Effectiveness of benznidazole in the treatment of Chagas disease in children and adults: a long-term retrospective cohort study.

Chagas disease, caused by Trypanosoma cruzi, is endemic to the Americas but has spread worldwide due to migration. Benznidazole is effective, but long-term follow-up efficacy studies are scarce and include only small numbers of patients. We analyzed data from a retrospective cohort of Chagas disease patients treated with benznidazole at a large tertiary center in Argentina (1980-2019). Treatment response was assessed through clinical, parasitological, and serological follow-up. Parasitemia was evaluated by direct visualization or PCR. Among 567 treated patients, 464 met selection criteria, including 411 children (median age: 46 months, IQR: 9.5-124 months) and 53 adults (median age: 26 years, IQR: 20-34 years). At diagnosis, 11/411 (2.68%) children and 1/53 (1.9%) adults were symptomatic; all improved after treatment. Baseline parasitemia was detected in 289/445 (64.94%) of patients, and 279/289 (96.54%) had parasitological follow-up for at least 3 years. Median benznidazole dose was 6.6 mg/kg/day in children and 5.6 mg/kg/day in adults, with treatment durations of 8 weeks and 31 days, respectively. All patients cleared parasitemia at treatment completion. Median serological follow-up was 4.8 years for children and 2.8 years for adults. At 1-year follow-up, 38.8% of patients showed >20% reduction in T. cruzi antibody titers, and 29.8% achieved seronegativity, with younger patients converting faster (P < 0.01). In this Argentinian cohort, Benznidazole achieved sustained parasitemia clearance and declining antibody titers, supporting early treatment initiation.