Development of an Integrated Surveillance System to Improve Preparedness for Arbovirus Outbreaks in a Dengue Endemic Setting: Descriptive Study

Abstract

Background: Dengue fever, transmitted by Aedes aegypti and Aedes albopictus mosquitoes, poses a significant public health challenge in tropical and subtropical regions. Dengue surveillance involves monitoring the incidence, distribution, and trends of infections through systematic data collection, analysis, interpretation, and dissemination. It supports public health decision-making, guiding interventions like vector control, vaccination campaigns, and public education.

Objective: Herein, we report the development of a surveillance system already in use to support public health managers against dengue transmission in Foz do Iguaçu, a dengue-endemic Brazilian city located in the Triple Border with Argentina and Paraguay.

Methods: We present data encompassing the fieldwork organization of more than 100 health agents; epidemiological and entomological data were gathered from November 2022 to April 2024, totalizing 18 months of data collection.

Results: By registering health agents, we were able to provide support for those facing issues to fill their daily milestone of inspecting 16 traps per working day. We filtered dengue transmission in the city by patient age, gender, and reporting units, as well as according to dengue virus serotype. The entomological indices presented a strong seasonal pattern, as expected. Several longtime established routines in Foz do Iguaçu have been directly impacted by the adoption of Vigilância Integrada com Tecnologia (VITEC).

Conclusions: The implementation of VITEC has enabled more efficient and accurate diagnostics of local transmission risk, leading to a better understanding of operational activity patterns and risks. Lately, local public health managers can easily identify hot spots of dengue transmission and optimize interventions toward those highly sensitive areas.

Keywords: Aedes aegypti; dengue fever; surveillance; transmission risk; vector control.

Figure 1.. Routine of field surveillance in the city of Foz do Iguaçu. (A) The app home screen showing the interactive menu; (B) screen to inform data for Adultrap installment in the field; (C) cataloging 1 house to receive 1 Adultrap; and (D) reading the QR code during weekly trap inspection.

Figure 2.. Epidemiological dashboard showing the notification and confirmation of dengue cases in 2023 by sex, age, serotype, and the screening technique used. The panel is composed of figures extracted from VITEC. VITEC: Vigilância Integrada com Tecnologia.

Figure 3.. Epidemiological dashboard from Foz do Iguaçu. (A) The historical temporal series of DENV notifications In Foz do Iguaçu since VITEC was developed. (B) Dengue notifications per year. The panel is composed of figures extracted from VITEC. DENV: dengue virus; VITEC: Vigilância Integrada com Tecnologia.

Figure 4.. Entomological indices obtained from Foz do Iguaçu during November 2022 to April 2024. (A) TPI: the percentage of positive Adultraps; (B) ADI: average number of adult Aedes aegypti per Adultrap; (C) OPI: the percentage of positive ovitraps; and (D) EDI: average number of eggs per ovitrap. ADI: Adult Density Index; EDI: Egg Density Index; OPI: Ovitrap Positivity Index; TPI: Trap Positivity Index.

Figure 5.. Dengue transmission risk maps for Foz do Iguaçu in the two first epidemiological weeks of 2023. (A) Heat map (kernel density estimation) showing the areas of Foz do Iguaçu with higher concentrations of dengue reports. (B) Choropleth map respecting the city subdivision in 12 areas of 8000‐12,000 dwellings each. The panel is composed of figures extracted from VITEC. VITEC: Vigilância Integrada com Tecnologia.