What are the common Sexually Transmitted Infections (STIs)?

Common Sexually Transmitted Infections (STIs)

The most common sexually transmitted infections include chlamydia, gonorrhea, trichomoniasis, syphilis, herpes simplex virus, human papillomavirus (HPV), hepatitis B, hepatitis C, and HIV. 1, 2

Bacterial STIs

Chlamydia

• Caused by Chlamydia trachomatis
• Highest prevalence among adolescents and young adults
• Often asymptomatic (especially in women)
• Can cause cervicitis, urethritis, proctitis, and pharyngitis
• Complications include pelvic inflammatory disease (PID), tubal infertility, ectopic pregnancy, and chronic pelvic pain 2
• Treatment: Doxycycline 100 mg orally twice daily for 7 days 1

Gonorrhea

• Caused by Neisseria gonorrhoeae
• Highest rates among 15-19 year olds 2
• Can cause urethritis, cervicitis, pharyngitis, and proctitis
• May be asymptomatic, especially in women
• Treatment: Ceftriaxone 125-250 mg IM single dose PLUS doxycycline 100 mg orally twice daily for 7 days 1

Syphilis

• Caused by Treponema pallidum
• Presents in stages: primary (chancre), secondary (rash), latent, and tertiary
• Increasing incidence in recent years 3
• Treatment varies by stage:
  • Primary/secondary/early latent: Benzathine penicillin G 2.4 million units IM single dose
  • Late latent/unknown duration: Benzathine penicillin G 2.4 million units IM weekly for 3 weeks 1

Trichomoniasis

• Caused by Trichomonas vaginalis (protozoan parasite)
• Often asymptomatic in men; women may have vaginal discharge
• Treatment: Metronidazole 2g orally in a single dose 1

Viral STIs

Human Papillomavirus (HPV)

• Most common STI in the United States 3
• Can cause genital warts and certain cancers (cervical, anal, penile)
• Often asymptomatic
• Treatment focuses on removing visible warts using:
  • Patient-applied: podofilox 0.5% solution/gel or imiquimod 5% cream
  • Provider-administered: cryotherapy, surgical removal, or trichloroacetic acid 1

Herpes Simplex Virus (HSV)

• Causes genital herpes
• HSV-1 and HSV-2 can both cause genital infections
• Presents as painful vesicles or ulcers
• No cure, but antiviral medications can manage symptoms and reduce transmission 4

Hepatitis B and C

• Can be transmitted sexually
• May lead to chronic liver disease and hepatocellular carcinoma
• Hepatitis B vaccine available for prevention 1

HIV

• Causes AIDS if untreated
• Transmitted through sexual contact, blood, or from mother to child
• Early detection and antiretroviral therapy are essential 1

Other STIs

Pubic Lice ("Crabs")

• Caused by Pthirus pubis
• Treatment: Permethrin 1% creme rinse or pyrethrins with piperonyl butoxide 1

Scabies

• Caused by the mite Sarcoptes scabiei
• Characterized by intense itching and rash
• Treatment: Permethrin 5% cream 1

Epidemiology and Risk Factors

• Approximately 19 million new STIs occur annually in the United States 2
• Highest rates among adolescents and young adults
• Significant racial disparities exist, with higher rates among non-Hispanic African Americans 2
• Risk factors include:
  • Multiple sexual partners
  • Inconsistent condom use
  • Previous STI history
  • Substance use during sexual activity

Prevention Strategies

• Consistent and correct condom use
• Regular screening for at-risk individuals
• Vaccination (available for HPV and hepatitis B)
• Partner notification and treatment
• Abstinence or mutual monogamy with uninfected partner 1

Common Pitfalls in STI Management

1. Relying on symptoms alone for diagnosis

   • Many STIs are asymptomatic, especially in women
   • Regular screening is essential for at-risk populations 1

2. Failing to test for co-infections

   • STIs often occur together
   • Test for multiple infections when one is detected 1

3. Inadequate partner treatment

   • Untreated partners can lead to reinfection
   • Partner notification and treatment are crucial 1

4. Incomplete therapy

   • Full course of treatment is necessary even if symptoms resolve
   • Single-dose therapy may improve compliance for some infections 5

Remember that early detection and treatment of STIs are essential to prevent complications and reduce transmission to others. Regular screening is recommended for sexually active individuals, especially adolescents and young adults.