Hepatitis C transmission: Routes and risks

Hepatitis C is a blood-borne virus that poses a significant public health threat in Canada. Despite substantial advances in hepatitis C testing and treatment, one reason many people remain undiagnosed is a lack of understanding of how the virus is transmitted. Understanding hepatitis C transmission routes and the factors that influence risk is critical to engage individuals in testing and prevention approaches. This article outlines hepatitis C transmission routes, including shared drug use equipment, unsterilized tattoo and piercing equipment, sexual and vertical transmission, unsafe medical procedures or traditional healing practices and sharing personal care items, along with the factors that contribute to the transmission risk for each of these routes.

How is hepatitis C transmitted?

Hepatitis C is transmitted primarily through blood-to-blood contact. While the hepatitis C virus has also been found in other bodily fluids (e.g., rectal fluid, semen, vaginal and menstrual fluid, saliva and breastmilk), the risk of transmission through these fluids is minimal to nonexistent.^1–5

Once someone is exposed to the hepatitis C virus, primarily through blood, the virus can enter the bloodstream and cause an infection. Hepatitis C is highly transmissible because only trace amounts of blood are required to transmit the virus and it can also sometimes persist outside the body for several days or, in some cases (e.g., inside a syringe), for many weeks. These factors increase the chance of transmission. 

In Canada, the primary population affected by hepatitis C has shifted over time from individuals who received unscreened blood products to people who share drug use equipment. However, hepatitis C transmission also needs to be considered in the global context, especially among immigrants and newcomers to Canada who may have been exposed to the virus through other routes in their home countries. Immigrants and newcomers are not screened for hepatitis C upon arrival in Canada, leaving people undiagnosed. 

Hepatitis C is mainly transmitted through blood-to-blood contact; any activity involving such contact poses a high risk of transmission. That said, the actual risk of transmission depends on the context of the exposure and the prevalence of hepatitis C in the population. Understanding the various transmission routes and the levels of risk associated with each helps to identify the unique factors that may put someone at risk for hepatitis C. 

By which transmission routes can hepatitis C be passed?

Sharing drug use equipment

The most significant hepatitis C transmission route in Canada is the sharing of equipment used to inject drugs (e.g., needles, syringes, cookers, filters). Sharing syringes, needles and other equipment used to prepare the drugs for injection can lead to direct blood-to-blood contact, resulting in a high risk of hepatitis C transmission.^6–9 For example, research shows that sharing needles carries a transmission risk ranging from 0.25%¹⁰ to 0.57%⁸ from a single instance of injection drug use. 

Sharing equipment used to smoke or snort drugs (e.g., pipes and straws) also carries a risk of hepatitis C transmission in Canada. While the exact transmission risk per sharing event for non-injection methods is less well defined, hepatitis C has been detected on equipment used to smoke and snort drugs (e.g., straws, pipes).¹¹ In addition, evidence shows that sharing equipment used to smoke or snort drugs is associated with an increased risk for hepatitis C.^12–14 

Several factors can influence the risk of hepatitis C transmission for people who use drugs (PWUD) in Canada. One key factor is the already high prevalence of hepatitis C within this population.¹⁵ With a higher prevalence of hepatitis C in the community, there is a higher likelihood of being exposed to hepatitis C when sharing equipment to use drugs.⁷ Another factor is how frequently a person shares drug use equipment; the more often a person shares, the more likely they are to be exposed to the virus, increasing their risk for hepatitis C. Risk is also influenced by inconsistent access to harm reduction supplies within communities¹⁶ and by social and structural barriers (e.g., criminalization),^17,18 which can make it challenging for PWUD to obtain and use new equipment. 

Unsterilized tattoo and piercing equipment

Tattooing and piercing can transmit hepatitis C because of the potential for blood-to-blood contact, but the risk depends on the context. In professional tattoo and piercing studios, when proper infection control practices are used, there is no risk of hepatitis C transmission.¹⁹ This is because using sterile or new equipment for tattoos and piercings eliminates the risk of transmission.¹⁹ Professional tattoo and piercing studios in Canada are required to implement infection control practices, including sterilizing equipment (e.g., needles and cartridges) or using single-use equipment (e.g., ink).²⁰ 

In an unregulated setting, where no infection control practices are used, there is a risk for hepatitis C transmission from tattooing and piercing.¹⁹ However, the exact transmission risk is not known because of a lack of research establishing the per act transmission risk when no infection control practices are used. One of the main unregulated settings is the prison environment, where these activities frequently occur without proper infection control practices.^19,21,22 A factor that increases the risk of hepatitis C transmission in this environment is the high prevalence of hepatitis C among people who are incarcerated.²¹ Another factor that increases the risk is a lack of access to sterile equipment and single-use equipment in unregulated settings.^23,24 

Sexual transmission

Although the exact mechanisms for the sexual transmission of hepatitis C are not fully understood, it is considered an uncommon mode of transmission. However, research suggests that some biological and behavioural factors increase sexual transmission risk by facilitating blood-to-blood contact, especially in certain populations. Most studies on sexual hepatitis C transmission have primarily focused on gay and bisexual men and other men who have sex with men (gbMSM), among whom sexual transmission of hepatitis C happens more frequently.^25–28 Among heterosexual monogamous couples, transmission is rare.^3,29,30 Heterosexual people with multiple partners face higher risks, which may be due to behavioural factors like engaging in higher risk sex or increased exposure to sexually transmitted and blood-borne infections (STBBIs).^3,30 

Research shows that co-infection with HIV and the presence of pre-existing STBBIs (e.g., syphilis) are two biological factors linked to sexual hepatitis C transmission for both heterosexual and gbMSM populations.^3,25,27,30 While it is unclear exactly what mechanisms are responsible for increasing the risk for sexually acquired hepatitis C among people living with HIV, several theories have been proposed. Hepatitis C virus has been found more frequently in the semen of gbMSM co-infected with HIV and hepatitis C, potentially increasing the risk for sexual transmission.^27,31 HIV is also more easily transmitted through sexual contact than hepatitis C, so gbMSM having unprotected sex may actually be acquiring HIV first.³² Evidence about the role of immune suppression from HIV is mixed,²⁶ but breakdown of the mucous membranes of a person living with HIV may make it easier for the hepatitis C virus to enter the bloodstream during sex.^27,31 Similarly, pre-existing STBBIs that cause ulcers or sores, such as syphilis, may also increase the risk of sexual hepatitis C transmission by making it easier for the virus to enter the body.^25,27,30 

Several behavioural factors have been found to contribute to the risk for sexual hepatitis C transmission among gbMSM. Some activities that may expose someone to the virus include having condomless anal sex, using drugs before or during sex, having sex where blood may be present (e.g., rough or prolonged sex, fisting) or having group sex.^25–27 A factor that increases the risk of hepatitis C transmission is how often someone engages in activities where they may be exposed to the virus. These factors play a larger role in the risk for sexual transmission among some gbMSM populations, but sexual activities that have potential for blood-to-blood contact (i.e., condomless anal sex) may still contribute to transmission risk for heterosexual couples.³ Among some gbMSM, factors like using drugs during sex make it difficult to determine the exact drivers of sexual transmission risk. Drug use during sex can lead to disinhibition, increasing high-risk sexual behaviours, but people who use drugs during sex may also be more likely to share drug use equipment.²⁵

Vertical transmission

Vertical transmission, where hepatitis C is passed from parent to child during pregnancy or childbirth, is not a common transmission route in Canada. The results of a systematic review indicated that vertical transmission happens in up to 8% of infants born to a person with an active hepatitis C infection (i.e., a person who has not been treated or spontaneously cleared the virus).³³ While having a higher viral load (i.e., more than 600 copies of the virus/mL) increases the risk of transmission, the exact transmission risk associated with different viral loads is unknown.^33,34 For pregnant people living with HIV, the transmission risk is even higher, ranging from 11%³⁵ to 12% of infants.³⁶ Vertical transmission can happen during both pregnancy and delivery, but the mode of delivery does not significantly impact transmission.³⁷ There is no evidence to suggest that hepatitis C can be passed from parent to child while breastfeeding or chestfeeding.^38,39 Canadian research suggests that while the overall hepatitis C prevalence among pregnant people is low,⁴⁰ women of reproductive age are an emerging priority population for hepatitis C prevention and care on the basis of their increased representation in populations impacted by hepatitis C (e.g., people who use drugs).^40,41 Because of this, vertical transmission may become more common in Canada and warrants ongoing attention. 

Unsafe medical procedures and traditional healing practices

Medical procedures, blood transfusions and traditional healing practices (e.g., acupuncture and wet cupping) can potentially transmit hepatitis C when there is blood-to-blood contact, but the level of risk depends on the context. In Canada, the risk associated with these interventions is low to nonexistent because of strict infection control practices.³⁷ Equipment used in medical settings is either sterilized after each use (e.g., surgical tools) or intended for single use only (e.g., acupuncture needles, syringes). 

Routine blood screening, which was introduced in 1992,⁴² has eliminated the risk of hepatitis C transmission from blood transfusions in Canada. Only those who received transfusions before 1992 in Canada are at risk for hepatitis C.⁴³ Hepatitis C can be transmitted through needlestick injuries in healthcare settings;⁴⁴ however, the risk is low because of the use of personal protective equipment and protocols for safe handling of biohazardous materials like needles.^44,45

Although the risk of hepatitis C transmission from medical interventions (e.g., injections, surgical procedures) is low to non-existent in Canada, the risk can be higher in other countries. Immigrants and newcomers to Canada may have been exposed to the virus before their arrival through medical or traditional healing procedures in regions where infection control practices are limited. Individuals travelling to such regions for medical or traditional healing procedures may also be exposed to hepatitis C. In countries lacking adequate blood or blood product screening there is an increased risk of transmission.^37,46 Additionally, the reuse of medical equipment without proper sterilization remains common in some countries, increasing the risk of transmission from medical procedures.^37,46

Traditional healing practices such as acupuncture and wet cupping that involve skin penetration and potential blood-to-blood contact also carry a risk of hepatitis C transmission if infection control practices are lacking. Undergoing traditional healing practices in regulated settings is associated with little to no risk, as the equipment and needles used are either single-use or sterilized. As with other medical interventions, a lack of proper sterilization and infection control practices increases the risk for hepatitis C transmission.^47–49 

Sharing personal care items

The sharing of personal care items that can cause small cuts or retain traces of blood (e.g., razors, scissors, nail clippers, toothbrush) is not a common transmission route for hepatitis C,^50,51 although there is a risk of transmission when personal care equipment is not properly sterilized between uses (e.g., in barbershops and salons).^52,53 Despite limited evidence about the exact transmission risk, research shows that transmission from personal care items is most likely to happen within families⁵⁴ if someone in the family has an active hepatitis C infection. 

Implications for service providers

Understanding the main hepatitis C transmission routes and their associated risk factors can help service providers more effectively screen and engage individuals in care, as well as provide more tailored resources to support prevention efforts. While individual risk factors play a role in hepatitis C transmission, a person’s risk is impacted by more than their behaviours. Social and structural factors, like financial and housing instability or the criminalization of drug use, can shape a person’s hepatitis C transmission risk. Some communities (e.g., PWUD, gbMSM) are disproportionately impacted by hepatitis C. Being a member of these communities is not a risk factor for hepatitis C; rather, social and structural factors create inequities that impact social determinants of health (i.e., housing, poverty) and access to healthcare. The impact of these inequities can also limit a person’s ability to manage their risk. Recognizing how risk is created and reinforced by these social and structural factors can help service providers better support their clients. 

Some considerations include the following:

• Increasing awareness of transmission routes and risks: Service providers can provide tailored education and support to individuals to promote safer behaviours and regular testing on the basis of individual risk factors. This includes promoting safer drug use and sex practices, as well as encouraging individuals to receive tattoos, piercings or other medical interventions in regulated settings. Presenting or discussing risk factors in a nonjudgmental way empowers people to share their experiences without fear of stigma. Service providers can provide culturally sensitive education and care to immigrant and newcomer populations by recognizing that transmission risks may be different for these communities.
• Encouraging access to prevention resources and supplies: By identifying possible transmission routes, service providers can encourage and guide individuals to access prevention resources, such as new drug use equipment or condoms. Service providers can also encourage people to avoid sharing personal care items when there is known risk for hepatitis C transmission.
• Offering hepatitis C screening and linkage to care: People at risk for hepatitis C should be offered testing by a healthcare provider and linked to treatment if they are diagnosed with chronic hepatitis C. One-time testing for hepatitis C could also be considered for individuals who may not otherwise present for regular screening but could benefit from early detection and treatment. Ensuring prenatal screening is offered when appropriate and facilitating referrals to care is also critical to reduce vertical transmission risks and improve health outcomes for parents and children.
• Advocating for accessible and culturally sensitive care: Where appropriate, service providers can advocate for more accessible and culturally safe hepatitis C testing and treatment options, particularly in high-risk settings like correctional facilities, shelters and harm reduction sites, or in community settings for immigrants and newcomers.

References

1. Lohiya GS, Tan-Figueroa L, Lohiya S et al. Human bites: bloodborne pathogen risk and postexposure follow-up algorithm. Journal of the National Medical Association. 2013;105(1):92-5.  
2. Foster AL, Gaisa MM, Hijdra RM et al. Shedding of hepatitis C virus into the rectum of HIV-infected men who have sex with men. Clinical Infectious Diseases. 2017 Feb 1;64(3):284-8. 
3. Terrault NA. Sexual activity as a risk factor for hepatitis C. Hepatology. 2002 Nov 1;36(5 Suppl 1):S99-105. 
4. Wang CC, Cook L, Tapia KA et al. Cervicovaginal shedding of hepatitis C viral RNA is associated with the presence of menstrual or other blood in cervicovaginal fluids. Journal of Clinical Virology. 2011 Jan 1;50(1):4-7.
5. Kage M, Ogasawara S, Kosai KI et al. Hepatitis C virus RNA present in saliva but absent in breast-milk of the hepatitis C carrier mother. Journal of Gastroenterology and Hepatology. 1997 Jul 1;12(7):518-21. 
6. Hagan H, Thiede H, Weiss NS et al. Sharing of drug preparation equipment as a risk factor for hepatitis C. American Journal of Public Health. 2001;91(1):42-6. 
7. Pouget ER, Hagan H, Des Jarlais DC. Meta-analysis of hepatitis C seroconversion in relation to shared syringes and drug preparation equipment. Addiction. 2012 Jun;107(6):1057-65. 
8. Boelen L, Teutsch S, Wilson DP et al. Per-event probability of hepatitis C infection during sharing of injecting equipment. PLOS ONE. 2014 Jul 7;9(7):e100749. 
9. Palmateer N, Hutchinson S, McAllister G et al. Risk of transmission associated with sharing drug injecting paraphernalia: analysis of recent hepatitis C virus (HCV) infection using cross-sectional survey data. Journal of Viral Hepatitis. 2014 Jan 1;21(1):25-32. 
10. Leyva Y, Page K, Shiboski S et al. Per-contact infectivity of hepatitis C virus acquisition in association with receptive needle sharing exposures in a prospective cohort of young adult people who inject drugs in San Francisco, California. Open Forum Infectious Diseases. 2020;7(4):ofaa092.  
11. Aaron S, McMahon JM, Milano D et al. Intranasal transmission of hepatitis C virus: virological and clinical evidence. Clinical Infectious Diseases. 2008 Oct 1;47(7):931-4. 
12. Tortu S, McMahon JM, Pouget ER et al. Sharing of non-injection drug-use implements as a risk factor for hepatitis C. Substance Use & Misuse. 2004;39(2):211-24. 
13. Macías J, Palacios RB, Claro E et al. High prevalence of hepatitis C virus infection among noninjecting drug users: association with sharing the inhalation implements of crack. Liver International. 2008 Jul 1;28(6):781-6. 
14. Scheinmann R, Hagan H, Lelutiu-Weinberger C et al. Non-injection drug use and hepatitis C virus: a systematic review. Drug and Alcohol Dependence. 2007 Jun 6;89(1):1-12. 
15. Degenhardt L, Peacock A, Colledge S et al. Global prevalence of injecting drug use and sociodemographic characteristics and prevalence of HIV, HBV, and HCV in people who inject drugs: a multistage systematic review. The Lancet Global Health. 2017 Dec 1;5(12):e1192-207.
16. Jacka B, Larney S, Degenhardt L et al. Prevalence of injecting drug use and coverage of interventions to prevent HIV and hepatitis C virus infection among people who inject drugs in Canada. American Journal of Public Health. 2020 Dec 4;110(1):45-50. 
17. Argento E, Shannon K, Fairbairn N et al. Increasing trends and incidence of nonfatal overdose among women sex workers who use drugs in British Columbia: the role of criminalization-related barriers to harm reduction. Drug and Alcohol Dependence. 2023 Mar 1;244:109789.
18. Boyd J, Maher L, Austin T et al. Mothers who use drugs: closing the gaps in harm reduction response amidst the dual epidemics of overdose and violence in a Canadian urban setting. American Journal of Public Health. 2022;112(S2):S191-8.
19. Tohme RA, Holmberg SD. Transmission of hepatitis C virus infection through tattooing and piercing: a critical review. Clinical Infectious Diseases. 2012 Apr 15;54(8):1167-78. 
20. Health Canada. Infection prevention and control practices for personal services: tattooing, ear/body piercing, and electrolysis. Canada Communicable Disease Report. 1999;25S3. Available from: https://publications.gc.ca/collections/collection_2016/aspc-phac/HP3-1-25-S3-eng.pdf
21. Poulin C, Courtemanche Y, Serhir B et al. Tattooing in prison: a risk factor for HCV infection among inmates in the Quebec’s provincial correctional system. Annals of Epidemiology. 2018 Apr 1;28(4):231-5.
22. Hellard ME, Aitken CK, Hocking JS. Tattooing in prisons—not such a pretty picture. American Journal of Infection Control. 2007 Sep 1;35(7):477-80.
23. Kondro W. Prison tattoo program wasn’t given enough time. CMAJ. 2007 Jan 30;176(3):307-8. 
24. Bouzanis K, Joshi S, Lokker C et al. Health programmes and services addressing the prevention and management of infectious diseases in people who inject drugs in Canada: a systematic integrative review. BMJ Open. 2021 Sep 1;11(9):e047511. 
25. Lockart I, Matthews GV, Danta M. Sexually transmitted hepatitis C infection: the evolving epidemic in HIV-positive and HIV-negative MSM. Current Opinion in Infectious Diseases. 2019 Feb 1;32(1):31-7.
26. Nijmeijer BM, Koopsen J, Schinkel J et al. Sexually transmitted hepatitis C virus infections: current trends, and recent advances in understanding the spread in men who have sex with men. Journal of the International AIDS Society. 2019;22(Suppl 6):e25348. 
27. Chan DPC, Sun HY, Wong HTH et al. Sexually acquired hepatitis C virus infection: a review. International Journal of Infectious Diseases. 2016 Aug 1;49:47-58. 
28. Jin F, Matthews GV, Grulich AE. Sexual transmission of hepatitis C virus among gay and bisexual men: a systematic review. Sexual Health. 2016 Oct 7;14(1):28-41. 
29. Dodge JL, Terrault NA. Sexual transmission of hepatitis C: a rare event among heterosexual couples. Journal of Coagulation Disorders. 2014 Mar;4(1):38-9. 
30. Tohme RA, Holmberg SD. Is sexual contact a major mode of hepatitis C virus transmission? Hepatology. 2010 Oct 1;52(4):1497-505. 
31. Page EE, Nelson M. Hepatitis C and sex. Clinical Medicine. 2016 Apr 1;16(2):189-92.
32. Price JC, Mckinney JE, Crouch PC et al. Sexually acquired hepatitis C infection in HIV-uninfected men who have sex with men using preexposure prophylaxis against HIV. Journal of Infectious Diseases. 2019 Apr 16;219(9):1373-6. 
33. Deng S, Zhong W, Chen W et al. Hepatitis C viral load and mother-to-child transmission: a systematic review and meta-analysis. Journal of Gastroenterology and Hepatology. 2023 Feb 1;38(2):177-86. 
34. Prasad M, Saade GR, Clifton RG et al. Risk factors for perinatal transmission of hepatitis C virus. Obstetrics and Gynecology. 2023 Sep 1;142(3):449-56. 
35. Benova L, Mohamoud YA, Calvert C et al. Editor’s choice: vertical transmission of hepatitis C virus: systematic review and meta-analysis. Clinical Infectious Diseases. 2014 Sep 9;59(6):765-73.  
36. Ades AE, Gordon F, Scott K et al. Overall vertical transmission of hepatitis C virus, transmission net of clearance, and timing of transmission. Clinical Infectious Diseases. 2023 Mar 3;76(5):905-12. 
37. Stroffolini T, Stroffolini G. Prevalence and modes of transmission of hepatitis C virus infection: a historical worldwide review. Viruses. 2024 Jul 1;16(7):1115. 
38. Yeung CY, Lee HC, Chan WT et al. Vertical transmission of hepatitis C virus: current knowledge and perspectives. World Journal of Hepatology. 2014 Sep 9;6(9):643-51. 
39. Cottrell EB, Chou R, Wasson N et al. Reducing risk for mother-to-infant transmission of hepatitis C virus: a systematic review for the U.S. preventive services task force. Annals of Internal Medicine. 2013;158(2):109-13.
40. Biondi MJ, Lynch K, Floriancic N et al. Evaluation of prenatal hepatitis C virus prevalence using universal screening, and linkage to care in a real-world setting in Ontario. Journal of Obstetrics and Gynaecology Canada. 2024 Jun 1;46(6):102423.
41. Pearce ME, Bartlett SR, Yu A et al. Women in the 2019 hepatitis C cascade of care: findings from the British Columbia Hepatitis Testers cohort study. BMC Women’s Health. 2021 Dec 1;21(1):1-15. 
42. Gabarin N, Yan M. Chapter 1. Vein to vein: a summary of the blood system in Canada. In: Transfusion: clinical guide. Ottawa: Canadian Blood Services; 2024 Oct 16 [cited Jan 23 2025]. Available from: https://professionaleducation.blood.ca/en/transfusion/clinical-guide/vein-vein-summary-blood-system-canada
43. Ha S, Totten S, Pogany L et al. Hepatitis C in Canada and the importance of risk-based screening. Canada Communicable Disease Report. 2016 Mar 3;42(3):57-62.
44. Garozzo A, Falzone L, Rapisarda V et al. The risk of HCV infection among health-care workers and its association with extrahepatic manifestations. Molecular Medicine Reports. 2017;15(5):3336-9.
45. Tarigan LH, Cifuentes M, Quinn M et al. Prevention of needle-stick injuries in healthcare facilities: a meta-analysis. Infection Control & Hospital Epidemiology. 2015;36(7):823-9. 
46. Thursz M, Fontanet A. HCV transmission in industrialized countries and resource-constrained areas. Nature Reviews Gastroenterology & Hepatology. 2013 Oct 1;11(1):28-35. 
47. Hyun MH, Kim JH, Jang JW et al. Risk of hepatitis C virus transmission through acupuncture: a systematic review and meta-analysis. Korean Journal of Gastroenterology. 2023 Sep 25;82(3):127-36. 
48. El-Ghitany EM, Abdel Wahab MM, Abd El-Wahab EW et al. A comprehensive hepatitis C virus risk factors meta-analysis (1989–2013); Do they differ in Egypt? Liver International. 2015 Feb 1;35(2):489-501. 
49. Madani TA. Hepatitis C virus infections reported in Saudi Arabia over 11 years of surveillance. Annals of Saudi Medicine. 2007;27(3):191-4. 
50. Lock G, Dirscherl M, Obermeier F et al. Hepatitis C – contamination of toothbrushes: myth or reality? Journal of Viral Hepatitis. 2006 Sep 1;13(9):571-3. 
51. Tumminelli F, Marcellin P, Rizzo S et al. Shaving as potential source of hepatitis C virus infection. The Lancet. 1995 Mar 11;345(8950):658.
52. Bashir HH, Kamani L, Usman M et al. Awareness and safe practices of hepatitis B and C prevention and transmission among workers of women beauty salons. Pakistan Journal of Medical Sciences. 2022 Nov 1;38(8):2156-62. 
53. Bari A, Akhtar S, Rahbar MH et al. Risk factors for hepatitis C virus infection in male adults in Rawalpindi–Islamabad, Pakistan. Tropical Medicine & International Health. 2001 Sep 1;6(9):732-8. 
54. Sherief LM, Beshir MR, Salem GM et al. Intrafamilial transmission of hepatitis C virus among families of infected pediatric oncology patients. Pediatric Infectious Disease Journal. 2019 Jul 1;38(7):692-7. 

Externally reviewed by: Davis Baskin & Dr. Curtis Cooper

About the author(s)

Madison Kennedy is CATIE's knowledge specialist in hepatitis C. She has a Master of Public Health degree in Health Promotion and previously worked in sexual and reproductive health service delivery and research.