Explore how our bodies are designed to prevent potentially harmful objects from getting inside, and what happens when foreign organisms or substances breach these barriers.
For many kinds of organism, the human body is a perfect environment in which to live. We have learned to cope with the presence of most organisms that like to live inside us, but some are harmful or deadly. In this article, learn the major types and examples of different human pathogens: virus, bacterium, parasite, fungus and prion protein.
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Each issue of 'Big Picture' comes with a sprinkling of Fast Facts, fascinating snippets of information on the topic covered.