Cutaneous And Mucocutaneous Leishmaniasis
Modes of Transmission :
Vector-borne: by bite of infected female sandflies (2–3 mm long), which become infected by taking blood meal from infected mammalian host.
Other modes: congenital and parenteral (i.e., by blood transfusion, needle sharing, laboratory accident).
Incubation Period: Inversely proportional to size of inoculum: shorter in visitors to endemic area. OWCL:
L. tropica major : 1–4 weeks.
L. tropica , 2–8 months.
acute CL: 2–8 weeks or more.
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Epidemiology
• Etiology :
Infection in humans is caused by ∼20
Leishmania species ( Leishmania and Viannia
subgenera).
• Stages of Parasite:
• Promastrigote: flagellated form found in
sandflies and culture.
• Amastigote: nonflagellated tissue form (2–4
μm in diameter); replicates in macrophage
phagosomes in mammalian hosts.
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Modes of Transmission :
1)Vector-borne: by bite of infected female
sandflies (2–3 mm long), which become
infected by taking blood meal from infected
mammalian host.
2)Other modes: congenital and parenteral
(i.e., by blood transfusion, needle sharing,
laboratory accident).
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Immune status of person
• Leishmania-specific anergy : patients
develop DCL(diffuse cutaneous leishmaniasis).
• Poor immune response or
immunosuppression (HIV/AIDS): VL (visceral
leishmaniasis).
• Hyperergic variant: Leishmaniasis
recidivans caused by L. tropica .
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Clinical Manifestation
• Incubation Period: Inversely proportional
to size of inoculum: shorter in visitors to
endemic area. OWCL:
• L. tropica major : 1–4 weeks.
• L. tropica , 2–8 months.
• acute CL: 2–8 weeks or more.
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Skin Findings
• Types of Lesions Primary lesions occur at site
of sandfly bite, usually on exposed site.
1. OWCL (Old World cutaneous leishmaniasis) L. major:
Begins as small erythematous papule, which
may appear immediately after sandfly bite but
usually 2–4 weeks later. Papule slowly
enlarges to 2 cm over a period of several
weeks .
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Old World cutaneous leishmaniasis: face
Large crusted nodules with surrounding edema on both
cheeks
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2. L. tropica:
Clinical pattern similar to that of L. major ,
although lesions caused by L. tropica are
more apt to be solitary, more inflammatory,
last longer, and be more difficult to treat.
3. NWCL L. mexicana Complex:
• Small erythematous papule develops at
sandfly bite site, evolving into ulcerated
nodule
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New World cutaneous leishmaniasis:
chiclero ulcer A deep ulcer on the helix at the site of a
sandfly bite
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Diagnosis ?
1) Clinical Diagnosis (Skin lesion )
2) Serology: Lacks specificity. Cannot distinguish
current from past infection.
3) Dermatopathology: Large macrophages filled
with 2- to 4-μm amastigotes (Leishman- Donovan
bodies); mixed lymphocytic, plasmacytic infiltrate. In
Wright- and Giemsa-stained.
4) Culture :Novy-MacNeal-Nicolle (NNN) medium at
22°C–28°C for 21 days grows motile promastigotes.
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4) Needle Aspiration: Visualize
amastigote within macrophages.
5) Polymerase Chain Reaction: Can
detect different species of Leishmania .
Specific and sensitive.
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Course And Prognosis
1) CL : Whether caused by L. tropica or L.
mexicana , CL is self-limited. Scarring is
increased by secondary bacterial infection.
2) MCL: May extend to secondary sites.
Superinfection common. Death from
pneumonia.
3) DCL : Progressive; refractory to treatment;
cures rare.
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Management
1. Prophylaxis:
No chemoprophylaxis for travelers exists.
• OWCL: Delay specific treatment until
ulceration occurs, allowing protective
immunity to develop, unless lesions are
disfiguring, disabling, persist ± 6 months.
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Goals:
Accelerating healing of skin lesions
Decreasing morbidity
Decreasing risk for local and mucosal
dissemination and relapse
Management of Cutaneous
Leishmaniasis
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Lesional Therapy
Effective in some cases without local dissemination or
risk of mucosal dissemination (e.g., for relatively benign
lesions caused by L. Mexicana or L. major ).
Topical imiquimod
Paromomycin ointments (15% paramomycin sulfate,
12% methylbenzethonium chloride in white paraffin twice
daily for 10 days)
Cryosurgery
Ultrasound-induced hyperthermia
Intralesional Pentostam given weekly up to1 mg/kg
injected into borders of lesions)