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Hepatitis C: An Overview

Prevalence | Incidence | Demographics | Natural History | Transmission
Prevention | HCV Testing | Treatment | What You Need To Know

Transmission

How is hepatitis C being transmitted?

  • Routes of Transmission Pie Chart
  • Injecting Drug Use
    • Accounts for 60 percent of HCV transmission
    • Accounts for two-thirds of new infections
    • Highly efficient mode of transmission
    • Prevalence in injecting drugs using populations is high
    • Rapidly acquired after first injection
Prevalence of HCV and HIV in IDUs
Location
Year
HCV
HIV
Amsterdam
1991
66%
33%
Geneva
1992
80%
32%
Baltimore
1994
90%
25%
Seattle
1999
82%
2%
Rural UK
2000
56%
14%
S. China
2003
71%
17%
Vancouver
2004
44%
19%
  • Studies of Young or New Injectors
    • Baltimore (Thomas, et. al): Reported 80 percent prevalence in subjects acknowledging two years of injection drug use or less.
    • Chicago and Suburbs (Thorpe, et. al):
      • Reported 27 percent prevalence in subjects age 18 to 30
      • Reported 15 percent prevalence in subjects acknowledging two years of injection drug use or less.
  • Studies of Young or New Injectors
    • Seattle (Hagan et. al):
      • Reported 41 percent antibody prevalence in subjects acknowledging drug use for two years or less at time of enrollment.
      • Mean time to seroconversion:
        • 0.6 years for those positive at enrollment
        • 5.4 years for those negative at enrollment who later seroconverted
        • 3.4 years weighted average time to seroconversion
  • Factors Associated with Infection
    • Years of injecting
    • Frequency of injection
    • Being a young/new injecting drug user
    • Sharing syringes
    • Sharing cotton/cookers
    • Backloading
  • Sexual Transmission
    • 15 percent of HCV infection
    • However, sex is an inefficient mode of transmission
    • Long-Term Spouses (CDC)
      • A low prevalence of HCV infection has been reported by studies of long-term spouses of patients with chronic HCV infection who had no other risk factors for infection.
      • Five of these studies have been conducted in the United States, involving 30-85 partners each, in which average prevalence was 1.5% (range: 0% to 4.4%)
  • Long-Term Prospective Study (Vandelli et. al.)
    • Enrolled anti-HCV negative partners of HCV positive individuals.
    • 776 partners completed a ten-year follow-up.
    • Three spouses acquired HCV during follow-up.
    • All had other risk factors and/or follow-up testing showed genotype/strain discordant with that of spouse.
  • Sexual Transmission
    • Risk higher among those with multiple partners and history of sexually transmitted disease
    • Prevalence found to average 5 percent among STD clinic patients with no history of injection drug use.
    • Factors associated with positivity
      • Greater number of sex partners
      • History of STDs
      • Failure to use a condom
  • Transfusion
    • 1990
      • Routine testing of donors was initiated.
      • Risk was approximately 1.5% per recipient or approximately 0.2% per unit transfused.
    • July 1992
      • More sensitive testing was implemented.
      • Reducing risk for infection to 0.001% per unit  transfused.
    • 2005
      • Current risk for transfusion-associated hepatitis C is 1 per 2 million units transfused.
  • Blood Clotting Factor
    • Used to treat individuals with hemophilia.
    • High risk of infection prior to the use of virus inactivation procedures that were introduced in 1985 and 1987.
    • Prevalence is greater than 90 percent in hemophiliacs treated with these products before inactivation.
  • Solid Organ Transplants
  • Occupational
    • Occupational exposure is inefficient.
    • In one study that evaluated risk factors for infection, a history of unintentional needle-stick injury was the only occupational risk factor independently associated with HCV infection.
    • Average incidence 1.8 percent following needle stick from HCV-positive source.
    • Prevalence among health care workers is 1 to 2 percent.
  • Nosocomial Transmission
    • Rarely reported in the United States, other than in chronic hemodialysis settings.
    • Prevalence of anti-HCV positivity among chronic hemodialysis patients averages 10%.
    • Studies have documented an association between anti-HCV positivity and increasing years on dialysis.
    • Most likely due to incorrect implementation of infection-control practices.
  • Perinatal
    • Five percent of infected mothers transmit the virus to their baby.
    • Average rate of transmission is higher in women also infected with HIV – 17 percent.
    • No difference seen between vaginal and cesarean births.
  • Household Transmission
    • Rare but not absent
    • Could occur through percutaneous/mucosal exposure to blood
      • Contaminated equipment for home therapies
      • Theoretically through the sharing of personal items (I.e., toothbrushes, razors)
  • No Known Risk
    • In 10 percent of cases, no known risk is identified.
  • Exposures in Other Settings (CDC)
    • No data or insufficient data to show transmission through:
      • Intranasal cocaine use
      • Tattooing
      • Piercing

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