Syphilis is a sexually transmitted infection (STI) caused by a type of bacteria known as Treponema pallidum.
In 2019, 129,813 cases of syphilisTrusted Source were reported in the United States, according to the Centers for Disease Control and Prevention (CDC). The rates of syphilis are rising overall,Trusted Source including in people with vaginas. Though rates are lower in people with penises, rates are still on the rise.
