Sexually transmitted infections are on the rise, putting more people at risk as they spread. Chlamydia rates have nearly doubled since 2000, while the rate of gonorrhea went up by 50% over the same period. The Centers for Disease Control and Prevention reports that syphilis rates are reaching levels last seen in the 1950s.
But some regions of the U.S. are seeing higher rates than others.
Stacker used CDC data to look at which counties reported the highest rate of sexually transmitted infections in South Carolina. Counties are ranked by the rate of chlamydia infections, the most prominent STI at the national level, with gonorrhea and then syphilis rates serving as tiebreakers. This story focuses on bacterial infections, which can be cured, rather than viral infections such as HIV and herpes. At the county level, 2021 cases are the most recent available from the CDC, but state and national-level data for 2022 are also included. This story focuses on sexual transmissions and does not include congenital syphilis cases that were inherited from the mother.
Condoms are the most effective way to prevent the spread of STIs for people with multiple sexual partners, but research has found a decreasing rate of condom use among straight, bisexual, and gay male populations.
During the HIV/AIDS epidemic throughout the 1980s and 1990s, public health efforts advocating for condom use helped curb the spread of the virus. Today, however, condoms are no longer the only tool. Pills such as PrEP lower the risk of contracting HIV from sex by as much as 99%.
While more recent data is not available, the latest CDC survey from 2011-2015 showed less than half of unmarried men used condoms during the last time they had sex.
Among high school students having sex, the share using condoms has fallen from 60% in 2011 to 52% in 2021. While one-third of sexually active students used hormonal birth control, only 10% used both condoms and birth control. Methods like the pill and IUDs are effective at preventing pregnancy but do not stop the spread of STIs.
Chlamydia, gonorrhea, and syphilis are technically bacterial infections—meaning they can be cured with antibiotics—but they can still have lasting health impacts, including pelvic inflammatory disease and infertility. These risks are heightened when left untreated, which many STIs are as they don't obviously present themselves.
The CDC recommends annual testing for cisgender women, transgender men, and gender-nonconforming people with cervixes. It also recommends annual testing for males with male sexual partners. People in these groups who frequently have sex with anonymous partners should be tested every three to six months. Anyone with symptoms should always get tested according to the guidelines.
The CDC says there is little evidence that screening among straight men lowers the spread, and the agency's limited budget is put towards programs benefiting the most at-risk groups. However, some public health groups advocate for testing among all people regardless of sex and sexual orientation.
Data from the National Survey of Family Growth shows men on average have more opposite-sex sexual partners than women, and some argue that catching STIs throughout a sexual network rather than just for the most at-risk groups could curb their spread.
Soon, a pill may also help counter the spread of STIs. DoxyPEP can be taken 24 to 72 hours after unprotected sex and stops an STI before it becomes spreadable and symptomatic. The CDC has shared proposed guidelines recommending it for men who have sex with men and transgender women. The drug was originally approved for treating inhalation of anthrax, and doctors can prescribe it for off-label use.
Read on to see how STI infection rates in South Carolina compare nationally, and the top counties.
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Emma Rubin // Stacker
1 / 47State-level statistics
- Chlamydia cases: 672.5 per 100K (#4 nationally, 35,525 cases)
- Gonorrhea cases: 271.7 per 100K (#6 nationally, 14,352 cases)
- Primary and secondary syphilis cases: 19.6 per 100K (#21 nationally, 1,033 cases)
#46. Mccormick County
- Chlamydia cases: 348.4 per 100K people (34 cases)
- Gonorrhea cases: 143.4 per 100K people (14 cases)
- Syphilis cases (non-congenital): 20.5 per 100K people (2 cases)
--- Primary and secondary syphilis: 10.2 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 10.2 per 100K people (1 case)
#45. Saluda County
- Chlamydia cases: 430.4 per 100K people (81 case)
- Gonorrhea cases: 164.7 per 100K people (31 case)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
#44. Abbeville County
- Chlamydia cases: 440.3 per 100K people (107 cases)
- Gonorrhea cases: 296.3 per 100K people (72 cases)
- Syphilis cases (non-congenital): 20.6 per 100K people (5 cases)
--- Primary and secondary syphilis: 20.6 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 0 cases
#43. Beaufort County
- Chlamydia cases: 449.5 per 100K people (862 cases)
- Gonorrhea cases: 131.4 per 100K people (252 cases)
- Syphilis cases (non-congenital): 12.5 per 100K people (24 cases)
--- Primary and secondary syphilis: 5.2 per 100K people (10 cases)
--- Nonprimary and nonsecondary early syphilis: 7.3 per 100K people (14 cases)
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#42. Georgetown County
- Chlamydia cases: 459.9 per 100K people (294 cases)
- Gonorrhea cases: 192.4 per 100K people (123 cases)
- Syphilis cases (non-congenital): 17.2 per 100K people (11 case)
--- Primary and secondary syphilis: 6.3 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 11.0 per 100K people (7 cases)
#41. Lancaster County
- Chlamydia cases: 463.4 per 100K people (465 cases)
- Gonorrhea cases: 192.4 per 100K people (193 cases)
- Syphilis cases (non-congenital): 11.0 per 100K people (11 case)
--- Primary and secondary syphilis: 5.0 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 6.0 per 100K people (6 cases)
#40. Anderson County
- Chlamydia cases: 470.7 per 100K people (974 cases)
- Gonorrhea cases: 293.4 per 100K people (607 cases)
- Syphilis cases (non-congenital): 50.3 per 100K people (104 cases)
--- Primary and secondary syphilis: 32.9 per 100K people (68 cases)
--- Nonprimary and nonsecondary early syphilis: 17.4 per 100K people (36 cases)
#39. Berkeley County
- Chlamydia cases: 475.7 per 100K people (1,126 cases)
- Gonorrhea cases: 186.3 per 100K people (441 case)
- Syphilis cases (non-congenital): 25.8 per 100K people (61 case)
--- Primary and secondary syphilis: 8.9 per 100K people (21 case)
--- Nonprimary and nonsecondary early syphilis: 16.9 per 100K people (40 cases)
Malachi Jacobs // Shutterstock
10 / 47#38. Calhoun County
- Chlamydia cases: 501.2 per 100K people (71 case)
- Gonorrhea cases: 225.9 per 100K people (32 cases)
- Syphilis cases (non-congenital): 21.2 per 100K people (3 cases)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 21.2 per 100K people (3 cases)
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#37. Oconee County
- Chlamydia cases: 511.3 per 100K people (405 cases)
- Gonorrhea cases: 221.0 per 100K people (175 cases)
- Syphilis cases (non-congenital): 11.4 per 100K people (9 cases)
--- Primary and secondary syphilis: 7.6 per 100K people (6 cases)
--- Nonprimary and nonsecondary early syphilis: 3.8 per 100K people (3 cases)
Bennekom // Shutterstock
12 / 47#36. Edgefield County
- Chlamydia cases: 512.4 per 100K people (134 cases)
- Gonorrhea cases: 240.9 per 100K people (63 cases)
- Syphilis cases (non-congenital): 26.8 per 100K people (7 cases)
--- Primary and secondary syphilis: 11.5 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 15.3 per 100K people (4 cases)
#35. Lexington County
- Chlamydia cases: 516.1 per 100K people (1,549 cases)
- Gonorrhea cases: 196.9 per 100K people (591 case)
- Syphilis cases (non-congenital): 24.0 per 100K people (72 cases)
--- Primary and secondary syphilis: 10.7 per 100K people (32 cases)
--- Nonprimary and nonsecondary early syphilis: 13.3 per 100K people (40 cases)
#34. Aiken County
- Chlamydia cases: 522.3 per 100K people (892 cases)
- Gonorrhea cases: 251.8 per 100K people (430 cases)
- Syphilis cases (non-congenital): 32.8 per 100K people (56 cases)
--- Primary and secondary syphilis: 18.2 per 100K people (31 case)
--- Nonprimary and nonsecondary early syphilis: 14.6 per 100K people (25 cases)
Nolichuckyjake // Shutterstock
15 / 47#33. York County
- Chlamydia cases: 534.0 per 100K people (1,541 case)
- Gonorrhea cases: 214.1 per 100K people (618 cases)
- Syphilis cases (non-congenital): 14.2 per 100K people (41 case)
--- Primary and secondary syphilis: 8.3 per 100K people (24 cases)
--- Nonprimary and nonsecondary early syphilis: 5.9 per 100K people (17 cases)
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#32. Horry County
- Chlamydia cases: 540.0 per 100K people (1,974 cases)
- Gonorrhea cases: 244.3 per 100K people (893 cases)
- Syphilis cases (non-congenital): 29.8 per 100K people (109 cases)
--- Primary and secondary syphilis: 13.1 per 100K people (48 cases)
--- Nonprimary and nonsecondary early syphilis: 16.7 per 100K people (61 case)
#31. Spartanburg County
- Chlamydia cases: 546.9 per 100K people (1,837 cases)
- Gonorrhea cases: 255.2 per 100K people (857 cases)
- Syphilis cases (non-congenital): 31.0 per 100K people (104 cases)
--- Primary and secondary syphilis: 13.7 per 100K people (46 cases)
--- Nonprimary and nonsecondary early syphilis: 17.3 per 100K people (58 cases)
#30. Pickens County
- Chlamydia cases: 565.7 per 100K people (748 cases)
- Gonorrhea cases: 226.9 per 100K people (300 cases)
- Syphilis cases (non-congenital): 43.9 per 100K people (58 cases)
--- Primary and secondary syphilis: 29.5 per 100K people (39 cases)
--- Nonprimary and nonsecondary early syphilis: 14.4 per 100K people (19 cases)
#29. Kershaw County
- Chlamydia cases: 576.1 per 100K people (381 case)
- Gonorrhea cases: 231.4 per 100K people (153 cases)
- Syphilis cases (non-congenital): 24.2 per 100K people (16 cases)
--- Primary and secondary syphilis: 6.0 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 18.1 per 100K people (12 cases)
#28. Greenville County
- Chlamydia cases: 644.0 per 100K people (3,438 cases)
- Gonorrhea cases: 294.5 per 100K people (1,572 cases)
- Syphilis cases (non-congenital): 53.0 per 100K people (283 cases)
--- Primary and secondary syphilis: 23.0 per 100K people (123 cases)
--- Nonprimary and nonsecondary early syphilis: 30.0 per 100K people (160 cases)
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#27. Cherokee County
- Chlamydia cases: 645.8 per 100K people (362 cases)
- Gonorrhea cases: 360.4 per 100K people (202 cases)
- Syphilis cases (non-congenital): 19.6 per 100K people (11 case)
--- Primary and secondary syphilis: 10.7 per 100K people (6 cases)
--- Nonprimary and nonsecondary early syphilis: 8.9 per 100K people (5 cases)
#26. Jasper County
- Chlamydia cases: 659.5 per 100K people (200 cases)
- Gonorrhea cases: 148.4 per 100K people (45 cases)
- Syphilis cases (non-congenital): 23.1 per 100K people (7 cases)
--- Primary and secondary syphilis: 3.3 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 19.8 per 100K people (6 cases)
#25. Colleton County
- Chlamydia cases: 660.4 per 100K people (254 cases)
- Gonorrhea cases: 267.8 per 100K people (103 cases)
- Syphilis cases (non-congenital): 15.6 per 100K people (6 cases)
--- Primary and secondary syphilis: 5.2 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 10.4 per 100K people (4 cases)
#24. Laurens County
- Chlamydia cases: 693.2 per 100K people (470 cases)
- Gonorrhea cases: 348.1 per 100K people (236 cases)
- Syphilis cases (non-congenital): 33.9 per 100K people (23 cases)
--- Primary and secondary syphilis: 22.1 per 100K people (15 cases)
--- Nonprimary and nonsecondary early syphilis: 11.8 per 100K people (8 cases)
#23. Dorchester County
- Chlamydia cases: 731.7 per 100K people (1,195 cases)
- Gonorrhea cases: 272.5 per 100K people (445 cases)
- Syphilis cases (non-congenital): 23.9 per 100K people (39 cases)
--- Primary and secondary syphilis: 12.9 per 100K people (21 case)
--- Nonprimary and nonsecondary early syphilis: 11.0 per 100K people (18 cases)
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#22. Union County
- Chlamydia cases: 736.6 per 100K people (199 cases)
- Gonorrhea cases: 329.4 per 100K people (89 cases)
- Syphilis cases (non-congenital): 33.3 per 100K people (9 cases)
--- Primary and secondary syphilis: 29.6 per 100K people (8 cases)
--- Nonprimary and nonsecondary early syphilis: 3.7 per 100K people (1 case)
#21. Clarendon County
- Chlamydia cases: 738.1 per 100K people (229 cases)
- Gonorrhea cases: 319.1 per 100K people (99 cases)
- Syphilis cases (non-congenital): 19.3 per 100K people (6 cases)
--- Primary and secondary syphilis: 12.9 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 6.4 per 100K people (2 cases)
Chansak Joe // Shutterstock
28 / 47#20. Chesterfield County
- Chlamydia cases: 744.2 per 100K people (322 cases)
- Gonorrhea cases: 325.9 per 100K people (141 case)
- Syphilis cases (non-congenital): 23.1 per 100K people (10 cases)
--- Primary and secondary syphilis: 20.8 per 100K people (9 cases)
--- Nonprimary and nonsecondary early syphilis: 2.3 per 100K people (1 case)
#19. Charleston County
- Chlamydia cases: 761.9 per 100K people (3,147 cases)
- Gonorrhea cases: 293.4 per 100K people (1,212 cases)
- Syphilis cases (non-congenital): 46.5 per 100K people (192 cases)
--- Primary and secondary syphilis: 22.5 per 100K people (93 cases)
--- Nonprimary and nonsecondary early syphilis: 24.0 per 100K people (99 cases)
#18. Chester County
- Chlamydia cases: 797.9 per 100K people (257 cases)
- Gonorrhea cases: 347.7 per 100K people (112 cases)
- Syphilis cases (non-congenital): 27.9 per 100K people (9 cases)
--- Primary and secondary syphilis: 6.2 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 21.7 per 100K people (7 cases)
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#17. Greenwood County
- Chlamydia cases: 798.7 per 100K people (553 cases)
- Gonorrhea cases: 407.3 per 100K people (282 cases)
- Syphilis cases (non-congenital): 41.9 per 100K people (29 cases)
--- Primary and secondary syphilis: 24.6 per 100K people (17 cases)
--- Nonprimary and nonsecondary early syphilis: 17.3 per 100K people (12 cases)
#16. Fairfield County
- Chlamydia cases: 845.8 per 100K people (175 cases)
- Gonorrhea cases: 464.0 per 100K people (96 cases)
- Syphilis cases (non-congenital): 43.5 per 100K people (9 cases)
--- Primary and secondary syphilis: 19.3 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 24.2 per 100K people (5 cases)
C Dash // Shutterstock
33 / 47#15. Barnwell County
- Chlamydia cases: 869.8 per 100K people (179 cases)
- Gonorrhea cases: 403.3 per 100K people (83 cases)
- Syphilis cases (non-congenital): 9.7 per 100K people (2 cases)
--- Primary and secondary syphilis: 4.9 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 4.9 per 100K people (1 case)
SevenMaps // Shutterstock
34 / 47#14. Bamberg County
- Chlamydia cases: 902.3 per 100K people (119 cases)
- Gonorrhea cases: 485.3 per 100K people (64 cases)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
#13. Florence County
- Chlamydia cases: 906.9 per 100K people (1,238 cases)
- Gonorrhea cases: 490.1 per 100K people (669 cases)
- Syphilis cases (non-congenital): 43.2 per 100K people (59 cases)
--- Primary and secondary syphilis: 21.2 per 100K people (29 cases)
--- Nonprimary and nonsecondary early syphilis: 22.0 per 100K people (30 cases)
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#12. Newberry County
- Chlamydia cases: 929.0 per 100K people (353 cases)
- Gonorrhea cases: 444.8 per 100K people (169 cases)
- Syphilis cases (non-congenital): 5.3 per 100K people (2 cases)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 5.3 per 100K people (2 cases)
Jen Wolf // Shutterstock
37 / 47#11. Hampton County
- Chlamydia cases: 929.6 per 100K people (169 cases)
- Gonorrhea cases: 269.5 per 100K people (49 cases)
- Syphilis cases (non-congenital): 11.0 per 100K people (2 cases)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 11.0 per 100K people (2 cases)
Jared Freye // Shutterstock
38 / 47#10. Darlington County
- Chlamydia cases: 988.0 per 100K people (620 cases)
- Gonorrhea cases: 583.2 per 100K people (366 cases)
- Syphilis cases (non-congenital): 31.9 per 100K people (20 cases)
--- Primary and secondary syphilis: 19.1 per 100K people (12 cases)
--- Nonprimary and nonsecondary early syphilis: 12.7 per 100K people (8 cases)
Wilma Engelhardt Ellis // Shutterstock
39 / 47#9. Marlboro County
- Chlamydia cases: 1,004.5 per 100K people (265 cases)
- Gonorrhea cases: 428.3 per 100K people (113 cases)
- Syphilis cases (non-congenital): 37.9 per 100K people (10 cases)
--- Primary and secondary syphilis: 30.3 per 100K people (8 cases)
--- Nonprimary and nonsecondary early syphilis: 7.6 per 100K people (2 cases)
#8. Lee County
- Chlamydia cases: 1,013.5 per 100K people (165 cases)
- Gonorrhea cases: 589.7 per 100K people (96 cases)
- Syphilis cases (non-congenital): 55.3 per 100K people (9 cases)
--- Primary and secondary syphilis: 30.7 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 24.6 per 100K people (4 cases)
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#7. Sumter County
- Chlamydia cases: 1,020.4 per 100K people (1,069 cases)
- Gonorrhea cases: 441.0 per 100K people (462 cases)
- Syphilis cases (non-congenital): 31.5 per 100K people (33 cases)
--- Primary and secondary syphilis: 15.3 per 100K people (16 cases)
--- Nonprimary and nonsecondary early syphilis: 16.2 per 100K people (17 cases)
Brian Nolan // Shutterstock
42 / 47#6. Marion County
- Chlamydia cases: 1,045.7 per 100K people (301 case)
- Gonorrhea cases: 437.7 per 100K people (126 cases)
- Syphilis cases (non-congenital): 31.3 per 100K people (9 cases)
--- Primary and secondary syphilis: 17.4 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 13.9 per 100K people (4 cases)
Bennekom // Shutterstock
43 / 47#5. Allendale County
- Chlamydia cases: 1,158.1 per 100K people (91 case)
- Gonorrhea cases: 470.9 per 100K people (37 cases)
- Syphilis cases (non-congenital): 25.5 per 100K people (2 cases)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 25.5 per 100K people (2 cases)
SevenMaps // Shutterstock
44 / 47#4. Williamsburg County
- Chlamydia cases: 1,161.3 per 100K people (354 cases)
- Gonorrhea cases: 531.4 per 100K people (162 cases)
- Syphilis cases (non-congenital): 42.6 per 100K people (13 cases)
--- Primary and secondary syphilis: 9.8 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 32.8 per 100K people (10 cases)
Kristi Blokhin // Shutterstock
45 / 47#3. Dillon County
- Chlamydia cases: 1,171.4 per 100K people (329 cases)
- Gonorrhea cases: 494.9 per 100K people (139 cases)
- Syphilis cases (non-congenital): 28.5 per 100K people (8 cases)
--- Primary and secondary syphilis: 7.1 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 21.4 per 100K people (6 cases)
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James R Poston // Shutterstock
46 / 47#2. Orangeburg County
- Chlamydia cases: 1,172.8 per 100K people (973 cases)
- Gonorrhea cases: 530.4 per 100K people (440 cases)
- Syphilis cases (non-congenital): 25.3 per 100K people (21 case)
--- Primary and secondary syphilis: 8.4 per 100K people (7 cases)
--- Nonprimary and nonsecondary early syphilis: 16.9 per 100K people (14 cases)
#1. Richland County
- Chlamydia cases: 1,344.2 per 100K people (5,623 cases)
- Gonorrhea cases: 577.6 per 100K people (2,416 cases)
- Syphilis cases (non-congenital): 69.6 per 100K people (291 case)
--- Primary and secondary syphilis: 22.9 per 100K people (96 cases)
--- Nonprimary and nonsecondary early syphilis: 46.6 per 100K people (195 cases)
This story features data reporting and writing by Emma Rubin and is part of a series utilizing data automation across 49 states.
