Part of the show Pain and Painkillers, and Chemistry of everyday life
Most people assume that flu is a human virus but it originally came from birds, and the strains of the virus that cause disease in people are slightly different to the strains that cause disease in birds. But occasionally the virus changes, or mutates, and gains the ability to jump the species barrier from birds to infect humans. This happened in Hong Kong in 1997. The virus rapidly gains a foothold and makes these people very unwell because their immune system, which is used to picking up human flu viruses, cannot recognise it the bird version and so the virus has a head start. The present outbreak started in South Korea in December. In Vietnam 6 out of 7 people infected have died, and in Thailand 3 boys have become unwell and 2 have died. All of them had been in contact with poultry. Fortunately, for the moment, although the bird flu can infect a person, it cannot spread from person to person like normal human flu. But doctors are concerned that if a person infected with normal flu also acquires the avian flu the 2 viruses could recombine, or swap pieces of genetic material, to produce a virus with the destructive power of the avian flu, and the ability to spread from person to person. Scientists suspect that this sort of event has given rise to some of the severe flu pandemics that we have seen over the last 100 years, including the 1918 Spanish flu pandemic that killed 20 million people. To tackle the problem doctors this week brought a sample of the deadly bird flu strain to London from Vietnam in a bomb-proof container. They plan to produce a vaccine by combining some of the genetic material from the bird flu with normal human flu to produce a safe vaccine.