Designing a multidimensional vulnerability index for supervising dengue cases from 2015 to 2020 in a low/middle-income country: A spatial principal component analysis

Background: Dengue is one of the most prevalent infectious diseases worldwide, affecting around 390 million people each year. Previous studies have reported that social, climatic, and government-related conditions can increase the frequency of dengue events in some territories. This study aimed to design a multidimensional vulnerability index encompassing social, climatic, and government-related factors associated with dengue and correlate this index with dengue incidence in Colombia between 2015 and 2020. Methods: Observational, ecological, longitudinal study conducted from 2015 to 2020. Based on administrative data from state sources such as the Ministry of Health, the National Administrative Department of Statistics (DANE), the National Planning Department (DNP), and other sources, a principal component analysis was performed to design the multidimensional vulnerability index. Results: Data from 1099 municipalities over the six-year analysis period were included. The index comprised five main factors: climatic factors, basic service coverage, precipitation-related factors, municipal performance, and transparency in social development. The proposed index showed a mean vulnerability of 0.48 (median = 0.48; SD = 0.15; IQR: 0.36-0.59). Higher index values were found in the southwestern territories and the Amazon regions of Colombia, as well as some municipalities in the Caribbean region. These territories exhibited the highest levels of poverty, regional access to services, precipitation, and temperature. Spatial analyses confirmed this concordance. The nonlinear association between the MVI and dengue incidence suggests threshold effects, in which municipalities with MVI scores above 0.8 have higher levels of dengue morbidity. Conclusions: The proposed index showed a suitable correlation with dengue case frequency at a regional level and could be extended to other countries for the development of dengue outbreak prevention campaigns. Author summary: Dengue is a mosquito-borne viral disease causing millions of infections each year, with significant health impacts in low- and middle-income countries. Vulnerability to dengue increases in settings with poor access to basic services, poverty, under-resourced public health, and limited capacity of institutions to prevent and respond to disease outbreaks. Moreover, environmental factors like high temperatures and rainfall create habitats favoring the growth of mosquitoes that transmit the disease. In this study, the authors designed a Multidimensional Vulnerability Index to measure how these combinations of climatic, social, and governance-related factors influence the risk of dengue outbreaks. Using data from over 1,000 Colombian municipalities between 2015 and 2020, the authors found that areas with higher index scores, especially in the Amazon, Pacific, and Caribbean regions, had higher numbers of reported dengue cases. As climate change raises global temperatures and expands the habitats of dengue-carrying mosquitoes, dengue may emerge in countries and regions where it was not previously a public health concern. The proposed index may serve as a valuable tool for identifying high-risk areas and supporting targeted prevention strategies. While developed in the Colombian context, the framework can be adapted to other countries facing challenges of infectious disease risk and social vulnerability.