Comparison of counterimmunoelectrophoresis (CIE) with other serologic tests in the detection of antibodies to Trypanosoma cruzi.

Application of counterimmunoelectrophoresis (CIE) in detection of antibodies against Trypanosoma cruzi in sera of 180 subjects from an endemic area (Bolivia), and 50 subjects from a nonendemic area (U.S.A.) was carried out, and the results were compared to ones obtained with latex agglutination (LA) and indirect hemagglutination (IHA). The optimal conditions for CIE were determined to be as follows: barbitone buffer of pH 8.2 and ionic strength 0.05 M was used in the chambers and in preparing the 1% agarose plates. The wells in the plates were 5 mm in diameter and 3 mm apart. Electric current was applied at 500 volts and 25 mA for 60 minutes. T. cruzi antigen (Center for Disease Control) was used in a dilution of 1:2. The sera were studied undiluted. The study population comprised the following groups: LA+ IHA+ (group I); LA+ IHA- (group II); LA- IHA+ (group III); LA- IHA- (group IV); and the control group (group V). Each group was comprised of 50 sera, except for group II which was comprised of only 30 sera. Antibodies were detected by CIE in 94% of sera in group I, 40% in group II, 76% in group III and 6% in group IV. There were no positive reactions in group V. CIE was positive in 74% of sera from the combined LA+ serum groups (I and II), and in 85% of sera from the IHA+ groups (I and III). A good correlation between CIE and the other tests in the LA+ and IHA+ group (I), and the lack of false positive reactions in group V suggest that CIE is a good diagnostic method for detection of T. cruzi antibodies. However, this study showed that IHA is a more sensitive test in epidemiological surveys than CIE. The finding of 6% sera positive by CIE in group IV may indicate a lower specificity of the test.