1 INTRODUCTION Syphilis is a bacterial infection with increasing incidence in many countries including the US,1-3 despite the availability of effective antibiotics for many decades.4 Although the causative agent, Treponema pallidum, is predominantly transmitted through sexual contact, it has been recognized as a transfusion-transmitted infection (TTI) since the early 20th century, and testing of blood donations is routinely performed in most countries.5, 6 Because many cases are asymptomatic,...