Differentiation of newly isolated strains of Trypanosoma (Schizotrypanum) cruzi by agglutination and precipitation reactions.

Serological relationships between new isolates of Trypanosoma cruzi from a single locality have been examined by direct agglutination and immunodiffusion, and compared with established strains. The strains were divided into three groups according to the absorption properties of their precipitinogens. The three groups were defined by the same characteristics as those in which strains of wide-ranging provenance and long laboratory history have been placed by previous workers. A lack of correspondence between the antigenic constitutions of the groups as described here and as described previously was demonstrated using reference strains. Relatedness values were calculated from agglutination titres, which indicated a complex heterogeneity of antigens, and from which a scheme of relationships was drawn.