Dengue serotype dynamics in northeastern Peru: A study from the Amazonas region, 2021-2025

In Peru, more than 270,000 dengue cases were reported nationwide in 2024, with 261 deaths, surpassing historical figures in various regions. The Amazonas region, located in northeastern Peru and home to an estimated 426,806 inhabitants, reported 1517 dengue cases in 2024. As of 2025, 1582 cases and 7 dengue-related deaths have already been reported. Dengue virus (DENV) serotype circulation patterns influence outbreak dynamics and disease severity. This study aimed to describe the spatiotemporal distribution of DENV serotypes and analyze their relationship with clinical and epidemiological characteristics in the Amazonas region of Peru from 2021 to 2025.

An observational, retrospective, and analytical study was conducted using a clinical-epidemiological database of confirmed dengue cases reported between 2021 and 2025. Serotype distribution was analyzed using geographic mapping and time series. Associations between serotypes and clinical classification, incidence, and outbreak magnitude were assessed using ANOVA, chi-square, and logistic regression.

A significantly heterogeneous distribution of DENV serotypes was observed across provinces (p < 0.001). DENV-2 was the most prevalent serotype and was predominantly associated with large-scale outbreaks. DENV-1 and DENV-3 circulated less frequently. No significant association was found between serotype and clinical classification or overall incidence. However, prior dengue infection (based on clinical-epidemiological records that included self-report) was significantly associated with a reduced likelihood of developing warning signs (p = 0.032) CONCLUSIONS: Between 2021 and 2025, the Amazonas region exhibited a spatiotemporally varied pattern of DENV serotype circulation, with DENV-2 as the dominant serotype linked to major outbreaks. While serotypes were not directly associated with clinical severity, previous infection (based on clinical-epidemiological records that included self-report) conferred partial protection against severe manifestations. These findings underscore the importance of continuous serotype surveillance to inform public health interventions.