Duncan obtained his PhD from Portsmouth Polytechnic, UK in 1987.  He undertook a Post-Doctoral fellowship at the Institute of Molecular and Cell Biology in Singapore and then undertook research in hospitals in Singapore for the next ten years primarily on molecular mechanisms of cancer.  He became interested in virology when he moved to Mahidol University in 2000.

His interests focus on viral infectious diseases, particularly mosquito-transmitted viruses, with a particular interest in understanding the interactions between host cells and viral pathogens as an aid to developing novel therapeutics. He has published over 200 scientific articles and book chapters and currently serves as an Editor for the Journal of Virological Methods.