What is the primary mode of hepatitis C transmission?

Primary Mode of Hepatitis C Transmission

The primary mode of hepatitis C virus (HCV) transmission is parenteral exposure to blood, with injection drug use being the most common route of transmission in developed countries, accounting for 60-80% of new HCV infections. 1

Routes of HCV Transmission

Parenteral Transmission (Most Common)

• Injection Drug Use:

  • 50-100% of intravenous drug users (IVDU) test positive for anti-HCV 1
  • Currently accounts for approximately 60-80% of new HCV infections in developed countries 1, 2
  • Sharing of contaminated needles and injection equipment is the primary risk factor

• Other Parenteral Routes:

  • Blood transfusion and blood products: Historically significant but now rare in countries with blood donor screening (risk <1 in 200,000 in England) 1
  • Needlestick injuries: Risk estimated at 1.8% (0-7%) globally and 0.92% in South Korea 1
  • Organ transplantation from infected donors 1
  • Hemodialysis 1
  • Tattooing, piercing, acupuncture with non-sterilized equipment 1
  • Unsafe medical procedures: Including surgery, endoscopy, and dental treatments without proper disinfection (particularly in developing countries) 1

Sexual Transmission (Less Common)

• Generally considered inefficient compared to bloodborne routes 1
• Risk factors that increase likelihood of sexual transmission:
  • Multiple sexual partners 1
  • HIV co-infection 1
  • Traumatic sexual practices or sex accompanying wounds 1
  • Presence of other sexually transmitted infections 1
  • Homosexual men with HIV have higher rates (11.7%) than those without HIV history 1
• Risk in long-term monogamous relationships is low (<5%) 1

Vertical (Mother-to-Child) Transmission

• Overall risk: 1-6.2% 1
• Higher risk factors:
  • Maternal HIV co-infection (increases risk to 14-17%) 1
  • High maternal HCV RNA levels 1
  • Female infants 1
• Breastfeeding is generally safe unless nipples are cracked or bleeding 1
• Cesarean section does not prevent transmission 1

Other Potential Routes

• Household contact: Sharing personal items that may be contaminated with blood (razors, toothbrushes) 1
• HCV has been detected in saliva in some studies 1

Prevention Strategies

• No effective vaccine is currently available 1
• Key prevention measures include:
  1. Screening of blood, organ, and tissue donors 1
  2. Harm reduction for injection drug users (needle exchange programs, substance abuse treatment) 3
  3. Standard precautions in healthcare settings 1
  4. Proper sterilization of equipment for tattooing, piercing, and acupuncture 1
  5. Education about risk factors and transmission routes 1
  6. HCV-infected persons should not share personal items that might have blood on them 1

Important Caveats

• In approximately 10% of cases, no identifiable risk factor can be determined 2
• The relative importance of transmission routes varies by geographic region and population 1
• Patients should be counseled that the effect of treatment on HCV transmission is not fully established 4, 5
• Routine screening is recommended for all adults born between 1945-1965 and those with risk factors 6