Our response has to be proportionate and happily, so far, it has been. The virus that killed one British swan is not easily transmitted to humans and not at all communicable between them. Sensible measures are already in place to contain the disease, measures that were planned and well-rehearsed.
As we report today, David Nabarro, the United Nation's global co-ordinator on bird flu, says that Britain has among the best plans in the world for dealing with the disease in birds and its possible spread to humans. Unfashionable though it is to say it, we have good grounds for trusting the government to get this right. Compare our situation with that in the United States, where there are insufficient antiviral drugs for even one-100th of the population. We can supply one quarter, covering those most at risk. For months now, the NHS and police have been testing plans to deal with a major public-health crisis.
If a pandemic of lethal flu were to hit Britain, it would have terrible social and economic consequences, but the vast majority of us would live through it unscathed. Tragically, that cannot be said of most other populations in the world. The effects in sub-Saharan Africa, for example, where populations are already weakened by HIV and malaria, would be catastrophic. Though the threat of bird flu has prompted investment in vaccine technologies, predicting future mutations of the virus is difficult.
Containing the spread of the disease among birds is the best measure currently available. It is now endemic in poultry and wildfowl across south east Asia and parts of eastern Europe. The biggest danger lies in countries where birds and people live in close proximity. The scientific consensus is that here doctors would have only a few weeks to identify a mutated form of the disease and to isolate infected people before it began to spread globally.
This makes it essential that countries where flocks are heavily infected do everything possible to enforce biosecurity - the physical separation of species. This tactic has already worked in Vietnam and Thailand and is working, albeit patchily, in Turkey. But others lag behind. Indonesia, for example, suffers unnecessary human casualties because its poultry farmers resist changing the conditions in which they keep birds and are reluctant to cull them at the first sign of infection.
China's Communist party, by keeping the country closed to international intervention, is also an obstacle to protecting Asia and the rest of the world. The World Health Organisation has stockpiles of drugs to target specific outbreaks, but there is not yet a coherent multinational strategy that would pool resources, including people, to contain the spread of the disease in the poorest parts of the world.
Meanwhile, it is up to individual governments. Only they can explain the risks to people, set up surveillance systems to pick up diseased birds and compensate farmers properly - and in ways that do not encourage bogus culling for financial gain.
The threat to Britain does not come from a hapless swan. It comes from those countries that fail to co-operate to halt the disease before it spreads outside their own borders. But, equally, it comes from a failure by those governments that are well prepared to share their expertise and resources with poorer countries that are not.