Merck Manual

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Life Cycle of Trypanosoma brucei gambiense
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Life Cycle of Trypanosoma brucei gambiense
    • 1. When an infected tsetse fly bites a person (or animal), it injects a form of the protozoa that can cause infection (called trypomastigotes) into the skin. The protozoa move to the lymphatic system and bloodstream.

    • 2. Inside the person, they change forms and travel to organs and tissues throughout the body, including lymph and spinal fluid.

    • 3. The protozoa multiply in the bloodstream and other body fluids.

    • 4. They circulate in the bloodstream.

    • 5. A fly ingests the protozoa when it bites an infected person.

    • 6. Inside the fly, the protozoa change forms and multiply.

    • 7–8. The protozoa travel to the fly's salivary glands, multiply, and change into trypomastigotes—the form that is injected when the fly bites a person.

Image from the Centers for Disease Control and Prevention Image Library.