Introduction:

Regional hyperthermia at between 38 and 39.5 °C has been used to treat inflammatory processes and, occasionally, skin infections. In areas where leishmaniasis is endemic, hot compresses are applied as anti-parasitic treatment.

Objective:

To identify the bases of leishmaniasis thermal treatment in order to properly regulate it.

Methods:

In vitro-cultured Leishmania mexicana parasites were incubated for variable periods at 37 and then, to 25 °C. The parasites were then stained with Annexin V-FITC to detect apoptosis induction and with propidium iodide for viability. Post-treatment growth curves and cell cycle identification with anti-cyclin antibodies were performed.

Results:

After 30 minutes of exposure to a temperature of 37 °C, a variable proportion of parasites lost their characteristic oval shape and became spherical, without refringence and with condensed nuclei, with these changes suggesting apoptosis, which was confirmed by Annexin V-FITC staining. The number of parasites that underwent apoptosis was proportional to exposure time. Parasites in which apoptosis was observed were stained with anti-cyclin antibodies.

Conclusions:

Constant, regulated and physiological elevation of temperature for more than 30 minutes induces apoptosis of in vitro-cultured L. mexicana parasites when they are in an active phase of the cell cycle.