Kanchanaburi province is located in the Western Central region of Thailand. It is about 129 kilometers west of Bangkok Metropolis, the capital city. Kanchanaburi is Thailand's third largest province, covering an area of 19,486 square kilometers. The Health and Demographic Surveillance System (HDSS) area consists of 100 villages/enumeration districts scattered throughout Kanchanaburi province. The field research centre is located at the new Mahidol University campus in Saiyok district of Kanchanaburi.