Counties with the highest STI rates in Indiana

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March 18, 2024
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Counties with the highest STI rates in Indiana

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 Indiana. 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 Indiana compare nationally, and the top counties.

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Emma Rubin // Stacker

State-level statistics

- Chlamydia cases: 495.2 per 100K (#21 nationally, 33,834 cases)
- Gonorrhea cases: 181.4 per 100K (#23 nationally, 12,396 cases)
- Primary and secondary syphilis cases: 10.0 per 100K (#41 nationally, 686 cases)
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Roberto Galan // Shutterstock

#50. Sullivan County

- Chlamydia cases: 269.8 per 100K people (56 cases)
- Gonorrhea cases: 159.0 per 100K people (33 cases)
- Syphilis cases (non-congenital): 4.8 per 100K people (1 case)
--- Primary and secondary syphilis: 4.8 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#49. Orange County

- Chlamydia cases: 277.4 per 100K people (55 cases)
- Gonorrhea cases: 55.5 per 100K people (11 case)
- Syphilis cases (non-congenital): 5.0 per 100K people (1 case)
--- Primary and secondary syphilis: 5.0 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#48. Daviess County

- Chlamydia cases: 278.5 per 100K people (93 cases)
- Gonorrhea cases: 53.9 per 100K people (18 cases)
- Syphilis cases (non-congenital): 18.0 per 100K people (6 cases)
--- Primary and secondary syphilis: 12.0 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 6.0 per 100K people (2 cases)
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#47. Porter County

- Chlamydia cases: 279.5 per 100K people (487 cases)
- Gonorrhea cases: 62.0 per 100K people (108 cases)
- Syphilis cases (non-congenital): 6.9 per 100K people (12 cases)
--- Primary and secondary syphilis: 5.2 per 100K people (9 cases)
--- Nonprimary and nonsecondary early syphilis: 1.7 per 100K people (3 cases)
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#46. Jennings County

- Chlamydia cases: 280.9 per 100K people (77 cases)
- Gonorrhea cases: 58.4 per 100K people (16 cases)
- Syphilis cases (non-congenital): 3.6 per 100K people (1 case)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 3.6 per 100K people (1 case)
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#45. Fayette County

- Chlamydia cases: 282.5 per 100K people (66 cases)
- Gonorrhea cases: 77.1 per 100K people (18 cases)
- Syphilis cases (non-congenital): 12.8 per 100K people (3 cases)
--- Primary and secondary syphilis: 4.3 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 8.6 per 100K people (2 cases)
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#44. Miami County

- Chlamydia cases: 282.7 per 100K people (102 cases)
- Gonorrhea cases: 121.9 per 100K people (44 cases)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#43. Warrick County

- Chlamydia cases: 289.9 per 100K people (187 cases)
- Gonorrhea cases: 108.5 per 100K people (70 cases)
- Syphilis cases (non-congenital): 12.4 per 100K people (8 cases)
--- Primary and secondary syphilis: 9.3 per 100K people (6 cases)
--- Nonprimary and nonsecondary early syphilis: 3.1 per 100K people (2 cases)
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#42. Shelby County

- Chlamydia cases: 295.3 per 100K people (133 cases)
- Gonorrhea cases: 71.0 per 100K people (32 cases)
- Syphilis cases (non-congenital): 13.3 per 100K people (6 cases)
--- Primary and secondary syphilis: 11.1 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 2.2 per 100K people (1 case)
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#41. Jay County

- Chlamydia cases: 296.3 per 100K people (60 cases)
- Gonorrhea cases: 69.1 per 100K people (14 cases)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#40. Jasper County

- Chlamydia cases: 302.2 per 100K people (100 cases)
- Gonorrhea cases: 42.3 per 100K people (14 cases)
- Syphilis cases (non-congenital): 9.1 per 100K people (3 cases)
--- Primary and secondary syphilis: 6.0 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 3.0 per 100K people (1 case)
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#39. Scott County

- Chlamydia cases: 307.9 per 100K people (75 cases)
- Gonorrhea cases: 131.4 per 100K people (32 cases)
- Syphilis cases (non-congenital): 8.2 per 100K people (2 cases)
--- Primary and secondary syphilis: 4.1 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 4.1 per 100K people (1 case)
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#38. Benton County

- Chlamydia cases: 309.8 per 100K people (27 cases)
- Gonorrhea cases: 45.9 per 100K people (4 cases)
- Syphilis cases (non-congenital): 11.5 per 100K people (1 case)
--- Primary and secondary syphilis: 11.5 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#37. Decatur County

- Chlamydia cases: 315.3 per 100K people (83 cases)
- Gonorrhea cases: 79.8 per 100K people (21 case)
- Syphilis cases (non-congenital): 15.2 per 100K people (4 cases)
--- Primary and secondary syphilis: 11.4 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 3.8 per 100K people (1 case)
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#36. Randolph County

- Chlamydia cases: 315.7 per 100K people (77 cases)
- Gonorrhea cases: 114.8 per 100K people (28 cases)
- Syphilis cases (non-congenital): 8.2 per 100K people (2 cases)
--- Primary and secondary syphilis: 4.1 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 4.1 per 100K people (1 case)
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#35. Jefferson County

- Chlamydia cases: 316.8 per 100K people (105 cases)
- Gonorrhea cases: 57.3 per 100K people (19 cases)
- Syphilis cases (non-congenital): 3.0 per 100K people (1 case)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 3.0 per 100K people (1 case)
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#34. Jackson County

- Chlamydia cases: 316.9 per 100K people (146 cases)
- Gonorrhea cases: 73.8 per 100K people (34 cases)
- Syphilis cases (non-congenital): 10.9 per 100K people (5 cases)
--- Primary and secondary syphilis: 6.5 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 4.3 per 100K people (2 cases)
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#33. Clay County

- Chlamydia cases: 318.1 per 100K people (84 cases)
- Gonorrhea cases: 193.1 per 100K people (51 case)
- Syphilis cases (non-congenital): 3.8 per 100K people (1 case)
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 3.8 per 100K people (1 case)
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#32. Greene County

- Chlamydia cases: 321.6 per 100K people (99 cases)
- Gonorrhea cases: 152.7 per 100K people (47 cases)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#31. Johnson County

- Chlamydia cases: 326.2 per 100K people (536 cases)
- Gonorrhea cases: 99.8 per 100K people (164 cases)
- Syphilis cases (non-congenital): 14.0 per 100K people (23 cases)
--- Primary and secondary syphilis: 7.3 per 100K people (12 cases)
--- Nonprimary and nonsecondary early syphilis: 6.7 per 100K people (11 case)
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#30. Gibson County

- Chlamydia cases: 328.0 per 100K people (108 cases)
- Gonorrhea cases: 145.8 per 100K people (48 cases)
- Syphilis cases (non-congenital): 15.2 per 100K people (5 cases)
--- Primary and secondary syphilis: 12.1 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 3.0 per 100K people (1 case)
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#29. Kosciusko County

- Chlamydia cases: 332.1 per 100K people (266 cases)
- Gonorrhea cases: 107.4 per 100K people (86 cases)
- Syphilis cases (non-congenital): 7.5 per 100K people (6 cases)
--- Primary and secondary syphilis: 2.5 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 5.0 per 100K people (4 cases)
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#28. Putnam County

- Chlamydia cases: 338.0 per 100K people (125 cases)
- Gonorrhea cases: 121.7 per 100K people (45 cases)
- Syphilis cases (non-congenital): 16.2 per 100K people (6 cases)
--- Primary and secondary syphilis: 2.7 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 13.5 per 100K people (5 cases)
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#27. Dekalb County

- Chlamydia cases: 339.2 per 100K people (147 cases)
- Gonorrhea cases: 96.9 per 100K people (42 cases)
- Syphilis cases (non-congenital): 0 cases
--- Primary and secondary syphilis: 0 cases
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#26. Floyd County

- Chlamydia cases: 359.2 per 100K people (289 cases)
- Gonorrhea cases: 172.8 per 100K people (139 cases)
- Syphilis cases (non-congenital): 21.1 per 100K people (17 cases)
--- Primary and secondary syphilis: 13.7 per 100K people (11 case)
--- Nonprimary and nonsecondary early syphilis: 7.5 per 100K people (6 cases)
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#25. White County

- Chlamydia cases: 361.0 per 100K people (89 cases)
- Gonorrhea cases: 69.0 per 100K people (17 cases)
- Syphilis cases (non-congenital): 8.1 per 100K people (2 cases)
--- Primary and secondary syphilis: 4.1 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 4.1 per 100K people (1 case)
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#24. Bartholomew County

- Chlamydia cases: 363.7 per 100K people (300 cases)
- Gonorrhea cases: 121.2 per 100K people (100 cases)
- Syphilis cases (non-congenital): 6.1 per 100K people (5 cases)
--- Primary and secondary syphilis: 2.4 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 3.6 per 100K people (3 cases)
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#23. Noble County

- Chlamydia cases: 364.2 per 100K people (172 cases)
- Gonorrhea cases: 133.4 per 100K people (63 cases)
- Syphilis cases (non-congenital): 4.2 per 100K people (2 cases)
--- Primary and secondary syphilis: 2.1 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 2.1 per 100K people (1 case)
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#22. Knox County

- Chlamydia cases: 392.1 per 100K people (141 case)
- Gonorrhea cases: 122.4 per 100K people (44 cases)
- Syphilis cases (non-congenital): 13.9 per 100K people (5 cases)
--- Primary and secondary syphilis: 11.1 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 2.8 per 100K people (1 case)
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#21. Clinton County

- Chlamydia cases: 432.5 per 100K people (143 cases)
- Gonorrhea cases: 151.2 per 100K people (50 cases)
- Syphilis cases (non-congenital): 15.1 per 100K people (5 cases)
--- Primary and secondary syphilis: 12.1 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 3.0 per 100K people (1 case)
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#20. Clark County

- Chlamydia cases: 435.9 per 100K people (535 cases)
- Gonorrhea cases: 174.4 per 100K people (214 cases)
- Syphilis cases (non-congenital): 25.3 per 100K people (31 case)
--- Primary and secondary syphilis: 16.3 per 100K people (20 cases)
--- Nonprimary and nonsecondary early syphilis: 9.0 per 100K people (11 case)
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#19. Laporte County

- Chlamydia cases: 446.7 per 100K people (502 cases)
- Gonorrhea cases: 160.2 per 100K people (180 cases)
- Syphilis cases (non-congenital): 6.2 per 100K people (7 cases)
--- Primary and secondary syphilis: 3.6 per 100K people (4 cases)
--- Nonprimary and nonsecondary early syphilis: 2.7 per 100K people (3 cases)
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#18. Montgomery County

- Chlamydia cases: 459.8 per 100K people (175 cases)
- Gonorrhea cases: 89.3 per 100K people (34 cases)
- Syphilis cases (non-congenital): 7.9 per 100K people (3 cases)
--- Primary and secondary syphilis: 5.3 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 2.6 per 100K people (1 case)
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#17. Cass County

- Chlamydia cases: 463.2 per 100K people (174 cases)
- Gonorrhea cases: 135.8 per 100K people (51 case)
- Syphilis cases (non-congenital): 5.3 per 100K people (2 cases)
--- Primary and secondary syphilis: 5.3 per 100K people (2 cases)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#16. Wayne County

- Chlamydia cases: 472.5 per 100K people (314 cases)
- Gonorrhea cases: 237.8 per 100K people (158 cases)
- Syphilis cases (non-congenital): 19.6 per 100K people (13 cases)
--- Primary and secondary syphilis: 10.5 per 100K people (7 cases)
--- Nonprimary and nonsecondary early syphilis: 9.0 per 100K people (6 cases)
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#15. Fountain County

- Chlamydia cases: 493.1 per 100K people (81 case)
- Gonorrhea cases: 85.2 per 100K people (14 cases)
- Syphilis cases (non-congenital): 18.3 per 100K people (3 cases)
--- Primary and secondary syphilis: 18.3 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#14. Elkhart County

- Chlamydia cases: 501.6 per 100K people (1,038 cases)
- Gonorrhea cases: 185.1 per 100K people (383 cases)
- Syphilis cases (non-congenital): 10.6 per 100K people (22 cases)
--- Primary and secondary syphilis: 5.3 per 100K people (11 case)
--- Nonprimary and nonsecondary early syphilis: 5.3 per 100K people (11 case)
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#13. Parke County

- Chlamydia cases: 505.9 per 100K people (83 cases)
- Gonorrhea cases: 121.9 per 100K people (20 cases)
- Syphilis cases (non-congenital): 6.1 per 100K people (1 case)
--- Primary and secondary syphilis: 6.1 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 0 cases
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#12. Madison County

- Chlamydia cases: 526.8 per 100K people (689 cases)
- Gonorrhea cases: 208.0 per 100K people (272 cases)
- Syphilis cases (non-congenital): 18.4 per 100K people (24 cases)
--- Primary and secondary syphilis: 12.2 per 100K people (16 cases)
--- Nonprimary and nonsecondary early syphilis: 6.1 per 100K people (8 cases)
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#11. Tippecanoe County

- Chlamydia cases: 539.9 per 100K people (1,010 cases)
- Gonorrhea cases: 195.6 per 100K people (366 cases)
- Syphilis cases (non-congenital): 27.8 per 100K people (52 cases)
--- Primary and secondary syphilis: 17.1 per 100K people (32 cases)
--- Nonprimary and nonsecondary early syphilis: 10.7 per 100K people (20 cases)
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#10. Vigo County

- Chlamydia cases: 577.4 per 100K people (612 cases)
- Gonorrhea cases: 315.1 per 100K people (334 cases)
- Syphilis cases (non-congenital): 13.2 per 100K people (14 cases)
--- Primary and secondary syphilis: 4.7 per 100K people (5 cases)
--- Nonprimary and nonsecondary early syphilis: 8.5 per 100K people (9 cases)
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#9. Delaware County

- Chlamydia cases: 579.2 per 100K people (648 cases)
- Gonorrhea cases: 245.8 per 100K people (275 cases)
- Syphilis cases (non-congenital): 9.8 per 100K people (11 case)
--- Primary and secondary syphilis: 7.2 per 100K people (8 cases)
--- Nonprimary and nonsecondary early syphilis: 2.7 per 100K people (3 cases)
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#8. Lake County

- Chlamydia cases: 581.7 per 100K people (2,900 cases)
- Gonorrhea cases: 237.5 per 100K people (1,184 cases)
- Syphilis cases (non-congenital): 16.6 per 100K people (83 cases)
--- Primary and secondary syphilis: 11.4 per 100K people (57 cases)
--- Nonprimary and nonsecondary early syphilis: 5.2 per 100K people (26 cases)
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#7. Allen County

- Chlamydia cases: 582.8 per 100K people (2,265 cases)
- Gonorrhea cases: 225.7 per 100K people (877 cases)
- Syphilis cases (non-congenital): 7.5 per 100K people (29 cases)
--- Primary and secondary syphilis: 2.3 per 100K people (9 cases)
--- Nonprimary and nonsecondary early syphilis: 5.1 per 100K people (20 cases)
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#6. Monroe County

- Chlamydia cases: 589.1 per 100K people (824 cases)
- Gonorrhea cases: 181.6 per 100K people (254 cases)
- Syphilis cases (non-congenital): 7.9 per 100K people (11 case)
--- Primary and secondary syphilis: 2.1 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 5.7 per 100K people (8 cases)
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#5. Grant County

- Chlamydia cases: 590.1 per 100K people (391 case)
- Gonorrhea cases: 265.6 per 100K people (176 cases)
- Syphilis cases (non-congenital): 9.1 per 100K people (6 cases)
--- Primary and secondary syphilis: 4.5 per 100K people (3 cases)
--- Nonprimary and nonsecondary early syphilis: 4.5 per 100K people (3 cases)
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#4. Howard County

- Chlamydia cases: 608.2 per 100K people (509 cases)
- Gonorrhea cases: 264.1 per 100K people (221 case)
- Syphilis cases (non-congenital): 2.4 per 100K people (2 cases)
--- Primary and secondary syphilis: 1.2 per 100K people (1 case)
--- Nonprimary and nonsecondary early syphilis: 1.2 per 100K people (1 case)
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#3. Vanderburgh County

- Chlamydia cases: 718.9 per 100K people (1,294 cases)
- Gonorrhea cases: 429.5 per 100K people (773 cases)
- Syphilis cases (non-congenital): 43.3 per 100K people (78 cases)
--- Primary and secondary syphilis: 28.3 per 100K people (51 case)
--- Nonprimary and nonsecondary early syphilis: 15.0 per 100K people (27 cases)
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#2. St. Joseph County

- Chlamydia cases: 732.1 per 100K people (1,993 cases)
- Gonorrhea cases: 356.0 per 100K people (969 cases)
- Syphilis cases (non-congenital): 14.0 per 100K people (38 cases)
--- Primary and secondary syphilis: 5.9 per 100K people (16 cases)
--- Nonprimary and nonsecondary early syphilis: 8.1 per 100K people (22 cases)
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#1. Marion County

- Chlamydia cases: 1,102.7 per 100K people (10,708 cases)
- Gonorrhea cases: 539.9 per 100K people (5,243 cases)
- Syphilis cases (non-congenital): 70.5 per 100K people (685 cases)
--- Primary and secondary syphilis: 34.8 per 100K people (338 cases)
--- Nonprimary and nonsecondary early syphilis: 35.7 per 100K people (347 cases)

This story features data reporting and writing by Emma Rubin and is part of a series utilizing data automation across 49 states.

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