Susceptibility of different Rhodnius species (Hemiptera, Reduviidae, Triatominae) to a Brazilian strain of Trypanosoma rangeli (SC58/KP1-)

Abstract

Introduction: Specific host-parasite associations have been detected experimentally and suggest that triatomines of the genus Rhodnius act as biological filters in the transmission of Trypanosoma rangeli.
Objective: To analyze the susceptibility of four Rhodnius species (Rhodnius robustus, Rhodnius neglectus, Rhodnius nasutus and Rhodnius pictipes) to a Brazilian strain of T. rangeli (SC-58/KP1-).
Materials and methods: We selected thirty nymphs of each species, which were fed on blood infected with T. rangeli. Periodically, samples of feces and hemolymph were analyzed. Triatomines with T. rangeli in their hemolymph were fed on mice to check for transmission by bites. Later, the triatomines were dissected to confirm salivary gland infection.
Results: Specimens of R. pictipes showed higher rates of intestinal infection compared to the other three species. Epimastigotes and trypomastigotes were detected in hemolymph of four species; however, parasitism was lower in the species of the R. robustus lineage. Rhodnius robustus and R. neglectus specimens did not transmit T. rangeli by bite; after dissection, their glands were not infected. Only one specimen of R. nasutus and two of R. pictipes transmitted the parasite by bite. The rate of salivary gland infection was 16% for R. pictipes and 4% for R. nasutus.
Conclusions: Both infectivity (intestinal, hemolymphatic and glandular) and transmission of T. rangeli (SC58/KP1-) were greater and more efficient in R. pictipes. These results reinforce the hypothesis that these triatomines may act as biological filters in the transmission of T. rangeli.