Cutaneous Leishmaniasis Practice Flashcards

A set of practice flashcards covering morphology, life cycles, clinical pictures, and laboratory diagnosis of Old World and New World Cutaneous Leishmaniasis.

What are the general characteristics and classification basis of Leishmania species?

Leishmania species are obligate intracellular parasites that are classified primarily on the basis of their geographical distribution into Old World and New World species.

Which sandfly genera serve as vectors for Old World and New World leishmaniasis?

Old World leishmaniasis is transmitted by sandflies of the genus Phlebotomus, whereas New World leishmaniasis is transmitted by sandflies of the genus Lutzomyia.

Which species comprise the Leishmania tropica complex, and what disease do they cause?

The Leishmania tropica complex includes Leishmania tropica, Leishmania major, and Leishmania aethiopica. All of these species cause Old World cutaneous leishmaniasis.

What is the habitat of Old World Cutaneous Leishmaniasis parasites in host tissues and vectors?

They are essentially parasites of the skin. Amastigote forms occur in reticuloendothelial cells (histiocytes and endothelial cells) of the skin, whereas promastigote forms occur in the sandfly vector.

How is Old World Cutaneous Leishmaniasis transmitted?

The primary mode of transmission is through the bite of sandflies (Phlebotomus species). Infection can also occasionally occur via direct contact.

What are the causative agent, lesion names, and clinical features of Anthroponotic (Urban) cutaneous leishmaniasis?

It is caused by Leishmania tropica and presents as painless dry ulcers with raised and indurated margins (known as Oriental sore, Delhi boil, Allepo button, or dry ulcer) that heal spontaneously in about a year, leaving disfiguring scars.

What are the causative species and characteristics of Zoonotic (Rural) cutaneous leishmaniasis?

It is caused by Leishmania major and presents as painful, inflamed, moist (wet/weeping) ulcers that heal more rapidly than lesions caused by Leishmania tropica.

What are the causative species and clinical manifestations of Non-ulcerative (Diffuse) cutaneous leishmaniasis?

It is caused by Leishmania aethiopica and presents as widely distributed nodular lesions without ulceration. It is associated with low humoral and cell-mediated immunity, and lesions persist for years or a lifetime.

What is Leishmaniasis recidivans, and what are its key features?

It is a chronic form of cutaneous leishmaniasis occurring in individuals with high cell-mediated immunity. It features alternating activity and healing with a central scar and active margins (resembling tuberculoid leprosy), very scanty parasites, and a strongly positive Leishmanin test.

How is Old World Cutaneous Leishmaniasis diagnosed in the laboratory?

By demonstrating amastigotes inside macrophages from ulcer edge smears, isolating promastigotes by culturing aspirates in NNN medium, and performing the Leishmanin skin test (positive in children under 10 in endemic areas; negative in diffuse forms).

Which parasite complexes cause New World Leishmaniasis, and how are they transmitted?

It is caused by the Leishmania braziliensis complex and Leishmania mexicana complex in Central and South America. Transmission occurs via bites of Lutzomyia sandflies, direct contact, or autoinfection.

What specific clinical lesion is associated with the Leishmania mexicana complex?

The Leishmania mexicana complex causes chiclero ulcer (also known as self-healing sore of Mexico), which is characterized by ulceration on the pinna of the ear.

What clinical manifestation is caused by the Leishmania braziliensis complex?

It causes cutaneous and mucocutaneous leishmaniasis (espundia), involving nodules inside the nose, perforation of the nasal septum, and severe destruction of the nose, lips, mouth, and larynx.

What laboratory diagnostic methods are used for New World Cutaneous and Mucocutaneous Leishmaniasis?

Microscopic demonstration of amastigotes in skin/mucous membrane smears or slit-skin biopsy, promastigote culture in NNN medium, serological detection of antibodies via IFA or ELISA, and a positive Leishmanin skin test.

In a patient returning from Guatemala with an itchy wrist plaque containing central ulceration and intracellular amastigotes on biopsy, what is the causal organism?

Leishmania braziliensis.