Biological and isoenzymatic characterization of Trypanosoma cruzi strains isolated from sylvatic reservoirs and vectors from the state of Santa Catarina, Southern Brazil.

Sixty eight Trypanosoma cruzi strains were isolated in the state of Santa Catarina, Southern Brazil, from sylvatic reservoirs or naturally infected vectors and characterized by their biological behaviour in mice, morphology of bloodstream forms and isoenzyme profiles. Twenty eight strains were isolated from the triatomine bug (Panstrongylus megistus), 2 from rodents (Echimys dasythrix and Akodon sp) and 38 from opossums (Didelphis marsupialis). The infectivity in mice of 48 T. cruzi strains showed that 2 (4.2%) were of high virulence, 19 (39.6%) of medium virulence, 15 (31.2%) of low virulence and 12 (25.0%) produced subpatent parasitemia in mice. A morphological study of bloodstream trypomastigotes from 8 T. cruzi strains showed a predominance of stout forms. The isoenzyme pattern of 59 T. cruzi strains showed that 54 (91.5%) belonged to zymodeme Z1, 3 (5.1%) to zymodeme Z2 and 2 (3.4%) to mixed zymodemes, Z1 and Z2. All 34 T. cruzi strains analyzed from opossums were Z1. Three out of 5 strains isolated from adults of P. megistus collected inside houses, belonged to zymodeme Z2 and two strains exhibited mixed zymodemes, Z1 and Z2, in 5 out of 6 enzymes studied. Although the State of Santa Catarina is a non endemic region for human Chagas'disease, the presence of zymodeme Z2 parasites in the sylvatic vector, P. megistus, captured in domiciliary environments suggests the possibility of human and/or domestic mammal infection by T. cruzi.