Microbiology
Summary
Leishmania donovani and Leishmania braziliensis are blood protozoa primarily transmitted through the bite of infected sand flies. In terms of life cycle, the sand fly carries the promastigote form of the parasite. Once inside the host, the parasite becomes an amastigote, typically dwelling inside macrophages.
L. donovani and L. braziliensis cause various forms of leishmaniasis. Leishmania donovani causes a gruesome infection known as visceral leishmaniasis, which is also referred to as black fever or kala-azar. This is a fatal infection if left untreated, with symptoms including skin discoloration, fever, pancytopenia, weakness, and hepatosplenomegaly. On the other hand, Leishmania braziliensis is responsible for the development of cutaneous leishmaniasis, which is characterized by disfiguring ulcers that consume the flesh of its victims. The treatment for these infections depends on the type - cutaneous leishmaniasis is typically treated with stibogluconate whereas visceral leishmaniasis requires amphotericin B.
Lesson Outline
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FAQs
Leishmania braziliensis and Leishmania donovani are both species of protozoan parasites that cause different forms of leishmaniasis. Leishmania braziliensis primarily causes cutaneous and mucocutaneous leishmaniasis, affecting the skin and mucous membranes, respectively. On the other hand, Leishmania donovani is responsible for visceral leishmaniasis (also known as black fever or kala-azar), which affects internal organs such as the spleen, liver, and bone marrow.
The lifecycle of both Leishmania species involves two hosts Ð the sand fly vector and the human host. In the sand fly's gut, the parasites transform into promastigotes, the motile form. When the infected sand fly bites a human, they can transmit the parasite. Once in the human body, the parasites are ingested by macrophages, where they transform into the amastigote form and multiply.
Both diseases are mainly treated with antiparasitic drugs. Among these, sodium stibogluconate is commonly used for all forms of leishmaniasis. Amphotericin B is another potent drug usually reserved for visceral leishmaniasis because of its side effects. The choice of treatment can be dependent on factors like disease type, extent of disease, and patientÕs immune response.
Cutaneous leishmaniasis, often caused by Leishmania braziliensis, primarily presents with skin ulcers at the site where the sand fly bit the patient. On the other hand, visceral leishmaniasis, caused by Leishmania donovani, affects internal organs and can cause symptoms such as fever, weight loss, enlargement of the spleen and liver and abnormalities in blood counts. Both diseases are serious, but visceral leishmaniasis can be life-threatening if not treated properly.
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