Trypanosoma rangeli parasite-vector-vertebrate interactions and their relationship to the systematics and epidemiology of American trypanosomiasis

Introduction. Trypanosoma rangeli is a species of trypanosome second to T. cruzi, that is infective to humans in Latin America. Variability in the biological, biochemical and molecular characteristics between different isolates isolates of this parasite have been recorded. Objective. Morphological and molecular characteristics were recorded from strains of T. rangeli that were isolated from different species of Rhodnius and maintained in different vertebrate species. Materials and methods. Nineteen strains of T. rangeli were isolated from R. prolixus, R. pallescens and R. colombiensis in Colombia, R. ecuadoriensis in Peru and R. pallescens in Panama. Polymorphism of blood trypomastigotes in ICR mice was evaluated and pleomorphism of P53 strain of T. rangeli KP1(-) inoculated in mouse, marsupial and canine was studied. RAPID analysis (randomly amplified polymorphic DNA analysis) of 12 strains isolated from four species of Rhodnius was performed. Result. Based on the total length of blood trypomastigotes, three discrete groups were observed. The P53 strain showed significant differences in the size of blood trypomastigotes in mouse, marsupial and canine. RAPID analysis showed that the strains segregated into two branches corresponding to strains of T. rangeli KP1 (+) and T. rangeli KP1 (-). All strains of T. rangeli KP1 (-) clustered according to the species of Rhodnius from which they were isolated. Conclusion. These data reveal, for the first time, a close association amongst T. rangeli strains and Rhodnius species, confirming that each species of Rhodnius transmits to vertebrate hosts a parasite population with clear phenotypic and genotypic differences. This is further evidence that supports the concept of clonal evolution of these parasites.