Evaluación de una técnica molecular para el diagnóstico de infección perinatal por Trypanosoma cruzi

Abstract

Vertical transmission of Trypanosoma cruzi (T. cruzi) infection accounts for an increasing proportion of new Chagas disease cases. Direct methods from blood samples (micromethod) are used for the diagnosis of vertically transmitted Chagas infection. Nevertheless, molecular methods are more sensitive than the aforementioned techniques and allow parasite load quantification. This study aimed to evaluate the real-time PCR method (qPCR) for the detection of T. cruzi DNA in blood samples from children born to chronically infected mothers. 

Samples of patients from different public hospitals in the Province of Córdoba were processed. Four successive blood samples were obtained from each patient at different stages: the first and the second one were taken at birth and 30-45 days later, respectively, and both were examined by micromethod and qPCR. The third sample was collected at 6-7 months and analyzed by qPCR and serological test; and the fourth specimen at 10-18 months, and was analyzed by serology testing. Blood samples were treated with Guanidine-EDTA, and automated nucleic acid extraction and qPCR with a commercial kit were performed.

Between May 2021 to May 2022, 72 patients were included, and a total of 111 samples were analyzed. Out of the total, 6 were positive by qPCR, and one of them was also positive by the micromethod. Regarding the direct diagnosis method, the sensitivity and specificity for qPCR were 100,0% and 95,5%, respectively. Moreover, nineteen third samples were studied until July 2022; one resulted positive by qPCR and serology test. In 10 samples with negative results by serology test, perinatal infection was discarded after 10 months. These results were consistent with the qPCR ones. The positive samples belonged to 4 patients: one, whose sample taken at birth was positive by both, micromethod and qPCR, and the other 3 patients were only positive by qPCR in the first, second and third samples. 

Molecular methods are more efficient than conventional techniques for the detection of T. cruzi, which is key to an early diagnosis of perinatal infection. These results will allow us to propose a new diagnostic algorithm and will avoid the underdiagnosis of patients with possible acute perinatal infection.