Syphilis is a bacterial infection (Treponema pallidum) that is most often spread by sexual contact. The infection usually causes disease over a course of several years. In the early stages, syphilis causes disease of the genitals, mucous membranes and skin. If it is not treated, syphilis can lead to serious problems, such as heart problems, neurological problems (neurosyphilis), blindness, dementia, and death.
Since 1996, rates of syphilis have been increasing in the United States, notably among men who have sex with other men.
Syphilis is passed from person to person through direct contact with a syphilis sore or lesion, usually during vaginal, anal or oral sex. Pregnant women with the disease can pass it to the babies. Syphilis cannot be spread by toilet seats, door knobs, swimming pools, hot tubs, bath tubs, shared clothing, or eating utensils.
While the health problems caused by syphilis in adults and newborns are serious in their own right, the genital sores caused by syphilis in adults also make it easier to sexually transmit or acquire HIV infection.
Studies suggest that people with HIV who become infected with syphilis may be more likely to develop lesions and may have a faster progression of syphilis disease. A person with HIV may also temporarily see their CD4 cells drop and HIV levels rise during early syphilis, but then improve after being treated.