Relation between Environmental Variables and the Spatial Distribution of the Aedes aegypti Mosquito in Rural Colombia

Abstract

Background: Changes in global and local environmental variables condition the distribution and density of disease vectors. This study aimed to estimate the relationship between the entomological indicator of immature and adult forms of the Aedes aegypti mosquito per unit area, the environmental variables of temperature, precipitation, and relative humidity in rural areas of two municipalities in Colombia. Methods: Four spatial regression models were fitted: The Spatial Autoregressive Model with Autoregressive Disturbances of order [1,1] (SARAR[1,1]), Spatial Error Model (SEM), Spatial Lag Model (SLM), and the Pure Spatial Autoregressive Model. Immature and adult A. aegypti forms were collected in homes during June 2013 (dry season). The houses were chosen at random and were georeferenced. Climate information was obtained from the Institute of Hydrology, Meteorology and Environmental Studies (IDEAM- Instituto de Hidrología, Meteorología y Estudios Ambientales). Climatic information was completed with mathematical interpolation from the Akima library. Results: The most appropriate model was SARAR[1,1], as it showed the lowest values of the Akaike information criterion (AIC = 473.34). In this model, the variable that best explained the entomological indicator (immature and adult forms per unit area) was the altitude of the houses in the rural area where the entomological samples were collected. This means that the higher the altitude, the lower the entomological indicator calculated. The ranges of the environmental variables in which the presence of the mosquito occurred are between 602 to 1414 m.a.s.l (meters above sea level) for altitude, 17 °C to 27 °C for temperature, 27 mm to 86 mm for precipitation, and 70% to 85% for relative humidity. Conclusions: The importance of understanding the relationship between local environmental characteristics and the presence of the vector for designing comprehensive management strategies was highlighted, contributing to better surveillance, prevention, and control of vectors and diseases transmitted by them.

Keywords

• spatial analysis
• disease vectors
• public health
• environmental variables