But health authorities barely raised an eyebrow, because it was not thought that an avian 'flu virus could cross over to humans. After all, the H5N1 strain of avian 'flu virus found to be the source of the strain that caused the chicken deaths had been isolated in China's Guandong province a year earlier, and was found to be harmless to ducks and geese. And viruses, although extremely adaptable, need special conditions to be able to take on the genetic make-up that makes them dangerous to people. The unwitting agents suspected of giving the H5N1 virus an opportunity to infect humans were pigs. Pigs the unwitting hosts Pigs are susceptible to both bird and human 'flu viruses, and it is thought the H5N1 avian 'flu virus infected a pig at the same time as a human 'flu virus.
Viruses have only eight genes.
Within weeks the first human victim was in intensive care, and all of a sudden the world had been rudely introduced to the deadly chicken 'flu. In Asia, the inhabited areas are densely populated, often with dubious sanitation. Humans and animals often live in close quarters. Two years ago in Malaysia the bat-borne Nipah virus crossed over to pigs before causing a minor epidemic in humans, killing more than 100 people, many of whom worked in pig abattoirs. The stable hand survived, but trainer Vic Rail died.