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🦠microbiology review

Leishmania donovani

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

Definition

Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis, also known as kala-azar, a severe and potentially fatal form of leishmaniasis. It is transmitted to humans through the bite of infected sand flies and primarily affects the circulatory and lymphatic systems.

5 Must Know Facts For Your Next Test

  1. Leishmania donovani is a protozoan parasite that belongs to the genus Leishmania and is the causative agent of visceral leishmaniasis, also known as kala-azar.
  2. The parasite is transmitted to humans through the bite of infected female sand flies, which feed on the blood of humans and other mammals.
  3. Leishmania donovani primarily affects the circulatory and lymphatic systems, leading to the development of visceral leishmaniasis, a systemic disease characterized by fever, weight loss, enlargement of the spleen and liver, and anemia.
  4. Kala-azar is the most severe form of visceral leishmaniasis caused by Leishmania donovani, and it can be fatal if left untreated.
  5. Diagnosis of Leishmania donovani infection typically involves serological tests, such as the rK39 rapid diagnostic test, or the detection of the parasite in tissue samples.

Review Questions

  • Describe the life cycle of Leishmania donovani and how it is transmitted to humans.
    • The life cycle of Leishmania donovani involves two main stages: the promastigote stage in the sand fly vector and the amastigote stage in the human host. When an infected sand fly takes a blood meal from a human, it injects the promastigote form of the parasite into the skin. The promastigotes are then phagocytized by macrophages, where they transform into the amastigote form and multiply. The amastigotes can then be transmitted to other sand flies during their blood meal, completing the life cycle. This transmission process is crucial for the spread of Leishmania donovani and the development of visceral leishmaniasis in humans.
  • Explain the pathogenesis of visceral leishmaniasis caused by Leishmania donovani and its impact on the circulatory and lymphatic systems.
    • Leishmania donovani primarily targets the cells of the reticuloendothelial system, including macrophages, which are found in the liver, spleen, and bone marrow. The amastigote form of the parasite multiplies within these cells, leading to their destruction and the release of more parasites. This process causes the enlargement of the spleen and liver, as well as the disruption of normal immune function. The parasite's invasion of the circulatory and lymphatic systems can lead to the development of fever, weight loss, anemia, and other systemic symptoms associated with visceral leishmaniasis. The progressive damage to these critical systems can be life-threatening if the infection is not properly diagnosed and treated.
  • Evaluate the importance of early diagnosis and appropriate treatment for Leishmania donovani infection in the context of parasitic infections of the circulatory and lymphatic systems.
    • Prompt diagnosis and effective treatment of Leishmania donovani infection are crucial in preventing the progression of visceral leishmaniasis and its potentially fatal consequences. Early detection of the parasite through serological tests or tissue sample analysis allows for timely intervention, which can significantly improve patient outcomes. Appropriate treatment, typically with antiparasitic drugs, can help to eliminate the Leishmania donovani parasites, reduce the burden on the circulatory and lymphatic systems, and prevent the development of severe complications. Failure to diagnose and treat Leishmania donovani infection in a timely manner can lead to the continued proliferation of the parasite, further damage to the affected systems, and a higher risk of mortality. Therefore, understanding the importance of early diagnosis and treatment is crucial in the context of parasitic infections of the circulatory and lymphatic systems.