Syphilis is a curable sexually transmitte disease caused by the Treponema pallidum spirochete. The route of transmission of syphilis is almost always by sexual contact, although there are examples of congenital syphilis via transmission from mother to child in utero. The signs and symptoms of syphilis are numerous; before the advent of serological testing, precise diagnosis was very difficult. In fact, the disease was dubbed the "Great Imitator" because it was often confused with other diseases, particularly in its tertiary stage. Syphilis (unless antibiotic-resistant) can be easily treated with antibiotics including penicillin. The oldest and still most effective method is an intramuscular injection of benzathine penicillin. If not treated, syphilis can cause serious effects such as damage to the heart, aorta, brain, eyes, and bones. In some cases these effects can be fatal. In 1998, the complete genetic sequence of T. pallidum was published which may aid understanding of the pathogenesis of syphilis.