Leishmania in phlebotomid sandflies V. The nature and significance of infections of the pylorus and ileum of the sandfly by leishmaniae of the braziliensis complex

Abstract

A study of two isolates of Leishmania braziliensis braziliensis in the hindgut of experimentally infected Lutzomyia longipalpis was made with the light and electron microscopes. Infections were always heavier in the pylorus than the ileum, and no parasites were found in the rectum. The parasites became attached to the cuticular intima lining the hindgut by hemidesmosomes formed within the sheath of the flagellum. In parts of the ileum where the lining was in folds, attachment was additionally by the insertion of greatly enlarged flagella which became moulded to fit the folds; large folds were filled with masses of parasites. In both the pylorus and ileum, the parasites were promastigotes, sphaeromastigotes or paramastigotes with a juxtanuclear kinetoplast. Dividing stages were common. It is thought that the unique development of the braziliensis complex in the pylorus and ileum of the sandfly is simply the preliminary establishment of an infection where the parasites initially multiply before migrating forwards to the foregut and proboscis; it is comparable to the establishment of infection in the midgut by other mammalian leishmaniae.