What are the top 10 sexually transmitted diseases (STDs)?

Top 10 Sexually Transmitted Diseases

The most clinically significant sexually transmitted diseases, prioritized by prevalence, morbidity, and public health impact, include: (1) Chlamydia trachomatis, (2) Human Papillomavirus (HPV), (3) Neisseria gonorrhoeae, (4) Herpes Simplex Virus (HSV-2), (5) Trichomonas vaginalis, (6) HIV, (7) Treponema pallidum (syphilis), (8) Hepatitis B, (9) Hepatitis A, and (10) Haemophilus ducreyi (chancroid). 1, 2, 3

1. Chlamydia trachomatis (Chlamydia)

• Most common bacterial STD in the United States with an estimated 3 million cases annually, with highest rates in adolescent girls (4-15% prevalence in screening studies) 1
• Often asymptomatic in women, leading to untreated pelvic inflammatory disease, infertility, ectopic pregnancy, and chronic pelvic pain in 10-20% of cases 1
• 77% of all chlamydial infections are never symptomatic, making screening the most effective control method 4
• First-line treatment is doxycycline 100 mg orally twice daily for 7 days 5

2. Human Papillomavirus (HPV)

• Most sexually active persons get HPV at some time in their lives, though most will never know it 1
• High-risk HPV types cause cervical cancer and other anogenital cancers, while low-risk types cause genital warts 1
• Vaccine-preventable: HPV vaccines are recommended for girls and young women aged 9-26 years 1, 5
• No clinically validated test exists for men to determine HPV infection status 1

3. Neisseria gonorrhoeae (Gonorrhea)

• Highest rates occur among persons 15-19 years of age 1
• 86% of untreated gonorrhea cases are asymptomatic, emphasizing the need for routine screening 4
• Increases HIV transmission risk twofold to fivefold and increases HIV RNA shedding in semen tenfold 1
• Treatment requires ceftriaxone 125 mg IM plus doxycycline 100 mg orally twice daily for 7 days when both gonorrhea and chlamydia are suspected 5

4. Herpes Simplex Virus Type 2 (Genital Herpes)

• Causes recurrent genital ulcers with no cure; antiviral therapy (acyclovir, valacyclovir, famciclovir) provides clinical benefit but does not eradicate latent virus 1, 5
• Strongly linked to increased HIV transmission risk (twofold to fivefold increase) through genital ulceration 1
• Suppressive antiviral therapy reduces but does not eliminate subclinical viral shedding 1
• Transmission can occur through asymptomatic viral shedding, requiring consistent barrier contraception 5

5. Trichomonas vaginalis (Trichomoniasis)

• Nonulcerative STD that increases HIV transmission risk twofold to fivefold 1
• Wet mount examination should be performed when vaginal discharge or malodor is present 5
• Often presents with vaginal discharge, pruritus, and dysuria in women; frequently asymptomatic in men 2

6. Human Immunodeficiency Virus (HIV)

• STD infection is a sentinel event indicating unprotected sexual activity and increased HIV risk 1
• Other STDs facilitate HIV transmission by increasing both infectiousness (through increased viral shedding) and susceptibility (through mucosal barrier disruption) 1
• Preexposure prophylaxis is an effective prevention measure 5
• Early detection and treatment of other STDs reduces HIV acquisition by 38% 1

7. Treponema pallidum (Syphilis)

• Causes genital ulcers that strongly facilitate HIV transmission (twofold to fivefold increased risk) 1
• If acquired after the neonatal period, almost 100% indicative of sexual contact 1
• Requires evaluation in all patients with acute proctitis following receptive anal intercourse 1
• Can cause serious long-term complications including cardiovascular and neurological disease if untreated 2

8. Hepatitis B Virus (HBV)

• Vaccine-preventable: every person being evaluated or treated for an STD should receive hepatitis B vaccination unless already vaccinated 1, 5
• Transmitted through sexual contact and can cause chronic liver disease, cirrhosis, and hepatocellular carcinoma 6
• Hepatitis B vaccine should be administered for postexposure prophylaxis when indicated 5

9. Hepatitis A Virus (HAV)

• Transmitted primarily by fecal-oral route during sexual activity 1
• Produces self-limited disease with 28-day incubation period; does not cause chronic infection 1
• Some persons (particularly men who have sex with men and injection drug users) should receive hepatitis A vaccination 1
• Overall case-fatality rate is 0.5%, with acute liver failure being rare 1

10. Haemophilus ducreyi (Chancroid)

• Most strongly linked to HIV transmission among ulcerative STDs 1
• Incidence is very low in the United States (only 78 cases reported in 2000), but substantially underdiagnosed 1
• Treated with single-dose azithromycin or ceftriaxone, or multiday regimens of ciprofloxacin or erythromycin 1
• HIV-infected patients may require longer therapy courses and should only receive single-dose regimens if follow-up is ensured 1

Key Clinical Considerations

Screening Priorities

• Nucleic acid amplification tests (NAATs) should be performed from all sites of penetration or attempted penetration with high sensitivity (86.1-100%) and specificity (97.1-100%) 5
• Routine screening of all sexually active women 25 years or younger for chlamydia is essential 1
• Asymptomatic infections are the primary reason STDs remain untreated, making routine screening at high-volume sites the most effective control method 4

Partner Management

• Sexual partners within the preceding month must be examined and treated for confirmed STIs 5
• Partners in long-term relationships tend to share HPV infection 1

Common Pitfalls

• Many STDs are asymptomatic (45% of gonorrhea, 77% of chlamydia), so symptom-based diagnosis misses the majority of cases 4
• Clinically significant acyclovir resistance has not emerged among immunocompetent persons with HSV 1
• HIV infection may alter the natural history of many STDs and response to antimicrobial therapy, requiring close clinical follow-up 1