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Session 3: Pathogens and human infectious disease

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This is as a pictorial life cycle diagram of the malarial protist with brief descriptions of each stage in the cycle. When an infected mosquito bites a person to take a blood meal, mature protists, present in the mosquito’s saliva, get into that person’s bloodstream. They travel in the bloodstream to the liver, enter the liver cells and divide to produce many immature forms. These immature protists invade red blood cells and reproduce themselves. Protists are shed from the RBC and go on to invade further RBCs so their numbers increase rapidly. A mosquito that takes a blood meal from the infected person therefore picks up immature protists. These mature in the mosquito’s gut, and when the mosquito takes its next blood meal from another person it passes on the mature protists to that person, completing the cycle.