Trypanosoma (Herpetosoma) rangeli Tejera, 1920: study of the effects of the parasite on the vector.

For evaluation of the possible pathogenicity of Trypanosoma (Herpetosoma) rangeli Tejera, 1920 to the triatomid vector, first-stage nymphs of laboratory-bred insects were engorged upon albino mice showing average parasitemias of 2 x 10(6) and 2 x 10(5) trypanosomes/ml blood. The vector strains were: Rhodnius prolixus ("New" strain), Triatoma pallidipennis, and Triatoma vitticeps. An "Old" strain of R. prolixus (maintained 30 years in the laboratory) was also employed to check the effects of laboratory breeding. Other lots of nymphs of the same vector strains were fed on healthy mice as controls. T. rangeli produced intense infections in the gut and hemolymph of all the vector tested, with later differentiation in the salivary glands to metatrypomastigotes that could be transmitted by the bite of the insect and establish infections in healthy mice. No statistically significant differences whatever between infected and control bugs were found for degree of engorgement, percentage or cause of mortality, molting time, oviposition/female, hatching time, percentage of hatching, or duration of life cycle. The possible role of experimental methodology in producing pathology in infected insects, and the epidemiological significance of a strain of T. rangeli non-pathogenic to the vector are discussed.