We have collated and mapped reports of the dhps K540E mutation in Africa. The mutation is a marker of resistance to SP (Fansidar) and has a remarkable geographical distribution.
Check the interactive map http://www.drugresistancemaps.org/maps/dhps540/ to see the distribution and check that your study has been included.
Inbarani Naidoo and Cally Roper
Following the path of most resistance: dhps K540E dispersal in African Plasmodium falciparum. Trends in Parasitology, 26(9):447-456.