Bird flu fears widen
http://www.current-biology.com/content/article/fulltext?uid=PIIS0960982206011973
Nigel Williams
The Tower of London's famous ravens are now, for the first time in 400 years, locked up inside the building. The move marks growing European fears about the prospect of the H5N1 bird flu, which has caused more than 90 human deaths, mostly in Asia, and is greatly feared as a potential source of the next human global flu pandemic.
Europe is battening down the hatches on its poultry population in the face of the H5N1 infection of wild birds now recorded across the region. But news that birds in Africa have been confirmed with bird flu has added an extra dimension to the crisis.
Bird flu in Africa has raised fears for experts that containing it will be a major problem on a continent where backyard chickens are the norm, health infrastructure is weak and many governments have little in the way of funding or plans to deal with an avian flu outbreak.
In northern Nigeria, where bird flu began killing chickens last month, cheap chicken has flooded local markets. Poultry farm workers, faced with thousands of dead birds, are working without protective gear to throw them on open fires. And farmers, not yet certain what government compensation they will receive, remain reluctant to report dying birds.
“If the situation in Nigeria gets out of control, it will have a devastating impact on the poultry population of the region. It will seriously damage the livelihoods of millions of people and will increase the exposure of humans to the virus,” warned Samuel Jutzi, director of the United Nations' Food and Agriculture Organization, which has sent experts to Nigeria to try to contain the outbreak there. Nigeria's new cases “prove that no country is risk-free and that we are facing a serious international crisis,” he said.
International experts quickly confirmed that the H5N1 strain of bird flu has been identified on at least four poultry farms in three states of northern and central Nigeria. What is unclear is whether the deadly virus — also recently discovered in Germany, Austria, Greece, Iran, Italy and Slovenia — reached the west African nation through migrating wild birds, in poultry imports, or by some other method.
What worries international flu experts is that Africa could prove an ideal place for the disease, which is now deadly to birds but only rarely passed to humans, to mutate into a form capable of infecting and killing large numbers of people.
So far, the disease has killed just over 90 people, primarily in Asia, but earlier flu pandemics that made the jump to human beings — like the Spanish flu of 1918–19 — have killed tens of millions worldwide.
Across Africa, as in Asia, “there's very close interaction between farmers and their birds,” many of which run free in and around homes, said Duncan Mwqngi, a researcher with the International Livestock Research Institute in Kenya. “African governments now have a huge task of trying to educate the public about the dangers. Without that, a lot of people will be exposed to the disease.”
Africa has in recent months rushed to prepare to combat bird flu. South Africa and Morocco have been testing migratory birds on their lakes and wetlands for the disease, and Malawi recently determined that a die-off of wild birds there was due to bad weather rather than avian flu. More than 40 of the continent's governments sent representatives to a WHO meeting on the problem in Central Africa.
But preparedness remains the exception on the continent. As of the end of last November, only a third of the continent's countries had begun any planning process for dealing with avian flu, according to the WHO's regional Africa office.
The threat to Europe from birds migrating this spring is adding to the pressure to protect the public and poultry flocks with a vaccination programme. There are growing calls on European governments to allow vaccination of poultry and valuable zoo birds against bird flu as more countries move chickens, geese and ducks indoors.
Both Italy and the Netherlands, which have experienced bird flu outbreaks in their poultry flocks in recent years, are keen to implement vaccination measures to prevent this happening again, particularly with this virulent strain of bird flu.
But in Britain, scientists and vets are divided on the issue, while British zookeepers want inoculation but say supplies are unreachable because ministers have not applied to vaccinate birds under EU rules.
There was also uncertainty as to whether the British government had sufficient supplies for more than a limited vaccination programme. It has not ordered doses ahead of an outbreak because of doubts about practicality. Farmers, vets and zoo specialists met officials from the environment departments and agreed not to move birds indoors and hold back on vaccination.
Organic and free-range poultry keepers, many of them small-scale producers, fear their businesses could collapse if the government implements a contingency plan to house all poultry.
Up to last month, no birds have been tested positive for the H5N1 virus in Britain. Some vaccination is under way in France, the Netherlands, and Belgium, and Italy also favours its use.
Poultry sales are plummeting in countries where bird flu has struck wild birds in recent weeks. Sales in Italy have plunged 70 per cent and in France by 15–20 per cent. In Germany troops in protective gear have been helping to decontaminate vehicles.
Vets are uncertain over vaccination. Freda Scott-Park, president of the British Veterinary Association, said: “No one is closing the door on vaccination but it is fraught with difficulties. We do not know if there is enough vaccine available and the logistics would be very difficult.”
Intervet International, which is supplying more than 30 million doses of a generic H5 avian flu vaccine to France, said the British government and zoo owners had inquired about availability, but it had not yet received a fixed order. It might take weeks or longer to fulfil a contract because it could not guarantee supplies if demand continued to grow.
The British government's agriculture department said early detection, slaughter of infected birds, and movement controls provided the most effective method of eradicating bird flu as swiftly as possible. It added: “Vaccination offers potential benefits but currently available vaccines are too limited to provide a general solution… we, of course, keep our policy under review as the vaccine manufacturers continue to develop their products.”
And a new study of the influenza virus in birds in south-east Asia raises a deeper problem of the viruses entrenched there. A team led by H. Chen at the Shantou University Medical College and Hong Kong University in China, together with colleagues in China, Vietnam, Malaysia, Indonesia and the US, report in the Proceedings of the National Academy of Sciences in the US, (published online), a study of the virus in poultry in the region.
They report genetically and antigenically distinct sublineages of H5N1 virus in poultry in different areas of south-east Asia. They believe this indicates the long-term endemicity of the virus and also, worryingly, they find isolates of H5N1 from apparently healthy migratory birds in southern China.
“Our data show that the H5N1 influenza virus has continued to spread from its established source in southern China to other regions through transport of poultry and bird migration,” the authors report.
“The identification of regionally distinct sublineages contributes to the understanding of the mechanism for the perpetuation and spread of H5N1, providing information that is directly relevant to the control of the source of infection in poultry.”
But the bad news is that they believe wider surveillance of the flu strain will be necessary and variants of H5N1 need to be considered. No one, it appears, is out of the spotlight.
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