Sexually transmitted infections are transmitted from an infected person to an uninfected person through sexual contact. STIs can be caused by bacteria, viruses or parasites and include diseases like HIV/AIDS and gonorrhea. STIs, in particular HIV, are prevalent around the world, and can sometimes require expensive, life-long treatments to maintain remission. This creates a significant economic strain which can be accompanied by political instability, particularly in developing countries. In military contexts, STIs can be a significant danger to the walking blood bank during combat casualty care, making effective screening and prevention strategies a top priority for deployed medicine. AFRIMS maintains significant medical infrastructure in Southeast Asia to track STIs to understand how pathogens evolve and how they cause disease to inform the development of diagnostics, drugs and vaccines and has led in several field-leading accomplishments including the RV144 HIV vaccine trial, currently the only HIV vaccine trial worldwide to demonstrate partial efficacy.