Table 4
SEROLOGICAL METHODS FOR DIAGNOSIS OF CHAGAS AND ANTIGENS USED
(WHO 1991:40)
| Complement‑fixation test (CFT). Aqueous or methanol extracts of whole T. cruzi have been widely used but have been replaced by purified fractions of the parasite in an attempt to standardize the sensitivity and specificity measures. |
| Indirect immunofluorescent antibody test (IFAT). Formol‑fixed epimastigotes are stable antigens. The IFAT has the advantage that it can be used for differentiating IgM from IgG antibodies. |
| Indirect haemagglutination test (IHA). The antigens are polysaccharide or glycoprotein fractions from epimastigotes. Red cells sensitized with those antigens can be stored lyophilized or in suspension. |
| Direct agglutination test (DA and 2‑MEDA). The antigen consists of whole epimastigotes treated with trypsin, and fixed with formaldehyde and filtered to prevent autoagglutination. The test can be used for detection of IgG or IgM antibodies. |
| ELISA. The antigen consists of peroxidase, or phosphatase‑labeled conjugates or fractions of T. cruzi adsorbed to polyvinyl plates or other materials, and is stable. The test can be used for detection of IgG or IgM antibodies. |
| Latex agglutination. Polystyrene particles absorbed with T. cruzi extracts are used. |
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