[Comparison of a PCR test based on the histone H2A/SIRE genes with classical serological tests for the diagnosis of chronic Chagas disease in Colombian patients].
BACKGROUND
Diagnosis of Chagas disease in its latent and chronic phase is difficult because of the low parasitemia levels. Therefore, serological and molecular techniques are necessary to achieve an appropriate diagnosis.


OBJECTIVE
The polymerase chain reaction based on the amplification of the SIRE element inserted into H2A encoding genes was compared with classical serological tests for the diagnosis of Chagas disease in Colombian patients.


METHODS
An agreement study was carried out by comparing the PCR with ELISA (enzyme linked immuno sorbent assay) and IFAT (indirect immunofluorescence) tests. In addition, the PCR sensitivity and specificity were determined. A sample of 156 individuals was tested with the H2A PCR primers after a Chagas disease classification based on clinical, epidemiological and serological data associated with each patient. In addition, 97 out of 156 samples were also compared with the S35/S36 PCR primers.


RESULTS
Eighty-nine of 156 samples (57%) were positive by both IFAT and ELISA and 84 (53.8%) presented the expected 234 bp amplification fragment. The sensitivity of the TcH2AF/ R PCR was 88% (95% C.I.: 75%--95%) and its specificity 92.5% (95% C.I.: 87.7%--97.2%). The kappa index for concordance between serological tests and TcH2AF/R PCR was 0.8 (95% C.I.: 73%--86%), and between the TcH2AF/R and S35/S36 PCR primers was 0.9 (95% C.I.: 84%-96%). These indices indicated a "good" and "almost perfect" agreement, respectively.


CONCLUSIONS
The TcH2AF/R PCR is a promising diagnostic tool for the detection of T. cruzi and is suggested as a tool complementary to the classical serological tests.
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D014355:Chagas Disease / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology; D003105:Colombia / Q000453:epidemiology; D016054:DNA, Protozoan / Q000032:analysis; D006657:Histones / Q000235:genetics*; D006801:Humans; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D015800:Protozoan Proteins / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D014349:Trypanosoma cruzi / Q000235:genetics* / Q000378:metabolism
D016054:DNA, Protozoan; D006657:Histones; D015800:Protozoan Proteins
Comparación de una prueba de PCR basada en los genes codificantes para la histona H2A/SIRE con pruebas serológicas convencionales para el diagnóstico de la enfermedad de Chagas crónica en pacientes colombianos.