'Wild animals lived in their natural environment.' 'So, viruses could not be communicated.' 'Then came mass production and mass quartering of animals -- whether it be poultry, pigs and cattle -- which gave rise to bird flu, SARS and the mad cow disease.' 'Vast amounts of animal produce are also being flown from one part of the world to another, which has helped to spread the virus.' 'All these changes have led to a new and deadly mutation of the virus that has immobliised human beings.'