Detecção do DNA do Trypanosoma cruzi pela reação em cadeia da polimerase (PCR) em pacientes chagasicos cronicos

AUTOR(ES)

Glaucia Elisete Barbosa Marcon

DATA DE PUBLICAÇÃO

2001

RESUMO

Chagas disease, caused by Trypanosoma cruzi, is an important endemic illness in Latin America, where an estimated 16 to 18 million persons are chronically infected. The trypanosomiasis involves a characteristic acute phase with high levels of parasites in the bloodstream, allowing a diagnosis by parasitological methods, and a chronic phase in which parasites are not detectable in blood smears, makingthe diagnosis difficult at this stage. Serological tests for T. cruzi detection in blood are sensitive, but their specificity is generally unsatisfactory. On the other hand, direct detection of parasites in blood, either by xenodiagnosis or hemoculture, is highly specific but of low sensitivity. Molecular assays such as the Polymerase Chain Reaction (PCR), which amplify certain repetitive sequences of trypanosome kinetoplast DNA (kDNA), and DNA nuclear have been proposed as good altemative tools for detection of T. cruzi in human blood. The present study aimed to test PCR diagnosis in chagasic chronic patients and doubtful serological patients attended in GEDoCh (Grupo de Estudos em Doença de Chagas)/UNICAMP. The DNA prepared ITompatient s blood was amplified by the PCR using primers of the kinetoplast minicircles and DNA nuclear. A 330 bp and 149 bp Tagmentsoriginating ITomkinetoplast DNA and DNA nuclear was specifically detected in chronic chagasic. The results of these tests were compared with serological diagnosis performed using standard techniques and xenodiagnosis. We found that seven of the serologically negative individuaIs don t give specific amplification product, whereas 43 out of 53 patients previously serodiagnosed as chagasic were positive using the Nested - PCR (DNA nuclear) method. In addition, twelve of twenty-eight patients with doubtful serologic results were confirmed as positive by PCR. That two was negative xenadiagnosis. Our results suggest that the Nested - PCR may be a toei complementary to serology in the diagnosis af Chagas disease, and that it is available for parasite detection in patients with chronic disease and patients with doubtful serologic

ASSUNTO(S)

chagas reação em cadeia de polimerase doença de

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