Genetic structure and phylogenetic relationships of Colombian Trypanosoma cruzi populations as determined by schizodeme and isoenzyme markers

Twenty-four Trypanosoma cruzi stocks isolated from vectors and from human a nd Didelphis marsupialis hosts from highly separated sylvatic localities in Colombia were characterized by isoenzyme and schizodeme analyses. The stoc ks were collected primarily from sylvatic ecotopes representing areas of lo w, moderate, and high endemicity for Chagas' diseases in Colombia. Parasite s were characterized mainly by schizodeme analysis with the restriction enz yme Eco RI and the isoenzyme analysis was performed at 10 genetic loci. The se analyses demonstrated an agreement between the classifications based on the isoenzyme analysis and on the restriction fragment length polymorphism patterns obtained with the Colombian stocks. There is clear evidence of dem ic subdivision between the eastern (E) and western (W) stocks separated by the Andean Mountains and Magdalena River, which is likely due to the geogra phic isolation generated by these topographic features. Heterozygosity esti mates indicate that the E group could be more ancient than the W group. As was postulated in a previous study, these results are also compatible with the existence of a clonal population structure in Colombian sylvatic T. cru zi. Evidence presented here failed to demonstrate a correlation between the degree of endemy and genetic clustering. Finally, schizodeme and isoenzyma tic analyses comparing Colombian T. cruzi stocks with others from Chile con firm that Colombian isolates are genetically related to zymodeme 1 and dist ant from zymodeme 2.