Trypanosoma cruzi in the rectum of the bug Triatoma infestans: effects of blood ingestion by the starved vector.

Abstract

To follow the developmental effects of feeding of the insect host after long starvation periods, the population density and composition of an established infection of Trypanosoma cruzi in the rectum of Triatoma infestans were determined 60 days after the last feeding (daf) and then at different intervals after feeding. The original population decreased and then increased up to the 10th daf. In starved bugs, about 30% were spheromastigotes (including intermediate forms), 20% epimastigotes, and 50% trypomastigotes, but one daf, these forms represented 2%, 70%, and 10%, respectively. In addition, one daf there were about 10% giant cells, i.e., a multiple division stage. In the following two days, this form represented on average 30-50% of the total population, but it then disappeared nearly completely. Thus, giant cells evidently develop by rapid growth of epimastigotes, if conditions become optimal after long starvation periods of the vector.

Rhodnius prolixus Life History Outcomes Differ when Infected with Different Trypanosoma cruzi I Strains

“…Parasite loads in triatomines are dramatically reduced on ingestion of an uninfected blood meal. 22,26,81 Studies have shown that 1) the number of parasites in an infective blood meal decreases dramatically on ingestion due to digestive enzymes, temperature changes, and the gut microbiota community 48,82 ; and 2) the total trypanosome population size and composition (proportion of each form present) within a triatomine fluctuates according to feeding status; significant decreases in parasite numbers can occur within 4 hours after feeding, by as much as 50% in some parts of the bug 22,26,81 ; and 3) T. cruzi-infective dose does not correlate with the number of parasites excreted. 62,83,84 These studies suggest that the number of parasites ingested is fewer than the number that the insect will face, and that, while it may lead to a temporary effect, this should change by the time the insect excretes parasites and takes its next blood meal.…”

“…[15][16][17][18][19][20] This idea is mainly based on studies of the triatomine species Triatoma infestans. 15,[21][22][23][24][25][26][27] Investigations into the effect of T. cruzi infection on other triatomine species have yielded variable results, with some results suggesting that T. cruzi reduces triatomine survival and or reproduction, [28][29][30][31][32] and others finding little to no effect. [33][34][35] Although some of the discrepancies may be due to differences in experimental conditions or design, it is also possible that the inherent variability of T. cruzi itself is a driver of the variable fitness outcomes in infected triatomines, as it is in its mammal hosts.…”

“…To the best of our knowledge, this has not been tested, as all published studies on the effect of T. cruzi on triatomines have been limited to one T. cruzi strain-I triatomine species system. 15,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Given that a principle focus in Chagas disease prevention is the interruption of T. cruzi transmission by triatomine bugs living in and around human homes, it is important to understand the full range of outcomes that trypanosome infection can have on triatomines. Therefore, we asked, does variability exist in the effect of different T. cruzi strains on its triatomine host?…”

Some morphological and molecular aspects of the life cycle of Trypansoma cruzi in the insect vector

“…In relation to other factors involved in the cycle, some information about the population density of the different morphological stages present in various parts of the intestine of the insect, under certain physiological conditions or time periods, have been published recently (Kollien & Schaub 1997, 1998a. Kollien et al (1998), also confirmed that the flagellates have no tendency to attach themselves by the flagellum to the wall of the midgut as they do in the hindgut.…”

Ultrastructural and physiological changes induced by different stress conditions on the human parasite Trypanosoma cruzi

“…in particular, the lack of food will induce the transformation of epimastigote to trypomastigote (Contreras et al 1985;Kollien and Schaub 1998). Also inside the vector intestine, the parasite will contend with variable pH from 5.7 to 8.9, depending on the amount of food ingested by the vector (Kollien et al 2001).…”