The effect ofBlastocrithidia triatomae(Trypanosomatidae) on the midgut of the reduviid bugTriatoma infestans

Abstract

SummaryThe pathogenic flagellateBlastocrithidia triatomaedisrupts the digestion ofTriatoma infestans; the midgut ultrastructure of bugs infected with the flagellate and of uninfected bugs is compared. Third or fourth instar larvae were dissected either unfed or 1 week after feeding.In all uninfected bugs extracellular membrane layers (e.m.l.) covered the apical microvillar border of the epithelial cells. Some midgut regions of bugs infected withB. triatomaeappeared normal but often adjacent cells showed pathological effects. In affected cells the e.m.l. and the microvilli and finally the cells themselves were reduced or destroyed. Correlated with these observations of pathogenicity the method of attachment of parasites changed. When the e.m.l. were present only rarely were flagella found, but on extracellular membrane-free cellsB. triatomaeattached by flagellar enlargement to the microvillar border or, if this was reduced, to the apical host cell membrane. No hemidesmosome-like plaques were found at the attachment site. Although some flagella were inserted into the apical region of the cells no intracellular flagellates were observed.