Syphilis is a sexually transmitted disease caused by a bacteria (Treponema pallidum).
The first sign of infection is a very infectious but painless sore (primary chancre). There is usually a marked rash in the secondary stage illness, a month or two later. Two to twenty years later the brain can be affected, and also the the main artery from the heart (the aorta). Both these consequences can be fatal.
Infants can catch syphilis from their mothers before birth and are then born with a condition known as congenital syphilis. They may also be born underweight.
Syphilis caused 0.3% of all deaths worldwide in 2002 or 25 deaths per million people.