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Pathology – Leishmaniasis
Leishmaniasis
pathogen: Leishmania protozoa.
Epidemiology • 1-2 million new cases annually worldwide. • Found in Africa, India, South America, Middle East, and the Mediterranean. Infection can be transmitted through a sandfly bite.
Pathogenesis: • The parasite enters the dermis and is phagocytosed by dermal macrophages. • The ability of each species to live within macrophages and avoid host immunity determines the clinical outcome.
Cutaneous leishmaniasis, caused by Leishmania (L.) tropica and L. Mexicana, typically results in a solitary nodule that ulcerates and heals with scarring.
• L. braziliensis causes mucocutaneous leishmaniasis, which causes skin lesions that can extend to the nose, mouth, and pharynx.
• Visceral leishmaniasis (kala-azar) caused by L. donovani causes fever, anemia, lymphadenopathy, and hepatosplenomegaly. The parasite spreads through macrophages and the reticuloendothelial system.
Diagnosis: Microscopy, culture, FISH, or PCR. Histopathology • Skin biopsies reveal a dense dermal immune infiltrate with lymphocytes, plasma cells, and parasitized macrophages. • The organisms are round to oval, 2-4 micrometers in size, and have an eccentric kinetoplast.
Prognosis: Cutaneous illness often cures spontaneously over months. • Early treatment is crucial for mucocutaneous illness, since mucosal involvement leads to poor outcomes. • Without therapy, visceral illness can lead to liver and bone marrow failure, which is deadly.
Leishmaniasis
pathogen: Leishmania protozoa.
Epidemiology • 1-2 million new cases annually worldwide. • Found in Africa, India, South America, Middle East, and the Mediterranean. Infection can be transmitted through a sandfly bite.
Pathogenesis: • The parasite enters the dermis and is phagocytosed by dermal macrophages. • The ability of each species to live within macrophages and avoid host immunity determines the clinical outcome.
Cutaneous leishmaniasis, caused by Leishmania (L.) tropica and L. Mexicana, typically results in a solitary nodule that ulcerates and heals with scarring.
• L. braziliensis causes mucocutaneous leishmaniasis, which causes skin lesions that can extend to the nose, mouth, and pharynx.
• Visceral leishmaniasis (kala-azar) caused by L. donovani causes fever, anemia, lymphadenopathy, and hepatosplenomegaly. The parasite spreads through macrophages and the reticuloendothelial system.
Diagnosis: Microscopy, culture, FISH, or PCR. Histopathology • Skin biopsies reveal a dense dermal immune infiltrate with lymphocytes, plasma cells, and parasitized macrophages. • The organisms are round to oval, 2-4 micrometers in size, and have an eccentric kinetoplast.
Prognosis: Cutaneous illness often cures spontaneously over months. • Early treatment is crucial for mucocutaneous illness, since mucosal involvement leads to poor outcomes. • Without therapy, visceral illness can lead to liver and bone marrow failure, which is deadly.
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