Average Breteau index (B.I.) throughout the year for Phitsanulok, district-wise (base map) and according to temporal changes (rings). The base map shows the average B.I. on the basis of interpolation between the villages sampled. Spokes around the base maps indicate village locations, while the inner ring values show average index values of the sampled villages. Extending to the outside from the inner ring, the outer layers represent the index variations during March, May and July, respectively.
Sarfraz et al. BMC Public Health 2012 12:853 doi:10.1186/1471-2458-12-853