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Session 3: Pathogens and human infectious disease

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This is as a pictorial life cycle diagram with brief descriptions of each stage in the cycle. Egg-containing segments from the adult tapeworm that is present in the gut of a pig or human host contaminate soil, grass and unwashed vegetables. Humans can therefore ingest the tapeworm eggs, and these hatch into larvae in the gut. The larvae may develop into adult tapeworms, which then reside in the gut. Some larvae may get into the bloodstream and go on to form cysts in the person’s muscles, eyes or brain. Similarly, the pig can consume the tapeworm eggs and these may develop into cysts in the pig’s muscle. So, if a human eats undercooked pork, in which the encysted tapeworm may remain alive, the cyst may go on to develop into an adult tapeworm in their gut.