TRYPANOSOMA-CRUZI IN THE RECTUM OF THE BUG TRIATOMA-INFESTANS - EFFECTS OF BLOOD INGESTION OF THE VECTOR AND ARTIFICIAL DIURESIS

The population density and the percentage of different developmental s tages of an established infection of Trypanosoma cruzi were determined at 40 days after the last feeding of the fourth instar in the rectum (lumen, anterior and posterior wall) of fed and unfed groups of fifth instars of Triatoma infestans. Additionally, the rectum and the Malpig hian tubules were incubated in saline, inducing diuresis by addition o f the diuretic hormone. The rectum contained an average of 200,000-400 ,000 T. cruzi. After feeding the percentages of spheromastigotes and d rop-like intermediate stages were reduced from <7% and 15%, respective ly, to <3%, but those of slender intermediate stages increased statist ically significantly from <7% to 10%. After 4 h of diuresis the in-vit ro-incubated isolated rectum with the four Malpighian tubules showed t he same trends, indicating that diuresis rather than factors of the he molymph or digestive products induces the development of metacyclic tr ypomastigotes of T. cruzi originating from epimastigotes.