Trypanosoma cruzi: presence of the two major phylogenetic lineages and of several lesser discrete typing units (DTUs) in Chile and Paraguay

Multilocus enzyme electrophoresis (MLEE) of 99 Chilean and 11 Paraguayan st ocks of Trypanosoma cruzi, the agent of Chagas disease, was performed for 2 2 variable genetic loci. As previously shown for this parasite in other geo graphic areas, a pattern of long-term clonal evolution of T. cruzi genotype s was inferred, both by strong departures of Hardy-Weinberg expectations an d high linkage disequilibrium. The presence of the two major phylogenetic l ineages that subdivide the species T. cruzi [Tibayrenc, M., 1995. Populatio n genetics of parasitic protozoa and other microorganisms. In: Baker, J.R., Muller. R., Rollinson. D. (Eds.), Advances in Parasitology. vol. 36, Acade mic Press, New York, pp. 47-115: Souto, R.P., Fernandes, O., Macedo, A.M., Campbell, D.A.. Zingales, B. 1996. DNA markers define two major phylogeneti c lineages of Trypanosoma cruzi. Mel. Biochem. Parasitol. 83, 141-152] and of several lesser genetic subdivisions ('discrete typing units' or DTUs, Ti bayrenc, M., 1998a. Genetic epidemiology of parasitic protozoa and other in fectious agents: the need for an integrated approach. Int. J. Parasitol. 28 (1), 85-104; Tibayrenc, M.. 1998b. Beyond strain typing and molecular epid emiology: integrated genetic epidemiology of infectious diseases. Parasitol . Today 14, 323-329; Tibayrenc, M., 1998c. Integrated genetic epidemiology of infectious diseases: the Chagas model. Mem. Inst. Oswaldo Cruz 93 (5), 5 77-580). was recorded in this region. Comparison between clonal populations in sylvatic and domestic transmission cycles of the disease in Chile stron gly suggests that these two cycles are at least partially separated from on e another. (C) 2001 Elsevier Science B.V. All rights reserved.