Over 14 years of national surveillance in the Dominican Republic, leptospirosis killed 8.5% of 5,412 reported cases — a rate that remained stubbornly flat with no significant downward trend. Male sex carried an independent 79% higher mortality odds (OR 1.79), comorbidities raised odds by 76%, and clinical complications — the strongest single predictor — tripled death risk (OR 3.16). Case fatality varied dramatically by province, ranging from 2.4% to over 22%, with lower-incidence provinces paradoxically showing higher death rates, hinting at diagnostic underrecognition in less-exposed regions.
These findings matter beyond the Caribbean. Leptospirosis is the world's most widespread zoonotic infection, yet it remains chronically neglected despite killing tens of thousands annually. The 8.5% CFR reported here substantially exceeds the 5–10% threshold often cited for well-managed endemic settings and mirrors outcomes from resource-limited contexts where diagnosis arrives too late. The gender effect partially mediating through complications suggests occupational exposure drives later, more severe presentation rather than intrinsic biological vulnerability — a modifiable risk. The absence of improvement over 14 years is the most alarming signal: unlike infectious diseases with declining mortality, leptospirosis fatality in the DR appears structurally entrenched. As climate change intensifies flooding across the Caribbean — a primary transmission driver — these baseline figures will worsen without targeted intervention. This is a preprint not yet peer-reviewed; the surveillance data quality and case ascertainment completeness warrant scrutiny before conclusions are finalized.