An isoenzyme study of naturally occurring clones of Trypanosoma cruzi isolated from both sides of the West Andes highland.

Seventy-two stocks of Trypanosoma cruzi isolated from both sides of the West Andes highland (Bolivia, Chile and Peru) were analysed by isoenzyme electrophoresis at 12 loci. The data, which were interpreted in terms of population and evolutionary genetics, corroborated the hypothesis of T. cruzi clonal population structure previously proposed, and indicated extensive genetic variability within the taxon T. cruzi. Fifteen different clones (or zymodemes) were identified, which could be grouped into 3 different clusters. Several clones from 2 of these clusters were isolated both in Chile and Bolivia, suggesting a significant circulation of invertebrate and/or vertebrate hosts of T. cruzi between these 2 countries. Low clonal variability in Peru suggested the occurrence of a 'founder effect' in this country. The potential usefulness of a cladistic approach in epidemiology is discussed.