Aedes aegypti in the city of Córdoba: spatial distribution and habitat suitability drivers

Background

According to the World Health Organization, dengue is among the top ten global health threats. The invasion of new sites by Aedes aegypti and their permanence depends on environmental characteristics of the site. Therefore, the objective was to understand the environmental characteristics that affect Ae. aegypti distribution in Córdoba city, Argentina.

Methods

This evaluation was carried out through species distribution models, using maximum entropy modeling technique, incorporating a set of environmental variables known to influence the presence and suitability of Ae. aegypti habitats. The factors evaluated included both meteorological variables, such as minimum and maximum temperature and average precipitation, land cover characteristics like vegetation index and built-up index, and population count. Temperature and precipitation conditions constrain the development and survival of the vector. Vegetation can act as a temperature regulator and provide resting sites, while populated and built-up areas relate to the availability of breeding sites and blood sources.

Results

The results indicate that Ae. aegypti habitat suitability is determined by human population count (permutation importance: 89 in 2015, 80.9 in 2017), the amount of built-up areas (61.7, 80.8), vegetation greenness (70.7, 55.9), and minimum temperature (42.2, 92.6). Human population manifested a positive effect on the habitat suitability as well as minimum temperature, while vegetation and the amount of built-up areas showed a quadratic relationship.

Discussion

In this study, we incorporate temperature and precipitation as spatial variables, which were not considered in similar studies in Córdoba City. Our study's results highlight that although demographic and land cover variables prevailed in importance, meteorological variables are also good predictors of spatial distribution of Ae. aegypti at the local scale.

Conclusions

The importance of generating maps and/or models to identify the distribution of mosquito habitats lies in the fact that they can show vulnerable areas and guide stakeholders efforts on public health prevention. Also, they can direct actions to vector control and, consequently, the pathogens they transmit.