Version 1. 2. Supersedes v. 01 (21 May 2026). Brazil recorded its largest dengue epidemic in 2024. This preprint characterises the epidemic using three national surveillance systems — SINAN individual notification records, SIH hospital admission data, and InfoDengue municipal alert data — and reports indicators verified against the primary databases. Brazil notified 10, 466, 079 dengue cases in 2024 (InfoDengue, dengue-specific). SINAN confirmed 6, 016, 263 cases, including 8, 834 severe dengue and 101, 426 with warning signs, with 6, 338 deaths (crude case fatality 0. 105%). SIH recorded 154, 888 unique SUS hospital admissions under ICD-10 A90/A91, with 2, 429 in-hospital deaths, mean length of stay 3. 34 days, and R78, 272, 472 in direct SUS reimbursement. DENV-1 was dominant (68. 54% of 189, 618 DENV-positive typed specimens), already down from 86. 92% in 2023, while DENV-2 rose to 30. 49%. DENV-3 re-emerged at 0. 95% of DENV-positive specimens — a genuine signal, but too small a share to have driven the 2024 epidemic. The annual mean national Rt was 1. 248; the national case-weighted Rt reached 1. 262 at peak week SE12. The epidemic affected 5, 548 municipalities. Corrections in this version relative to v. 01: the 2024 hospitalisation figure of 247, 000 was a query-scope error — a multi-year ICD-10 A90 aggregate mislabelled as a single-year figure — and is corrected to 154, 888 unique admissions; the statement that Rt peaked at 1. 248 in epidemiological week 8 conflated the annual mean with a weekly peak and was not reproducible from the InfoDengue model; the characterisation of DENV-3 re-emergence as a driver of the 2024 epidemic is withdrawn, together with the associated estimate of 50 million unexposed Brazilians born after 2008; abstract severity counts are corrected to 8, 834 and 101, 426. A conflict-of-interest declaration has been added.
Igor Eduardo (Wed,) studied this question.