Parasites pose a problem for the semantically-oriented microbiologist. There is no question that unicellular parasites such as Giardia, Plasmodium, or Toxoplasma are microbes, thus we can appropriate them with impunity. But what about parasitic worms? They are clearly not microscopic* and are taxonomically apart from parasitic protist. Yet parasitic protists and metazoans are taught alongside one another in the microbiology classroom and they are often considered in unison by epidemiologists and others. For all their phylogenetic divide and apparent differences, they all share the general traits of a parasitic life style, including undergoing the same steps in pathogenesis (encounter with the host, entry, survival, multiplication, causing damage) and eliciting complex immune responses.
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