One difficulty in understanding the epidemiology of drug resistance in Cambodia is that we have little notion of what an “original” Western Cambodian parasite looked like, before the founder populations emerged. Five CB parasites have been identified that were collected around 1992-1993. The Dutch Marines were in Sok San from June 1992 through November 1993. This is the period they started seeing high levels of mefloquine resistance emerge. These samples are all resistant to chloroquine, mefloquine and quinine. Further phenotyping is underway and these data will be shared. Five cryopreserved samples collected in the course of an earlier study were revived and placed in culture in Dennis Kyle's lab. DNA extracted from these samples was processed through WGS at Wellcome Sanger Institute. The sequences will be analysed to compare these genomes to those of current parasites from Cambodia and its neighbouring countries. Through the analysis of haplotypes and ancestry we hope to be able to reconstruct a model for the emergence of resistance to antimalarials in this region.