The pathogen s path
Several strains of influenza or flu have been named after Guangdong province, where the first sars cases surfaced. This dubious distinction stems from the agricultural practices prevalent in the region. Rice fields support ducks and chickens, which feed on pig waste. The waste of one becomes the food of the other, resulting in a perfectly self-sufficient nutrient cycle. Helped by their ability to exist in faecal matter, conditions become ideal for viruses to evolve very quickly in different animals.
Luis Villarreal, director, Center for Virus Research, University of California, Irvine, usa, believes that China's otherwise ecologically sound agricultural systems facilitate recombination between silent viruses in farmed species and other organisms. This, he says, increases the likelihood of the emergence of new human infectious agents. "The domestication of the duck has brought a