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On sentry duty in fight against avian flu
von Tom Mitchell (Hong Kong)
Europe may be ill-prepared for a pandemic, but Hong Kong is the gold standard on containment.
A small bird dies and within hours a concerned resident has called the authorities, which quickly set up a cordon around the dead creature as if dealing with the scene of a violent crime. Soon, health workers in protective garb remove the carcass for testing at a remote lab and set about disinfecting the site.
If, or when, the bird tests positive for H5N1, the flu virus that has prompted global fears of a looming pandemic, aviaries within a 3km radius are quickly closed to the public. Anyone who has had contact with the bird is tested by health officials.
Hong Kong authorities performed the routine some 10,000 times last year on wild birds that dropped dead in the territory, as part of what is arguably the world's most advanced system for the monitoring and prevention of avian influenza.
As Europe prepares for a possible bird flu pandemic it is also learning how to react to outbreaks of H5N1 in birds. And the World Health Organisation says in that respect Hong Kong represents "the international gold standard".
"The city is all eyes. One dead bird makes people very suspicious," says Peter Cordingley, the WHO's main spokesman on bird flu in Asia.
The territory's expertise was born of bitter experience. Less than six months after the former British colony reverted to Chinese sovereignty in July 1997, it played host to the first documented human cases of H5N1. Eighteen people were infected and six died. According to the WHO, since then 271 human cases and 165 fatalities have been recorded in Asia, primarily in Vietnam and Indonesia.
"The 1997 outbreak was a watershed event," says Dr Tsang, who was at the forefront of the effort to contain it. "Until then we had very little knowledge of avian influenza. We had only dealt with seasonal flu."
No one single source, or epicentre, was identified, although contact with live poultry was the most likely trigger. At the time, 19 per cent of all chickens in Hong Kong were believed to have been infected with H5N1, and 1.5m were culled.
The Hong Kong government's handling of the event was not without its critics. One enduring image of the outbreak is that of the occasional groggy but determined hen, having survived attempts to gas it, pecking its way out of a rubbish bag.
But Dr Tsang says the government deserves credit for its management of what could have been an unprecedented epidemiological incident. He says the outbreak was contained with relatively few deaths and led to the creation of the crucial monitoring systems now in place. While H5N1 remains difficult to transmit between humans the emergence of a more easily transmittable variant and what might become a pandemic strain is still health experts' greatest fear. In a crowded city such as Hong Kong, where millions live tightly packed in tower blocks, such a virus could wreak havoc.
The 1997 outbreak also inspired a range of monitoring mechanisms for poultry suppliers in Hong Kong and China, which supplies about half the territory's chickens. In addition to regular vaccinations, testing and twice-monthly "rest days" during which Hong Kong's main poultry wholesale centre is cleared and cleansed, the system relies heavily on so-called "sentinel" chickens.
The farmyard version of a coal mine canary, sentinel chickens are deliberately not vaccinated for H5N1. A sentinel's death can signal the presence of the virus and prompt a precautionary cull. As Dr Tsang says: "Hong Kong cannot afford to have another outbreak."
Efforts to impose measures to prevent the virus's spread have not all been successful. A decade after the initial outbreak, the drive to introduce a central slaughterhouse to reduce the chance of infections from live poultry remains in the planning stages, opposed by a powerful poultry lobby and an enduring preference for freshly killed chickens.
von Tom Mitchell (Hong Kong)
Europe may be ill-prepared for a pandemic, but Hong Kong is the gold standard on containment.
A small bird dies and within hours a concerned resident has called the authorities, which quickly set up a cordon around the dead creature as if dealing with the scene of a violent crime. Soon, health workers in protective garb remove the carcass for testing at a remote lab and set about disinfecting the site.
If, or when, the bird tests positive for H5N1, the flu virus that has prompted global fears of a looming pandemic, aviaries within a 3km radius are quickly closed to the public. Anyone who has had contact with the bird is tested by health officials.
Hong Kong authorities performed the routine some 10,000 times last year on wild birds that dropped dead in the territory, as part of what is arguably the world's most advanced system for the monitoring and prevention of avian influenza.
As Europe prepares for a possible bird flu pandemic it is also learning how to react to outbreaks of H5N1 in birds. And the World Health Organisation says in that respect Hong Kong represents "the international gold standard".
"The city is all eyes. One dead bird makes people very suspicious," says Peter Cordingley, the WHO's main spokesman on bird flu in Asia.
The territory's expertise was born of bitter experience. Less than six months after the former British colony reverted to Chinese sovereignty in July 1997, it played host to the first documented human cases of H5N1. Eighteen people were infected and six died. According to the WHO, since then 271 human cases and 165 fatalities have been recorded in Asia, primarily in Vietnam and Indonesia.
"The 1997 outbreak was a watershed event," says Dr Tsang, who was at the forefront of the effort to contain it. "Until then we had very little knowledge of avian influenza. We had only dealt with seasonal flu."
No one single source, or epicentre, was identified, although contact with live poultry was the most likely trigger. At the time, 19 per cent of all chickens in Hong Kong were believed to have been infected with H5N1, and 1.5m were culled.
The Hong Kong government's handling of the event was not without its critics. One enduring image of the outbreak is that of the occasional groggy but determined hen, having survived attempts to gas it, pecking its way out of a rubbish bag.
But Dr Tsang says the government deserves credit for its management of what could have been an unprecedented epidemiological incident. He says the outbreak was contained with relatively few deaths and led to the creation of the crucial monitoring systems now in place. While H5N1 remains difficult to transmit between humans the emergence of a more easily transmittable variant and what might become a pandemic strain is still health experts' greatest fear. In a crowded city such as Hong Kong, where millions live tightly packed in tower blocks, such a virus could wreak havoc.
The 1997 outbreak also inspired a range of monitoring mechanisms for poultry suppliers in Hong Kong and China, which supplies about half the territory's chickens. In addition to regular vaccinations, testing and twice-monthly "rest days" during which Hong Kong's main poultry wholesale centre is cleared and cleansed, the system relies heavily on so-called "sentinel" chickens.
The farmyard version of a coal mine canary, sentinel chickens are deliberately not vaccinated for H5N1. A sentinel's death can signal the presence of the virus and prompt a precautionary cull. As Dr Tsang says: "Hong Kong cannot afford to have another outbreak."
Efforts to impose measures to prevent the virus's spread have not all been successful. A decade after the initial outbreak, the drive to introduce a central slaughterhouse to reduce the chance of infections from live poultry remains in the planning stages, opposed by a powerful poultry lobby and an enduring preference for freshly killed chickens.