TECHNOLOGY has always been a double-edged sword. While intensive farming has ended hunger in much of the world, it has downsides, too. One is that crowded livestock are easy prey for infectious diseases. Witness the H5N1 bird flu that evolved in Chinese hen houses, exploded across Asia, took up residence in a few migratory ducks and has now arrived in Europe.
H5N1 is likely to persist for some time in the wild in its present form, so the world will have to learn to live with it. The question is how? First, we must prevent it rampaging through poultry. This is hard. In 2003, when a far less dangerous bird flu ran amok in the Netherlands, it took the well-organised Dutch months to get rid of it. They had to kill half their chickens. Dozens of people were infected, one of whom died.
Such an outbreak of H5N1 could be hellish. Parts of Europe 鈥� including some regions of the Netherlands 鈥� have very high densities of chickens, which shed copious quantities of flu virus. If H5N1 reaches areas like this it threatens to cause the viral equivalent of a firestorm. Most likely, more people will be infected and more will die. Every human infection gives the virus another chance to adapt so it can spread from person to person.
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Fortunately we have a technology to stop this 鈥� a vaccine. As recently as 2003 scientists rejected this, but attitudes have changed among those who fought outbreaks in Europe. It seems that knowledge has yet to reach government advisers. They still follow the textbook line that vaccinating livestock is bad because viruses can spread in vaccinated animals, and do so invisibly.
The old way to stop epidemics was to leave animals vulnerable and kill them when they fell sick. That was the UK鈥檚 strategy with foot and mouth disease in 2001, and the one nearly all Europe鈥檚 government scientists support for bird flu 鈥� except the Dutch.
True, it is likely that widespread vaccination of Chinese poultry against H5N1 allowed the virus to spread invisibly, evolving as it went. But we now have a way to spot the disease in vaccinated birds, so we can stop it spreading covertly. Italy has used the technique in birds that are most at risk, and it works (see 鈥淪ay goodbye to cheap chicken鈥�).
Mathematical models of the 2003 Dutch outbreak show that the old mass slaughter method was only barely enough to stop bird flu spreading where poultry density was high. Vaccination of at least some birds, say the Dutch, tips the balance in our favour. The rest of Europe must move with the times. We have the technology and every reason to use it.
