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🦠microbiology review

African trypanosomiasis

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

African trypanosomiasis, also known as sleeping sickness, is a parasitic disease caused by the protozoan Trypanosoma brucei and transmitted by the tsetse fly. It primarily affects the nervous system and can lead to severe neurological complications if left untreated.

5 Must Know Facts For Your Next Test

  1. African trypanosomiasis is endemic to sub-Saharan Africa, with the majority of cases occurring in the Democratic Republic of the Congo.
  2. The disease progresses in two stages: an early hemolymphatic stage and a late meningoencephalitic stage, which involves the invasion of the central nervous system.
  3. Symptoms in the early stage include fever, headaches, joint pain, and swollen lymph nodes, while the late stage is characterized by neurological manifestations such as sleep disturbances, confusion, and eventually coma.
  4. Diagnosis involves the detection of the Trypanosoma parasites in the blood, lymph, or cerebrospinal fluid, often requiring specialized techniques like microscopy or molecular tests.
  5. Treatment options for African trypanosomiasis are limited, with medications such as pentamidine, suramin, melarsoprol, and eflornithine used depending on the stage of the disease.

Review Questions

  • Describe the life cycle of the Trypanosoma brucei parasite and how it is transmitted to humans through the tsetse fly vector.
    • The Trypanosoma brucei parasite has a complex life cycle that involves both the tsetse fly and the human host. When an infected tsetse fly takes a blood meal from a human, it injects the infective stage of the parasite, known as the metacyclic trypomastigote, into the human's skin. These parasites then enter the bloodstream and lymphatic system, where they multiply and eventually cross the blood-brain barrier to invade the central nervous system. The tsetse fly becomes infected by ingesting the parasite's bloodstream form, known as the trypomastigote, during a blood meal from an infected human or animal. Inside the fly, the parasites undergo further development and transformation, ultimately becoming the infectious metacyclic stage that can be transmitted to the next human or animal host.
  • Explain the two distinct stages of African trypanosomiasis and the associated clinical manifestations in each stage.
    • African trypanosomiasis progresses through two distinct stages. The early, hemolymphatic stage is characterized by non-specific symptoms such as fever, headaches, joint pain, and swollen lymph nodes. This stage is caused by the proliferation of the Trypanosoma brucei parasites in the bloodstream and lymphatic system. As the disease progresses, the parasites cross the blood-brain barrier and invade the central nervous system, leading to the late, meningoencephalitic stage. This stage is marked by neurological manifestations, including sleep disturbances, confusion, coordination problems, and eventually, coma. The invasion of the brain and spinal cord by the parasites triggers a severe inflammatory response, known as neuroinflammation, which contributes to the debilitating neurological symptoms observed in the late stage of the disease.
  • Discuss the challenges associated with the diagnosis and treatment of African trypanosomiasis, and the importance of early intervention for improved patient outcomes.
    • Diagnosing African trypanosomiasis can be challenging, as the early symptoms are non-specific and can be easily mistaken for other tropical diseases. Specialized techniques, such as microscopic examination of blood or cerebrospinal fluid samples, are often required to detect the presence of Trypanosoma brucei parasites. The progression of the disease to the late, neurological stage further complicates diagnosis, as the parasites have already invaded the central nervous system. Treatment options for African trypanosomiasis are limited, and the medications used can have significant side effects, especially in the late stage of the disease. Early intervention is crucial, as the treatment is more effective and less toxic when administered during the early, hemolymphatic stage. Delayed diagnosis and treatment can lead to irreversible neurological damage and a higher risk of mortality. Therefore, improving access to diagnostic tools and effective treatment regimens, as well as raising awareness about the disease, are essential for reducing the burden of African trypanosomiasis and improving patient outcomes.