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What is the primary mode of transmission for visceral leishmaniasis in Sudan?
What is the primary mode of transmission for visceral leishmaniasis in Sudan?
During the pathogenesis of visceral leishmaniasis, the form of the parasite that replicates inside macrophages is called:
During the pathogenesis of visceral leishmaniasis, the form of the parasite that replicates inside macrophages is called:
Which of the following clinical manifestations is associated with visceral leishmaniasis?
Which of the following clinical manifestations is associated with visceral leishmaniasis?
What is the incubation period for visceral leishmaniasis?
What is the incubation period for visceral leishmaniasis?
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Which laboratory method is NOT typically used for the diagnosis of visceral leishmaniasis?
Which laboratory method is NOT typically used for the diagnosis of visceral leishmaniasis?
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The Montenegro test is primarily used to assess which of the following?
The Montenegro test is primarily used to assess which of the following?
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Which cytokine is NOT released during the immune response to visceral leishmaniasis?
Which cytokine is NOT released during the immune response to visceral leishmaniasis?
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Which factor contributes to hypersplenism in visceral leishmaniasis?
Which factor contributes to hypersplenism in visceral leishmaniasis?
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What is the primary vector responsible for transmitting Leishmaniasis?
What is the primary vector responsible for transmitting Leishmaniasis?
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Which form of Leishmaniasis is associated with L.brasiliensis?
Which form of Leishmaniasis is associated with L.brasiliensis?
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What is the typical incubation period for Cutaneous Leishmaniasis caused by L.tropica?
What is the typical incubation period for Cutaneous Leishmaniasis caused by L.tropica?
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Which of the following morphological forms is flagellated?
Which of the following morphological forms is flagellated?
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Which of these species is NOT a common cause of Cutaneous Leishmaniasis?
Which of these species is NOT a common cause of Cutaneous Leishmaniasis?
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What characterizes the chronic form of Cutaneous Leishmaniasis in individuals with decreased immunity?
What characterizes the chronic form of Cutaneous Leishmaniasis in individuals with decreased immunity?
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What type of hypersensitivity reaction is associated with the symptoms of Cutaneous Leishmaniasis?
What type of hypersensitivity reaction is associated with the symptoms of Cutaneous Leishmaniasis?
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Which diagnostic method is NOT applicable for identifying Cutaneous Leishmaniasis?
Which diagnostic method is NOT applicable for identifying Cutaneous Leishmaniasis?
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Study Notes
Leishmaniasis Definition
- Leishmaniasis is a group of diseases caused by different species of protozoa within the genus Leishmania. These protozoa are flagellated.
Parasitology
- Genus: Leishmania
- Species: L. Tropica, L. donovani, L. major
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Morphological Forms:
- Amastigote: Also known as LD body, a non-flagellated form.
- Promastegote: A flagellated form, found only in the fly or in culture.
Life Cycle
- Transmission occurs through the bite of blood-feeding sand flies (Phlebotomus).
- The promastigote is carried in the fly's anterior gut and pharynx.
- The parasite enters mononuclear phagocytes, transforming into amastigotes.
- Amastigotes multiply until the infected cell ruptures, releasing organisms into the bloodstream.
- Sand flies acquire the organisms during blood meals, and the amastigotes transform into promastigotes, multiplying in the fly's gut.
- Dogs and rodents are common animal reservoirs.
Epidemiology
- Leishmaniasis is endemic in various geographical areas, notably parts of the Americas, the Mediterranean region, and Asia.
- Specific maps display the endemic areas.
Leishmaniasis: The Disease
- Three major groups/complexes:
- Leishmania Tropica Complex: Results in cutaneous leishmaniasis.
- Leishmania Brasiliensis: Causes mucocutaneous leishmaniasis.
- Leishmania Donovani: Leads to visceral leishmaniasis.
Cutaneous Leishmaniasis
- Two forms of cutaneous leishmaniasis:
- Old World: L. tropica major, L. tropica minor, L. aethiopica
- New World: L. mexicana, L. brasiliensis
- Symptoms: Starts as a red papule, often itching, due to a Type IV hypersensitivity response. It may be complicated by a secondary bacterial infection.
- Clinical Course: Lesions are typically self-healing, progressing from papule to crateriform ulcer to scar.
- Microscopic Findings: Dermal tissue contains amastigotes. Lymphocytes and plasma cells infiltrate the area. Tissue necrosis is present. Granulomas are observed.
- Diagnosis: Clinical evaluation, epidemiological factors, skin smear/scrape/biopsy to identify LD bodies, and culture on NNN (Novy–MacNeal–Nicolle) medium.
- Geographic Distribution: Common in the Mediterranean region and Middle East.
Mucocutaneous Leishmaniasis
- Cause: Leishmania brasiliensis complex.
- Distribution: Less common in Sudan than in South America.
- Transmission: Transmitted by the Lutzomyia sand fly.
Pathology and Clinical Features of Mucocutaneous Leishmaniasis
- Starts as a cutaneous lesion that has metastatic lesions in mucocutaneous junctions (e.g., lips, nose).
- Lesions may expand or deepen, destroying mucous membranes (mucosa and underlying tissues).
- Healing may lead to erosion of mucosa and cartilage, but not bone.
- Secondary bacterial infections are often observed.
Visceral Leishmaniasis (Kala-azar)
- Transmission: Primarily by Phlebotomus orientalis sand fly in Sudan, with wild animals serving as reservoirs.
- Transmission Routes: Other transmission routes include blood transfusion, vertical transmission (congenital), sexual contact, and direct contact (less common).
Pathogenesis of Visceral Leishmaniasis
- The parasite enters the host through a skin bite, transforming from promastigote to amastigote (LD bodies).
- LD bodies spread to lymph nodes and RES (reticuloendothelial system).
- Parasites replicate inside macrophages.
- Cytokines (TNF, IL-1, IL-6, bradykinin) are released.
Pathology of Visceral Leishmaniasis
- Organ Involvement: Damage to liver (Kupffer cell hyperplasia), bone marrow (infiltration), and spleen.
- Spleen: Red pulp hyperplasia, with a potential for hypersplenism and pancytopenia (low levels of blood cells).
- Lymphatic Tissue: Reactive lymphadenopathy.
Clinical Manifestations of Visceral Leishmaniasis
- Incubation Period: 3 to 6 months.
- Symptoms: Chronic fever (with possible double peaks), sweating, chills, weight loss, good appetite, watery diarrhea, and general weakness.
- Advanced Symptoms: Massive enlargement of spleen and liver (splenomegaly, hepatomegaly), nasal bleeding (epistaxis), and secondary infections.
- Additional Manifestations: Skin discoloration (dyspigmentation), pneumonia, dysentery, tuberculosis.
Laboratory Diagnosis of Visceral Leishmaniasis
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Methods:
- Identification of amastigotes (LD bodies) in aspirated materials (spleen, bone marrow, lymph nodes) through smears.
- Microscopic examination of tissue samples from ulcers obtained from cutaneous or mucocutaneous lesions.
- Culture using Novy–MacNeal–Nicolle (NNN) medium, typically yielding results within 1–3 weeks.
- Serologic tests (e.g., direct agglutination test [DAT], rK39 ICT, indirect fluorescent antibody test [IFAT], ELISA).
- Polymerase chain reaction (PCR)
Laboratory Diagnosis of Leishmaniasis (General)
- Other Tests: Complete blood count, liver function tests (LFTs), coagulation panel, and evaluation of immunoglobulins (hypergammaglobulinemia).
Leishmanin Skin Test (Montenegro Test)
- Timing: Positive results appear 3 months after lesion development.
- Procedure: Intradermal injection of killed promastigotes followed by evaluation of skin 48 hours later for delayed-type hypersensitivity response.
- Positive Result: Induration of 5 mm or more indicating a positive response to the test.
- Positive Results Observed In: In people with resolving infections, individuals successfully treated with chemotherapy for cutaneous leishmaniasis.
Complications of Visceral Leishmaniasis
- Infections: Specific examples include dysentery, tuberculosis, and pneumonia.
- Amyloidosis
- Pancytopenia: Caused by bone marrow infiltration and hypersplenism.
- Cancrum oris: A severe form of oral infection.
- Eye Complications: Retinal hemorrhage, papilledema
Post-Kala-azar Dermal Leishmaniasis (PKDL)
- Post-treatment Reactions: Allergic reactions (e.g., local hypersensitivity response or Arthus reaction).
- Clinical Features: Skin nodules and increased pigmentation.
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Description
This quiz covers the definition, morphological forms, and life cycle of Leishmaniasis, a disease caused by the Leishmania genus. Participants will explore the transmission through sand flies and understand the epidemiology associated with this parasite.
