Bird Flu Waning in Southeast Asia

Ongoing concerns about an avian flu pandemic among humans are being tempered by news that the disease seems to be virtually eradicated in parts of Southeast Asia where it first appeared.

"In Thailand and Vietnam, we've had the most fabulous success stories," said Dr David Nabarro, chief pandemic flu coordinator for the United Nations, according to a report in The New York Times (NYT).

In Vietnam, where almost half of the known human cases of A(H5N1) influenza occurred, has had no outbreak among humans or poultry this year. In Thailand, which until recently had the second highest rate of the disease (Indonesia is now second), no case of human A(H5N1) virus has been reported in five months (or in poultry in six months). China also reports encouraging news, although, according to the NYT, the reports are "harder to interpret."

Bird migration has proven to post no apparent risk, as birds migrating north from Africa have not brought the virus into Europe.

A Continuing Epidemic

Despite the good news from Southeast Asia, the A(H5N1) virus continues to move rapidly across continents. It is still present in Myanmar, Indonesia and other nearby countries, according to the NYT report, and there is a risk it could reappear in any area through illegal trade in chicks, fighting cocks or pets, or in migrating birds.

On a more positive note, the decrease in incidence of the virus in Southeast Asia offers hope that aggressive measures such as inoculating healthy poultry, killing infected birds and educating farmers is a workable option, even in poor countries.

Differing Strategies

Vietnam and Thailand implemented significantly different methods to fight the virus: Vietnam began vaccinating all its 220 million chickens last summer, but Instead, Thailand instead culled wide areas around infected flocks, paid farmers generously and deputized someone in each village to report sick birds.

In Vietnam, valuable fighting cocks are vaccinated, and they even receive passports with their vaccination records, according to Dr Nabarro.

Thailand chose not to vaccinate because of its large poultry export industry - other countries may have banned its birds indefinitely, as vaccines can mask the A(H5N1) virus, instead of killing it. In February, Thailand reported that tests of 57,000 birds were negative.

Vietnam and Thailand also provided antiviral drug Tamiflu to even the smallest regional hospitals, instructing that all flu patients should receive it, even before laboratory diagnoses could be made, according to Dr Klaus Stöhr, a flu specialist at the World Health Organization.

Bird Flu in China

China has reported low numbers of human cases of the virus: 8 last year and 10 this year. However, officials often greet China's official public health reports with skepticism, partly because of the delay in reporting the SARS outbreak there, and because China did not officially report bird flu cases "for years", according to the NYT, although scientists believe the virus incubated there from 1997 (after the first appearance in humans in Hong Kong) until 2003.

Chinese cases of bird flu among poultry are dropping, which in turn reduces the risk of human transmission and the possibility of a mutant pandemic strain developing. The World Health Organization says that China reported outbreaks in 16 provinces in 2004 and 12 in 2005, although one large outbreak in November prompted culling of 2.5 million birds.

Following this report, the Agriculture Ministry announced its intention to vaccinate every domestic bird in China, which raises and consumes 14 billion chickens, geese and ducks annually. Dr Stöhr, who is in charge of WHO flu vaccine efforts, said that Chinese agriculture officials told him that China was now annually producing 46 billion doses of poultry vaccine, and supplying vaccines to Vietnam.

The most recent reports from China describe smaller outbreaks. "We are hopeful that China has turned the corner," Dr Nabarro reportedly said.

Most health specialists believe that the chance of infected birds landing in the United States is low, according to the NYT report. However, the risk of the virus returning to areas where it is on the wane is ever-present, according to Dr Nabarro.

"Tomorrow, the whole thing could change again," he reportedly said. "We need to be on the alert at all times."

Source: Flu Wanes in Asian Nations It First Hit Hard, The New York Times, May 14, 2006.

Posted: May 2006


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