreaks including stamping-out in affected areas, plus disinfection, restriction of movements of animals and goods, and public awareness campaigns.

Copyright Environment News Service (ENS) 2004. All Rights Reserved.

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