Identification of Risk Determinants of Dengue Transmission Through Landscape Analysis

Overview

This retrospective observational study aims to determine the probability of the risk of dengue transmission through a model based on epidemiological, entomological, socioeconomic, demographic, and landscape variables in the El Vergel neighborhood in the municipality of Tapachula, Chiapas, Mexico. The main question it aims to answer is: 1\. Is it possible to identify the risk determinants of dengue transmission by developing a probabilistic model based on the landscape analysis of epidemiological, entomological, sociodemographic, and landscape variables in an endemic urban area of the municipality of Tapachula, Chiapas, Mexico? Participants will be selected from a registry obtained from the Secretary of Health of cases of dengue fever, which will be contrasted with the entomological, socioeconomic, demographic, and landscape variables in the El Vergel neighborhood in Tapachula, Chiapas, Mexico. They will be not contacted or sampled for biologic testing in any shape or form, only the data already collected from the health services will be used.

Identification of the risk determinants of dengue transmission through landscape analysis in the "El Vergel" neighborhood, Tapachula, Chiapas, Mexico Dengue is a disease transmitted mainly by the Ae. aegypti present in our region, despite vector surveillance and control activities, the circulation of the virus is constant and new strategies are required that contribute to reducing the incidence of the disease, which can be fatal. On the other hand, drones are tools already used in precision and security agriculture, among others; by means of them, it is possible to obtain high-resolution images of large areas of land. This work will use these images in combination with epidemiological, entomological, socioeconomic, and demographic data to identify the risk factors for dengue transmission in an urban area of the city of Tapachula and will generate a model that will allow defining the risk areas in the area. study. Objective: To determine the probability of the risk of dengue transmission through a model based on epidemiological, entomological, socioeconomic, demographic, and landscape variables in the El Vergel neighborhood in the municipality of Tapachula, Chiapas. Material and methods: Information from entomological, housing condition, and sociodemographic surveys of the El Vergel neighborhood, Tapachula, Chiapas, obtained during the period from November to December 2019, will be used. In addition to epidemiological information on the incidence of dengue and the placement of ovitraps in the study area during the sampling period, six months before and six months after. Specialized cartography will be used, made from fine-scale aerial photographs taken at a height of 100m by a multirotor drone with six DJI Matrice 600 model rotors with two types of cameras, a Zenmuse X5 model that captures images in the visible spectrum at 16 MP and a multispectral camera with five spectral bands MicaSense RedEdge -MX with RGB sensor with a spatial resolution of 5 cm per pixel. The images were taken simultaneously with the entomological, socioeconomic, and demographic surveys. Georeferenced orthophoto cartographic maps, digital surface models, digital terrain models, and specialized cartography of vegetation indices will be used: Normalized Difference Vegetation Index (NDVI), Difference Vegetation Index Green Normalized (GNDVI), RedEdge Normalized Difference Vegetation Index (NDVIRe) and Chlorophyll Index (CIGreen), height and diameter of the trees present in the study area, to take various variables related to the landscape (environmental variables). The data analysis will be based on a mathematical model based on the principle of partial least squares, to determine the spatial association between the epidemiological indicators (number and georeferencing of cases), entomological (immature and adult stages of Ae. aegypti), condition index housing, sociodemographic and landscape data. Period: 6 months Type of study: Cross-sectional, retrospective, observational. Selection criteria: The construction of databases will consider the houses of Colonia El Vergel, Tapachula, Chiapas, where its inhabitants of legal age, accepted through informed consent to participate in the surveys and collection of entomological and sociodemographic data in situ and aerial photographs at a height of 100m away. Homes that do not have residents will be grounds for exclusion, and those in which the participants do not allow the collection of complete information will be eliminated. Sample size and sampling: A multi-stage stratified sampling will be used to select dwellings. The sample size will be obtained according to the sample formula for proportions, which was calculated in n=196 dwellings. Results: A probabilistic risk model will be generated based on the variables of different natures used and maps will be built to identify the areas of greatest risk for dengue transmission in the study area. Conclusion: Generate scientific evidence that allows maximum use of these advances for the benefit of populations. The determination of risk areas using specialized cartography carried out using high-resolution aerial photography using drones, has already been demonstrated and recently published.