RISK FACTORS

Current risks in the United States:

• 60% - IV drug use.

• <20% - sexual transmission (infected partner/multiple partners.)

• 10% - occupational, household, perinatal and dialysis.)

• 10% - no recognized source.

The risk factors for HCV infection differ some what from hepatitis B and HIV. There is a big variation in prevalence of HCV infection among persons with different risk factors and characteristics.

Highest Risk – Persons with large or repeated direct percutaneous exposures to blood e.g. injection drug users and those receiving transfusion of infected blood and blood products.

Moderate Risk – Persons with frequent but smaller direct percutaneous exposures e.g. long-term hemodialysis patients.

Lower Risk – Persons with inapparent percutaneous or mucosal exposures e.g. those with high-risk sexual practices or persons with small, sporadic percutaneous exposures like health-care workers.

Lowest Risk – Persons with no risk factors e.g. volunteer blood donors.

IV & Other Drug Abuse

At present IV drug abuse is the major risk factor for HCV infection and has been the most common cause (60%) of newly acquired HCV infections during the past 10 years in the United States. Although the number of acute infections with hepatitis C has declined dramatically since 1989, the incidence and prevalence remains high in this group.

The risk of getting infected with hepatitis C due to intravenous injection drug use is much higher than getting infected with HIV or HBV. 

About 60–90% of injection drug users have HCV infection, which is four times more common than HIV and therefore there is a greater risk of getting exposed to an HCV infected individual through IV drug use as compared to risk of exposure to HIV or HBV.

Hepatitis C is more rapidly acquired after initiation of injection drug use as compared to other viral infections and one study reported 50–90% of users became infected within a year.  

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Why test for HCV?

Identification of HCV infected persons by screening tests is important as it provides them with the opportunity for

Evaluation for chronic liver disease and possible treatment before irreversible damage has occurred

Counseling to avoid potential liver toxins such as alcohol that may increase the severity of their disease

Counseling how to reduce the risk of transmitting this disease to others

Counseling on changing the high-risk behaviors and avoid getting other disease

Assessment of Risk

As part of a complete medical history for all patients, it is important to obtain a history of high-risk behaviors associated with transmission of HCV in addition to other blood borne pathogens. Patients should be routinely questioned about risk factors for viral hepatitis. The most important role that health care providers can play is identifying these asymptomatic individuals belonging to the high-risk groups who should be offered screening for hepatitis C infection and other diseases. Screening should always be accompanied by counseling and medical follow up. 

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Testing Definitely Recommended: 

Only high-risk groups based on their risk for infection and include persons with selected medical conditions, e.g. recipients of transfusions or organ transplants, including:

Recipients of an organ transplant before July 1992.

Recipients of blood transfusion or blood components before July 1992.

Recipients of blood who were notified their donor later tested positive for HCV infection.

Persons who ever used injection drugs including those who infrequently indulged in recreational drug use many years ago.

Recipients of clotting factor concentrates before 1987.

Chronic hemo-dialysis patients.

Persons with persistently abnormal ALT (alanine aminotransferase levels.)

Persons who should also be tested as they are at high-risk based on a recognized exposure include:

Infants no younger than 12 months old born to women with HCV infection and

Health care, emergency medical and public safety workers after needle sticks, sharps or mucosal exposures to HCV positive blood.

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Testing Definitely NOT Recommended in United States because they have no risk factor:

Health-Care, Emergency Medical, and Public Safety Workers - Routine testing is recommended only for follow-up for a specific exposure.

Pregnant Women - take risk histories and test only if at risk.

The general population.

Household (Nonsexual) Contacts of HCV-positive persons, unless a history exists of a direct (percutaneous or mucosal) exposure to blood.

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Testing is of uncertain Need in the following persons from other risk groups as the overall prevalence of HCV among these persons is low or unknown. (although higher risk in other countries):

Recipients of transplated tissue (e.g., corneal, musculoskeletal, skin, ova, sperm).

Intranasal cocaine and other noninjecting illegal drug users. (Hepatitis C infection has also been associated with history of intranasal cocaine use, however hepatitis C patients rarely report it in the absence of other risk factors.)

Persons with a history of tattooing or body piercing.

Persons with a history of multiple sex partners or sexually transmitted diseases.

Long-term steady sex partners of HCV-positive persons.

Even individuals with a previous history of only limited and occasional experimental use are considered at high risk for HCV infection and need to be screened even if the exposure was 20-30 years ago.

Transfusion of Blood and Blood Products

Since 1992 HCV has rarely been transmitted by blood transfusion.

Effective inactivation procedures for preparing clotting factor concentrates were introduced in 1985 and 87, reducing the transmission very significantly in persons with hemophilia.

During May 1990, routine testing of donors for evidence of HCV infection was initiated and  later in July 1992, more sensitive multi-antigen testing was implemented. With these new improved screening practices and policies for blood and blood products (including clotting factors concentrates, albumin and immune globulin) the incidence of post-transfusion hepatitis C has markedly decreased, reducing the risk for transmission of HCV infection to 0.001% per unit of blood transfused.

Organ Tissue Transplants

As with blood donor screening the risk of HCV transmission has been virtually eliminated with the use of the same screening and policy changes mentioned before for blood and blood products.

Sexual Transmission

The transmission of hepatitis C through sexual activity is controversial. Recent data indicate 10–20% of hepatitis is transmitted sexually. Among acute hepatitis C patients reported to the CDC during the past five years, 15% had a history of unprotected sexual exposure as a source of their infection in the absence of percutaneous exposure to HCV and two third's had a partner who was found to be hepatitis C positive.

Current data indicates that between long-term steady partners in a monogamous relationship, transmission is rare although not absent.

Among persons with multiple partners the risk of acquiring HCV infection is higher and has been associated with other sexually transmitted diseases and failure to use condoms.

Household Contacts (non-sexual)

This is very rare but theoretically possible if exposure to infectious blood occurs.

Perinatal Transmission

The prevalence of HCV among pregnant women in the United States is about 1% and risk of transmission of this infection during pregnancy from the HCV infected mother to the infant is about 5%. Factors that have been associated with increased transmission of the virus include:

Maternal co-infection with HIV.

Higher maternal HCV titers (although no thresholds are known).

Breast feeding is not associated with HCV transmission (as compared to HIV). The HCV virus has not been found in human milk and although the data is limited, the overall incidence between breast-fed and bottle-fed infants is the same.

Occupational Exposure

Although the overall prevalence is low, health care workers are also at-risk of acquiring HCV infection primarily as a result of percutaneous exposures to blood. The risk of transmission after an accidental needle stick contaminated with HCV infected blood has averaged 2 percent. There is one case report of transmission after a splash to the eye.

Percutaneous Exposure

In other countries there is a risk of HCV with tattooing, body piercing and commercial barbering. In the United States no such associations have been proved, however, more studies are needed to determine the risk with these types of exposures and the settings in which they occur such as unregulated commercial establishments.

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