A 30-day once-daily benznidazole course for chronic Chagas disease

Design

Phase 2b, randomised, open-label, non-inferiority

Population

450 adults aged 18–50 with chronic T cruzi infection, Bolivia

Primary outcome

Sustained parasitological clearance to 36 months

Effect

94% vs 95% (difference −2.0, 97.5% CI −5.41 to 1.45); adverse events 37% vs 60%

TESEO, an open-label phase 2b non-inferiority trial in The Lancet Infectious Diseases, randomised 450 Bolivian adults aged 18–50 with chronic Trypanosoma cruzi infection to six regimens: standard 60-day benznidazole or nifurtimox, or shorter, longer or lower-dose alternatives.

Sustained parasitological clearance by PCR over 36 months was 95% with standard benznidazole and 94% with benznidazole 150 mg once daily for 30 days, meeting non-inferiority. Drug-related adverse events fell from 60% to 37%. All alternative regimens were non-inferior to their standard. Most adverse events began within 10–14 days whatever the duration.

Toxicity is the main reason Chagas treatment is abandoned. A shorter, once-daily course that halves the dose and cuts side effects would make completion more likely.

This is phase 2b, in one country and two parasite settings; the authors call for phase 3 trials before guidelines change. Until then, keep to the standard regimen and monitor closely in the first two weeks.

• Monitor patients on benznidazole or nifurtimox closely in the first two weeks, when most adverse events begin
• Keep to the standard regimen until phase 3 data and guidelines support the shorter course
• Screen migrants from endemic Latin American countries and their children for Chagas disease where relevant

Why it matters

Halving the treatment burden could fix Chagas disease's main failure point: patients stopping treatment.

Don't overread it

Phase 2b and PCR clearance, not clinical outcomes; it is not yet a guideline regimen.

The statistics, in plain English

Non-inferiority means the new regimen was not worse than the standard by more than a pre-set margin of 9.5 points; the 30-day arm's difference was −2.0 points with an interval that stayed well inside that margin.

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