Usefulness of PCR for monitoring benznidazole response in patients with chronic Chagas' disease: a prospective study in a non-disease-endemic country.

OBJECTIVES: This prospective study focused on the evaluation of antiparasitic therapy in chronic Chagas' disease, monitored by PCR.

PATIENTS AND METHODS: One hundred and eighty-one patients, all seropositive for Trypanosoma cruzi infection, underwent specific chemotherapy with benznidazole. Twelve patients were classified as young (2-19 years), 122 patients were classified as adults (20-39 years) and 47 patients were classified as seniors (>or=40 years). In total, 116 (64%) were asymptomatic and 65 (36%) were symptomatic. Patients were monitored for 90, 150 and 420 days after treatment by PCR and serology.

RESULTS: Before treatment, 68% had a positive PCR result. PCR positivity was significantly more frequent in patients aged 2-19 years (P = 0.0007) and in short-term immigrants (P = 0.0076). No differences in PCR sensitivity were observed between samples of patients with chronic symptomatic or indeterminate Chagas' disease. All patients presented an early conversion of PCR results 90 days post-treatment. However, at the end of the follow-up period PCR had become positive in four patients (4 out of 58 patients; 6.9%) who had strictly adhered to the treatment and in one who did not complete the treatment. Only one patient showed an alternating PCR during follow-up.

CONCLUSIONS: We conclude that PCR is a useful tool for the early detection of parasite susceptibility to benznidazole and for the post-treatment parasitological follow-up of patients with chronic Chagas' disease.