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Trypanosoma cruzi can cause both acute disease and a more chronic cardiomyopathy. To find out whether trypanocidal therapy kills the parasite or improves outcomes in chronic disease, researchers randomized 2854 patients with chronic Chagas cardiomyopathy to benznidazole or placebo for up to 80 days.
Polymerase-chain-reaction assays were used to document subjects' serostatus for the parasite, which was present in 61% of participants at baseline. By the end of treatment, conversion to seronegative status occurred in 66% of patients receiving benznidazole and 34% of those receiving placebo, a significant difference that continued at ≥5 years of follow-up. However, the two groups showed no significant differences in the combined primary outcome of adverse events or its components, including death, significant arrhythmia, new or worsening heart failure, embolic events, or cardiac transplantation.
Morillo CA et al. Randomized trial of benznidazole for chronic Chagas' cardiomyopathy. N Engl J Med 2015 Sep 1; [e-pub]. (http://dx.doi.org/10.1056/NEJMoa1507574)
Comment
In this well-conducted randomized trial, trypanocidal therapy improved seroconversion but did not improve clinical outcomes, at least in chronic disease. The authors note that autoimmune damage has been postulated as an important component of late disease and that their results do not necessarily apply to earlier phases of the disease. Interestingly, rates of seroconversion varied by geographic area, which may be a proxy for the various genetic subtypes of T. cruzi.