FACTBOX: Quick guide to syphilis

(Reuters) - New genetic evidence supports the theory that Christopher Columbus and his crew brought syphilis to Europe on the way back from their 1492 exploration of the Americas.

Following are facts about syphilis:

* Syphilis is a sexually transmitted disease caused by the Treponema pallidum bacterium. Because its symptoms mimic those of other diseases, it is often called "the great imitator."

* Syphilis starts out with a painless sore at the site of infection, which often disappears without treatment.

* Weeks later, a rash appears that can cover any part of the body, including the palms of the hands and the soles of the feet. This may be accompanied by fever, fatigue and aches and pains. These signs appear and disappear for up to a year.

* In the tertiary stage, the bacteria may spread to internal organs including to the brain, causing numbness, paralysis, deafness and dementia. It may also cause heart trouble, including an inflammation of the aorta or heart valve problems.

* With early diagnosis, syphilis can be easily be treated with antibiotics.

* Before the advent of penicillin in the 1940s, syphilis had been treated in a range of uncomfortable ways, from toxic mercury to a risky practice of infecting victims with malaria in the hope that the fever would kill off the syphilis.

* Deborah Hayden, author of "Pox: Genius, Madness and the Mysteries of Syphilis," estimates that at its peak in the 19th century, syphilis may have infected as much as 15 percent of adults in Europe and North America.

* In a 2001 report, the World Health Organization estimated that there were an estimated 12 million cases of syphilis a year.

(Reporting by Julie Steenhuysen; Editing by Stacey Joyce)