Ferrets of Mass Destruction

The big question for virologists in recent years is why H5N1 influenza hasn’t mutated to cause a pandemic. It is as feeble today at spreading from person to person as it was in 1997, when it first drew attention to itself through a dramatic chicken-to-human outbreak in Hong Kong. H5N1 human infections are very nasty with a high mortality, But they are very hard to catch. To start growing, the virus has to get deep into the lungs. The surest way for this to happen is to be a South East Asian cockfighter. They stimulate the birds by spitting down their throats; the birds spit back.

Ron Fouchier, a virologist at the Erasmus Medical Centre, Rotterdam, has caused a controversy by creating an H5N1 virus in the laboratory that can spread easily from ferret to ferret. In general, flu behaves in them as it does in humans. So his new virus could have the potential to cause a pandemic with a 60 per cent mortality. Another group of virologists have done the same and would like to publish their findings. But the US National Science Advisory Board for Biosecurity is concerned. It wants the scientists’ methods and gene sequences to be redacted, because to publish in full would aid terrorists.

According to information already available, however, Fourchier essentially generated his new virus using the 19th-century approach of growing it in an animal over and over again. After ten transfers, the virus had adapted to ferrets. This experiment does not need complex laboratory facilities. An egg incubator, a supply of fertilised hens eggs and a syringe are all that are needed. I grew litres of virus this way when I used to work on bird flu. And ferrets are freely available: my great-uncle used them to hunt rabbits. The most difficult task would be getting some H5N1 virus.

Fourchier has identified five mutations in two genes that are responsible for the change in the virus. Knowing what they are could be a vitally important tool in the rapid detection of new H5N1 strains in the wild with significant pandemic potential. And if terrorists wanted to hot up H5N1 they would be much more likely to use the ferret approach than genetic engineering based on gene sequences. So the sequences should be published: the benefit to public protection greatly outweighs the risk. If they are seriously concerned about the terrorist threat from flu, MI5 should consider keeping an eye on anyone who buys an egg incubator, and recommend that the government introduce a ferret licensing scheme.