Geographic expansion of dengue follows increased incidence and mortality among the elderly: an 11–year retrospective cohort study of 14 million cases in Brazil

Introduction: Dengue persists as a public health challenge in Brazil and is highly influenced by sociodemographic, environmental, and climatic conditions. The objective of this study is to describe the evolution of dengue cases, hospitalizations, and deaths in Brazil from 2014 to 2024, characterizing the clinical–epidemiological profiles and regional differences, with an emphasis on age gradients of severity. Methods: This is a real–world retrospective cohort study, with spatial and temporal ecological components. We utilized confirmed Dengue cases from Brazil’s Ministry of Health (MoH). Definitions for Dengue with Warning Signs and Severe Dengue followed MoH standards. Rates per 100,000 inhabitants (incidence, hospitalization, and mortality) were estimated by age group and region. Additionally, signs/symptoms, comorbidities, and available viral serotyping were assessed. Results: Between 2014 and 2024, a total of 14,215,369 cases were confirmed. Dengue with Warning Signs accounted for 1.5% (217,619) and Severe Dengue for 0.1% (18,331). There were 12,760 deaths (case–fatality rate: 0.1%), of which 80.1% had laboratory confirmation. There were 464,413 hospitalizations (3.3%); among those hospitalized, 10,436 progressed to death (2.25%). Women accounted for 54.1% of the cases; hypertension and diabetes mellitus were the most frequent comorbidities and were concentrated among Severe Dengue and deaths. The Southeast Region accounted for 58.6% of the cases; growth was observed in the Southern Region. Adjusted rates evidenced an age gradient: dengue incidence was highest in the 10–39 age group, but hospitalizations, Severe Dengue, and mortality increased sharply after the age of 60; this pattern was more intense in the South and Southeast regions. The most described warning sign was intense and continuous abdominal pain, present in 49.6% of cases in the 5–to–9 age group. Among those over 70 years old, postural hypotension/lipothymia was a clinical sign described as frequently as abdominal pain. Conclusions: A decade of data indicates the territorial expansion of dengue with worsening outcomes in the elderly, possibly leading to growing pressure on healthcare networks, mainly in the country’s historically naive areas. These findings support the prioritization of clinical triage based on age–related risk and comorbidities, and the need to strengthen integrated surveillance in high–risk and naïve populations.