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 Sa nta Catarina, Southern Brazil, from sylvatic reservoirs or naturally i nfected vectors and characterized by their biological behaviour in mic e, morphology of bloodstream forms and isoenzyme profiles. Twenty eigh t strains were isolated from the triatomine bug (Panstrongylus megistu s), 2 from rodents (Echimys dasythrix and Akodon sp) and 38 from oposs ums (Didelphis marsupialis). The infectivity in mice of 48 T. cruzi st rains showed that 2 (4.2%) were of high virulence, 19 (39.6%) of mediu m virulence, 15 (31.2%) of low virulence and 12 (25.0%) produced subpa tent parasitemia in mice. A morphological study of bloodstream trypoma stigotes from 8 T. cruzi strains showed a predominance of stout forms. The isoenzyme pattern of 59 T. cruzi strains showed that 54 (91.5%) b elonged 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 w ere Z1. Three out of 5 strains isolated from adults of P. megistus col lected inside houses, belonged to zymodeme 22 and two strains exhibite d mixed zymodemes, Z1 and 22, 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 22 parasites in the sylvatic vector, P. megistus, captured in domiciliary environments suggests the possib ility of human and/or domestic mammal infection by T. cruzi.