Syphilis is not smallpox. Although these are both infectious diseases, the two infectious diseases are completely different in the way they are transmitted as well as the pathogens. The pathogen of syphilis is the pale dense spirochete pale subspecies, which is a cellular organism. The pathogen of smallpox, on the other hand, is a virus. Viruses cannot survive independently outside the body, while syphilis spirochetes can survive independently outside the body. Smallpox is a more serious and easily contagious infection that can cause death in some people, and is acute. Smallpox can cause a rash all over the body and can leave scars afterwards. Smallpox has been eradicated from the world, and there is no longer an epidemic of the disease in humans. Syphilis is mostly transmitted through sexual transmission. Syphilis can also produce a rash, but the form of the rash is different from smallpox, and there are various forms of rash such as hard chancre and syphilis rash. Smallpox is transmitted mainly through the respiratory tract.