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Chapter 56 : At the Level of Cowpats
Researchers sought to determine in what form and numbers Escherichia coli is disseminated from cowpats. Studies demonstrated a clear and predictable correlation between the level of fecal coliforms in cowpats and in runoff water. After taking samples for E. coli counts, they then placed each fresh cowpat under an overhead nozzle delivering simulated rainwater; 20 minutes later, they switched off the simulator and collected all the runoff water for analysis. They fractionated the water to determine the proportions of bacteria adhering to solid particles, the New Zealanders found that around 92% of the organisms were present as individual cells. Not only were few bacteria attached to particles, but there was also no evidence of flocculation. Researcher now know that measures to reduce the level of intestinal bacteria in overland flow on farms need to entrap not only particulate matter, but also single bacterial cells. An example of elemental simplicity comes from the field of influenza virus research, which in recent years has focused on the emergence of the H5N1 avian flu and its potential threat to the human population.