Syphilis: Syphilis: A sexually transmitted disease caused by Treponema pallidum, a microscopic organism called a spirochete. This worm-like, spiral-shaped organism infects people by burrowing into the moist mucous membranes of the mouth or genitals. From there, the spirochete produces a non-painful ulcer known as a chancre. There are three stages of syphilis. The first (primary) stage: This involves the formation of the chancre. At this stage, syphilis is highly contagious. The primary stage can last one to five weeks. The disease can be transmitted from any contact with one of the ulcers, which are teeming with spirochetes. If the ulcer is outside of the vagina or on the scrotum, the use of condoms may not help in preventing transmission. Likewise, if the ulcer is in the mouth, merely kissing the infected individual can spread syphilis. Even without treatment, the early infection resolves on its own in most women. The second (secondary) stage: However, 25 percent of cases will proceed to the secondary stage of syphilis, which lasts four to six weeks. This phase can include hair loss; a sore throat; white patches in the nose, mouth, and vagina; fever; headaches; and a skin rash. There can be lesions on the genitals that look like genital warts, but are caused by spirochetes rather than the wart virus. These wart-like lesions, as well as the skin rash, are highly contagious. The rash can occur on the palms of the hands, and the infection can be transmitted by casual contact. The third (tertiary) stage: This final stage of the disease involves the brain and heart, and is usually no longer contagious. At this point, however, the infection can cause extensive damage to the internal organs and the brain, and can lead to death.Diagnosis is by blood test, either the rapid plasma reagin (RPR) or Venereal Disease Research Laboratory (VDRL) test. Treatment is with antibiotics.