Fellows

Eliza Little, MESc

2010 TRI Fellow in Puerto Rico
 

Habitat segregation of Aedes aegypti and Aedes mediovittatus within heterogeneous urban areas in Patillas, Puerto Rico, using high-resolution satellite data

Aedes aegypti is an important dengue vector worldwide because of its association with humans in urbanized areas. Vector control methods have focused on eliminating artificial water containers that function as breeding sites. The efficacy of this method may be undermined by the presence of alternative natural container breeding species. Ae. mediovittatus, a mosquito species native to Puerto Rico, is competent with a high rate of vertical transmission in laboratory tests. Its distribution may overlap with Ae. aegypti in areas with low-density housing and the presence of trees.

The goal is to determine whether dengue vectors segregate within heterogeneous urban areas in Puerto Rico, using high-resolution satellite data and geospatial analytical tools.

Classification of land cover in the study site was conducted using a WorldView2 satellite image acquired March 25th, 2010. In total, seven urban areas were analyzed, six classes were defined; and ground data were collected and used to train and test maximum likelihood classifications. The overall accuracy ranged from 80-99% with associated kappa coefficients 0.73-0.9.

BG-Sentinel traps were used to collect adult mosquitoes over a 12-week period. At a radius of 100 m from each BG-trap, the percent cover of trees and housing density were calculated, normalized, and included in a multinomial logistic regression comparing presence of either species or co-occurrence to the presence of neither species.

Preliminary analysis suggests that Ae. mediovittatus and Ae. aegypti segregate within urban areas, with Ae. mediovittatus being more abundant in more forested areas. Very high-resolution data from a newly launched satellite allows discrimination of heterogeneous urban habitats with a level of detail not possible with previous imagery.  Using geospatial analytical tools to define environmental features linked to the distribution of these vectors will allow public health agencies to focus intervention efforts on areas of high risk.

Publication

Characterizing the Urban Environment of Dengue Mosquitoes in Patillas, Puerto Rico