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One underlying
reason is that human activities have altered local, regional and global ecosystems[16]. We remain ignorant about many aspects of the
ecology, epidemiology and natural history of some of the new diseases, but our
understanding of others has grown with spectacular speed, a gratifying demonstration of
the power of modern biomedical sciences, notably molecular biology and immunology. But the
microbes are clever too, and some well-known ones have lately found new ways to challenge
us, sometimes aided by features of modern civilization.
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