Comparison of four serological tests for the diagnosis of Chagas disease in a Colombian endemic area

Abstract

The performance of 4 serological tests for the diagnosis of Chagas disease was evaluated in Santander, Colombia, a region still presenting active transmission. Serum samples from 638 individuals were submitted to an enzyme immunoassay test (EIA), using total lysate of a local Trypanosoma cruzi strain and 52.5% were positive (335/638). A subset of this group (94 positive individuals and 90 seronegatives) was randomly selected for further serological confirmation. Three additional tests were used--indirect immunofluorescence (IIF) and 2 distinct enzyme-linked immunosorbent assays using total lysate of the Y strain (EIA BM) and a mixture of 2 recombinant antigens (EIA RA). Seventy-nine patients were seropositive in all tests (84.0%-79/94). The number of positive sera with the IIF, EIA RA and EIA BM was 84/94 (89.4%), 80/94 (85.1%) and 79/94 (84.0%), respectively. In 15 out of the 94 EIA seropositive patients (16.0%), 10 individuals were negative in all 3 tests (10.6%-10/94). One was negative in the EIA BM and positive in the other two tests (1.1%-1/94) and 4 patients were positive, solely, in the IIF assay (4.3%-4/94). Relative to the 90 EIA negative individuals, 89 were confirmed in all other tests (98.9%-89/90). One individual, although seronegative in the IIF, was positive in both confirmatory EIA tests (1.1%-1/90). In addition, 120 blood specimens were submitted to PCR amplification. This group consisted of 79 confirmed seropositive cases, 16 individuals with discordant serological results and 25 validated seronegative individuals. The PCR was able to detect the presence of parasite DNA in 67 out of the 79 seropositive patients (84.8%), in 8 individuals with discordant serology (50.0%) and in only one seronegative individual (4.0%). The results pointed to the necessity for performing more than one serological test, preferentially with antigens from autochthonous strains, to achieve a reliable diagnosis of Chagas disease in Colombia.

Efficacy of benznidazol treatment for asymptomatic chagasic patients from state of Rio Grande do Sul evaluated during a three years follow-up

“…This fact must be considered when low or borderline antibody titers are found since most of the commercial kits use the T. cruzi TcII lineage as the antigen. Gutierrez et al (2004) compared four different serological tests and reported discordant results for 15 out of 94 sera from Colombian chagasic patients. According to the authors, an in-house ELISA using an autochthonous T. cruzi TcI as the antigen shows the highest sensitivity, probably due to the fact that the TcI genotype is the most prevalent in that region.…”

Anti-Trypanosoma cruzi antibody detection in blood donors in the Southern Brazil

“…If one does not take into account cost, reorganization of blood center routine and preoccupation with other infectious agents, many studies defend the use of more than one technique for a safe serological triage in blood centers [18,[25][26][27][28].…”

Evaluación preliminar de la prueba comercial “Chagas (Trypanosoma cruzi) IgG-ELISA®” en individuos colombianos

“…Si bien en Colombia se han empleado distintas pruebas de ELISA (29)(30)(31)(32)(33)(34)(35), estas, por lo general, incluyen lisados proteicos de cepas pertenecientes a la DTU I, pues es la DTU de mayor circulación en el país (35). Sin embargo, en nuestro medio existen reportes del hallazgo en pacientes chagásicos de las DTU II, III, IV y VI (35)(36)(37)(38)(39)(40)(41).…”