How is hepatitis C virus (HCV) infection transmitted?

Updated: Oct 07, 2019
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: BS Anand, MD  more...
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Answer

Transfusion of blood contaminated with hepatitis C virus (HCV) was once a leading means of HCV transmission. Since 1992, however, the screening of donated blood for HCV antibody sharply reduced the risk of transfusion-associated HCV infection. With the advent of more advanced screening tests for HCV such as polymerase chain reaction (PCR), the risk is considered to be less than 1 per 2 million units transfused. The newer assays have decreased the window after infection to 1-2 weeks.

Persons who inject illicit drugs with nonsterile needles are at the highest risk for HCV infection. In developed countries, most of the new HCV infections are reported in injection drug users (IDUs). The most recent surveys of active IDUs in the United States indicate that approximately one third of young (aged 18–30 years) IDUs are HCV-infected. [16] Older and former IDUs typically have a much higher prevalence (approximately 70%-90%) of HCV infection, attributable to needle sharing during the 1970s and 1980s, before greater understanding of the risks of blood-borne viruses and the implementation of public educational strategies. The additional risk of acquiring hepatitis C infection from noninjection (snorted or smoked) cocaine use is difficult to differentiate from that associated with injection drug use and sex with HCV-infected partners. [16]

Transmission of HCV to healthcare workers may occur via needle-stick injuries or other occupational exposures. Needle-stick injuries in the healthcare setting result in a 3% risk of HCV transmission. According to Rischitelli et al, however, the prevalence of HCV infection among healthcare workers is similar to that of the general population. [17] Nosocomial patient-to-patient transmission may occur by means of a contaminated colonoscope, via dialysis, or during surgery, including organ transplantation before 1992.

HCV may be transmitted via sexual transmission. However, studies of heterosexual couples with discordant serostatus have shown that such transmission is extremely inefficient. [18] A higher rate HCV transmission is noted in men who have sex with men (MSM), particularly those who practice unprotected anal intercourse and have infection with human immunodeficiency virus (HIV). [19]

HCV may also be transmitted via tattooing, sharing razors, and acupuncture. The use of disposable needles for acupuncture, now the standard practice in the United States, should eliminate this transmission route. Maternal-fetal HCV transmission may occur at a rate of approximately 4%–5%. [20] Breastfeeding is not associated with transmission. [21] Casual household contact and contact with the saliva of those infected are inefficient modes of transmission. No risk factors are identified in approximately 10% of cases.


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