As syphilis levels hit 70-year high, sexually transmitted infection epidemic shows 'no signs of slowing'

illustration of the spiral shaped bacteria that cause syphilis

More than 2.5 million cases of chlamydia, gonorrhea and syphilis were reported in the U.S. in 2021 — nearly 6% more than were reported in 2020. 

Syphilis rates, in particular, leapt to levels not seen since the 1950s. More than 176,000 cases of syphilis were reported in 2021, up from nearly 134,000 in 2020. Rates of the bacterial sexually transmitted infection (STI) reached historic lows in the early 2000s — when they hovered around 30,000 per year — but they have climbed steadily since then, according to finalized data released by the Centers for Disease Control and Prevention (CDC) on Tuesday (April 11).