Is the amastigote form of Leishmania the only form found in humans infected with cutaneous Leishmaniasis?

Abstract

Background: Previous studies of Leishmania revealed that 2 forms of the parasite are present: the intracellular amastigote form found in the vertebrate host, and the promastigote form predominately found in the insect vector. Methods: Samples were collected from the lesion area of the skin of 42 patients referred to the laboratory and microscopic slides were prepared. Results: Out of 42 cases, only 1 (2.4%) showed the presence of the amastigote intracellularly alone but not in the extracellular area, and 2 (4.75%) showed the presence of the amastigote in the extracellular but not in the intracellular location. In 20 of 42 cases (48%), we observed the amastigote presence in the intracellular or extracellular area. Out of all 20 cases in which the amastigote was recovered, we were able to identify the amastigote in 17 cases (85%) in the intracellular and extracellular locations simultanously. Additionally, out of all 42 cases referred, the amastigote form alone, with no promastigote associated, was microscopically recovered in 10 cases (24%). Conclusion: Contrary to previous studies, we found that in the human body Leishmania does not act as an obligatory intracellular parasite. Leishmaniais an intracellular and extracellular parasite infecting the mononuclear phagocyte first. There, it remains in the form of amastigote and multiplies by binary fission. When released from the mononuclear phagocyte, after membrane rapture to the extracelluler fluid, the amastigote transforms into a promastigote-like form in a progressive sequence. At a later stage, this promastigote like organism continues its development and transforms again to produce pseudofiber, leaving the lesion area with a permanent scar.