The CDC's Sexually Transmitted Disease Surveillance Report says that 2 million cases were reported overall in 2016. Over 75% of those (1.6 million) were cases of chlamydia, half of them reported among young women.
Syphilis rates grew nearly 18% between 2015 and 2016, most of those cases reported by men, particularly homosexual and bisexual men. Half of the latter also have HIV, according to the report. Syphilis infections also rose a whopping 36% among women and 28% among newborns in the same period, with over 600 cases of syphilis infection among newborns reported, often resulting in severe health complications and even death.
Gonorrhea infection rates also rose, by 22% among men (and again especially among gays and bisexuals), with 470,000 reported. 28,000 cases of syphilis were also reported in 2016, a rise of nearly 18% over the 2015 figures.
The CDC warned that together, these figures were "the highest number ever" on record. The three diseases are treatable, but if not timely or properly diagnosed, may lead to infertility or stillbirth, increased risk of HIV infection, and other health complications.
Dr. Jonathan Mermin, director of the CDC's center on STD and TB prevention, said in an agency press release that the increase in STD rates was "a clear warning of a growing threat."