Sexually transmitted infections like chlamydia, gonorrhea and syphilis soared to new record highs in the United States last year, public health officials said Tuesday.
The reasons for the rise were not immediately clear, but the CDC pointed to prior research that has shown factors like poverty, stigma, discrimination and drug use can boost STD rates.
Nearly 2.3 million cases of chlamydia, gonorrhea, and syphilis were diagnosed in the United States in 2017, said the Centers for Disease Control and Prevention.
"This surpassed the previous record set in 2016 by more than 200,000 cases," the CDC said in a statement.
Between 2013 and 2017, syphilis diagnoses spiked 76 percent, going from 17,375 to 30,644 cases.
Men who have sex with men made up almost 70 percent of syphilis cases.
Over those four years, gonorrhea cases increased 67 percent -- from 333,004 to 555,608 cases.
Gonorrhea diagnoses nearly doubled among gay men -- going from 169,130 cases in 2013 to 322,169 last year.
Increases in gonorrhea among women "are also concerning," said the CDC report, with cases going from 197,499 to 232,587 in a single year from 2016-2017.
Chlamydia remained the most common condition, with more than 1.7 million cases diagnosed in 2017.
Almost half -- 45 percent -- of chlamydia diagnoses were among 15- to 24-year-old females.
"We are sliding backward," said Jonathan Mermin, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention.
"It is evident the systems that identify, treat, and ultimately prevent STDs are strained to near-breaking point."
Chlamydia, gonorrhea, and syphilis can be cured with antibiotics.
But often, the infections go undiagnosed and untreated, and may lead to infertility, ectopic pregnancy, stillbirth in infants, and increased HIV risk.
Public health experts are also concerned about antibiotic resistant gonorrhea.
Ceftriaxone is the only remaining effective antibiotic for treating gonorrhea in the United States.