In vivo differentiation of Trypanosoma cruzi - 1. Experimental evidence of the influence of vector species on metacyclogenesis

Abstract

Vector species has not hitherto been studied as influencing metacyclogenesis of Trypanosoma cruzi, while the role of the parasite strain has been frequently stressed as of dominant importance in this process. In order to fill this gap in our knowledge, metacyclogenesis was monitored in nine triatomine species. The first part of this paper presents photographs of the main and intermediate parasite stages in each vector species studied. In the second part of the study the proportional distribution of all these forms, as seen in Giemsa stained smears is summarized, thus providing an opportunity to analyze both: the length of time between the ingestion of the blood trypomastigotes and the appearance of metacyclic forms and the rates of developmental stages leading to these latter. The most remarkable observation was that metacyclogenesis rates in vivo appear to be vector dependent, reaching 50% in Rhodnius neglectus, 37% in its congener R. prolixus and being dramatically lower in the majority of Triatoma species (5% in T. sordida, 3% in T. brasiliensis and 0% in T. pseudomaculata) at the 120th day of infection. These observations suggest that through screening of different vector species it is possible to find some that are capable of minimizing or maximizing metacyclic production.

Prevention of insect-borne disease: An approach using transgenic symbiotic bacteria

“…5) confirm the antiparasitic effects of recombinant cecropin A. The concentration of metacyclic trypomastigotes in the control group of insects (1.4 ϫ 10 5 Ϫ 1.1 ϫ 10 6 parasites͞ml) is consistent with data reported by others for naturally occurring gut numbers of these parasites (16), and indicates successful infection of the insects by trypanosomes. Striking results were obtained from the transgene-bearing insects.…”

Vectorial capacity of Triatoma guasayana (Wygodzinsky & Abalos) (Hemiptera: Reduviidae) compared with two other species of epidemic importance

“…However, the metacyclogenesis of T. cruzi would be more efficient in the genera Rhodnius and Panstrongylus (Perlowagora-Scumlewicz & Carvalho Moreira 1994), and from a comparative study of the differentiation of T. cruzi in various species of triatomines, these authors concluded that there was a direct relationship between Triatominae species and metacyclogenesis. Our data showed a higher production of metacyclic forms in T. infestans compared to T. sordida and T. guasayana, and we did not observe any differences between the different instars of the same species.…”

Correlation between infection rate of triatominies and Chagas Disease in Southwest of Bahia, Brazil: a warning sign?

“…However, in the specimens captured in intradomiciliary environments during our study, no infection has been observed by T. cruzi. Studies show that their presence has low conversion rates for metacyclic trypomastigotes, and in this way, T. pseudomaculata have not been considered an important vector of Chagas disease (Forattini et al 1981, PerlowagoraSzumlewicz andMoreira 1994).…”