EXCRETION OF PROMASTIGOTOS OF LEISHMANIA- PIFANOI BY EXPERIMENTALLY INFECTED LUTZOMYIA-YOUNGI

The increase in the promastigotes population of Leishmania pifanoi in Lutzomyia youngi experimentally infected and kept on 50% sacarose unde r constant conditions of temperature and humidify is described. Two st ages in the differentation and growth of the parasites are recognised between two and twenty-four hours after meals. The pleomorphic differe ntiation of the amastigotes in short promastigotes which multiply by b inary division for 60 hours, when the rupture of the peritrophic membr ane occurs, takes place within 48 hours. The second stage occurs betwe en 72 and 96 hours when some of the parasites migrate to the esophagic valve and the rest of the free parasites are excreted in fecal drops as large, active promastigotes. The first drops excreted react positiv ely to glucose or contain crystals of urate. The excess promastigotes of the second stage of development are eliminated in the last excretio ns and react positively to the Hemoscreen and Biuret tests for total p roteins as also for glucose and account for 82% of the of drops excret ed. The excretion of parasites by Lu, youngi is a normal stage in the growth of L. pifanoi into a vector.