Sera from 452 patients and blood donors were tested for antibodies to Tryp-anosoma cruzi. The complement fixation test and a counterelectrophoresis test were used. The results showed that both tests agreed in 92% of the sera. However, the counterelectrophoresis test was not as sensitive as the complement fixation test.

The immunodiffusion and complement fixation tests for histoplasmosis were compared on 2,090 initial sera from 70 proven cases of histoplasmosis, 177 routine chest hospital patients, and 1,843 coal miners from outside the major endemic area for histoplasmosis. The complement fixation test using histoplasmin as antigen detected antibodies in the sera of 72.8% of the 70 proven cases, while the com...