Leishmania are dimorphic because they have which two morphologies?

• A. Promastigotes and Amastigotes
• B. Trophozoites and Cysts
• C. Yeasts and Molds
• D. Spores and Hyphae

Answer: (A)

Leishmania exhibit two forms to thrive in two very different environments: the sandfly vector and the mammalian host. In the sandfly, they exist as promastigotes, which are elongated and flagellated, a form suited to the insect’s gut and the transmission during a bite. Once inside a mammal, they shift to amastigotes, which are smaller, rounder, and non-flagellated, residing and multiplying inside macrophages within phagolysosomes. This switch between a flagellated insect stage and an intracellular non-flagellated mammalian stage is why the parasite is described as dimorphic. So, the two morphologies are promastigotes and amastigotes. Other pairs like trophozoites and cysts or yeasts and molds belong to different organisms or contexts and do not describe Leishmania’s forms.