What high-risk sex practices increase the risk of spreading hepatitis C?

High-Risk Sexual Practices That Increase Hepatitis C Transmission

While sexual transmission of HCV is inefficient compared to blood exposure, specific high-risk sexual practices significantly increase transmission risk, particularly having multiple sexual partners, engaging in traumatic sexual practices that cause mucosal injury, having concurrent sexually transmitted diseases, and failing to use condoms consistently. 1

Key High-Risk Sexual Behaviors

Multiple Sexual Partners

• Having multiple sexual partners is the most consistently identified sexual risk factor for HCV transmission across both heterosexual and MSM populations 1
• The threshold varies by study but includes:
  • More than 2 partners in 6 months for persons with acute hepatitis C 1
  • 5 or more partners per year for blood donors 1
  • 10 or more lifetime partners in the general population 1
• Among high-risk populations (STD clinic patients, sex workers), HCV prevalence averages 6% (range 1-10%) even without injection drug use history 1

Traumatic Sexual Practices (Particularly in MSM)

• Practices that cause mucosal trauma and blood-blood contact carry substantially higher risk 2, 3
• Specific high-risk practices include:
  • Fisting (manual-anal penetration) 2, 4
  • Condomless receptive anal intercourse 5
  • Group sex participation 5
  • Use of sex toys 3
  • Rimming 4
• These practices are especially risky in HIV-positive MSM, who show 4-5 times higher odds of HCV transmission compared to HIV-negative men 3

Concurrent STDs and HIV Coinfection

• Presence of genital ulcerative disease significantly increases HCV transmission risk 3
• History of prior STDs is consistently associated with HCV positivity 1
• HIV-infected individuals, particularly MSM, face dramatically elevated risk:
  • HIV-positive women show 3.3-3.9 times higher risk 3
  • HIV-positive MSM show 4.1-5.7 times higher risk compared to HIV-negative men 3
  • HIV/HCV coinfected partners of hemophiliacs show 3% prevalence versus 1.5% in HIV-negative partners 1

Failure to Use Barrier Protection

• Inconsistent or absent condom use is associated with increased HCV transmission 1
• The CDC guidelines explicitly recommend latex condom use "correctly and every time" to prevent transmission 1

Recreational Drug Use During Sex

• Use of recreational drugs during sexual activity doubles the risk of HCV viremia (adjusted OR 2.14) 5
• This includes "slamming" (injecting drugs during sex), though mucosal contact during sex appears to be the primary transmission route even when injection equipment isn't shared 5

Important Nuances and Caveats

Gender-Specific Transmission Patterns

• Male-to-female transmission appears more efficient than female-to-male transmission 1
• Women with HCV-positive male partners show 10% prevalence versus 3% with negative partners 1
• Men with HCV-positive female partners show only 7% prevalence, similar to those with negative partners (8%) 1

Low Risk in Monogamous Relationships

• Long-term monogamous heterosexual partners face very low transmission risk 1
• Studies of steady spouses show only 1.5% average HCV prevalence (range 0-4.4%) 1
• This low rate has raised questions about whether unacknowledged percutaneous exposures (hidden injection drug use) may explain some apparent sexual transmission cases 1

The MSM Paradox

• Despite sexual transmission of bloodborne viruses typically being more efficient in MSM, HCV rates in MSM are not substantially higher than heterosexuals in most settings 1
• However, a recent epidemic of sexually transmitted HCV specifically among HIV-positive MSM has emerged since 2002, particularly in those on HIV pre-exposure prophylaxis 2
• This suggests that specific high-risk practices within certain MSM subpopulations drive transmission, rather than MSM status alone 6

Clinical Prevention Recommendations

The CDC recommends counseling all at-risk individuals that:

• The surest prevention is sex with only one uninfected partner or abstinence 1
• Latex condoms must be used correctly and consistently 1
• Hepatitis B vaccination is essential for all at-risk individuals 1
• Sexually active MSM should also receive hepatitis A vaccination 1

Healthcare providers should routinely screen for high-risk sexual practices including multiple partners and STD history in all patient care settings 1, as 15-20% of acute hepatitis C cases report only sexual exposure without other risk factors 1.