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Hepatitis C

What Healthcare Providers Need to Know

Our courses fulfill continuing nursing education requirements in all 50 states. For more accreditation information, click here. Nurse practitioners may apply these contact hours to pharmacy continuing education and prescriptive authorization.

Unless otherwise cited, the material in this course is based on a report of the Centers for Disease Control and Prevention entitled The Recommendations for Prevention and Control of Hepatitis C Virus (HCV) Infection and HCV-Related Chronic Disease. The full text is available from http://www.cdc.gov/mmwr/preview/mmwrhtml/00055154.htm.

Post test and learning objectives were prepared by Sharon Sanders, RN.

Hepatitis C virus (HCV) infection is the most common chronic blood-borne infection in the United States. During the 1980s an average of 242,000 new infections occurred each year. Since 1989 the annual number of new infections had declined by more than 80% to 36,000 by 1996. An estimated 3.9 million (1.8%) Americans have been infected with HCV. Most of these individuals are chronically infected and may not be aware of their infection because they are not clinically ill. Infected individuals serve as a source of transmission to others and are at risk for chronic liver disease or other HCV-related chronic diseases during the first two or more decades following initial infection.

Chronic liver disease is the tenth leading cause of death among adults in the United States; it accounts for approximately 25,000 deaths annually, or approximately 1% of all deaths. Because most HCV-infected individuals are ages 30 to 49 years, the number of deaths attributable to HCV-related chronic liver disease could increase substantially during the next ten to twenty years as this group of infected individuals reaches ages at which complications from chronic liver disease typically occur.

HCV is transmitted primarily through large or repeated direct percutaneous exposures to blood. Blood transfusion, which accounted for a substantial proportion of HCV infections acquired more than fifteen years ago, rarely accounts for recently acquired infections. Since 1994 risk for transfusion-transmitted HCV infection has been so low that CDC's sentinel counties' viral hepatitis surveillance system has been unable to detect any transfusion-associated cases of acute hepatitis C, although the risk is not zero. In contrast, injection drug use has consistently accounted for a substantial proportion of HCV infections and currently accounts for 60% of HCV transmission in the United States.

DEMOGRAPHIC CHARACTERISTICS

HCV infection occurs among individuals of all ages, but the highest incidence rate (the rate of new cases over a defined period) of acute hepatitis C is found among individuals aged 20 to 39 years, and males predominate. African Americans and whites have similar incidence rates of acute disease; individuals of Hispanic ethnicity have higher rates.

In the general population, the highest prevalence rates (the number of all old and new cases during a defined period) of HCV infection are found among individuals aged 30 to 49 years, and among males. Unlike the racial/ethnic pattern of acute disease, African Americans have a substantially higher prevalence of chronic HCV infection than do whites.

PREVALENCE OF HCV

The greatest variation in prevalence of HCV infection occurs among individuals with different risk factors for infection. The highest prevalence of infection is found among those with large or repeated direct percutaneous exposures to blood (eg, individuals with hemophilia treated with clotting factor concentrates produced before 1987, injection drug users, and recipients of transfusions from HCV-positive donors).

Moderate prevalence is found among those with frequent but smaller direct percutaneous exposures (eg, long-term hemodialysis clients). Lower prevalence of HCV infection is found among those with inapparent percutaneous or mucosal exposures (eg, healthcare workers). Lowest prevalence of HCV infection is found among those with no high-risk characteristics (eg, volunteer blood donors). The estimated prevalence of individuals with differing risk factors and characteristics also varies widely in the United States population.

TRANSMISSION MODES

Risk factors associated with transmission of HCV in the United States were identified in case-control studies conducted during 1978–86. These risk factors included blood transfusion, injection drug use, employment in client care or clinical laboratory work, exposure to a sex partner or household member who has a history of hepatitis, exposure to multiple sex partners, and low socioeconomic level. These studies reported no association with military service or exposures resulting from medical, surgical, or dental procedures, tattooing, acupuncture, ear piercing, or foreign travel. If transmission from such exposures does occur, the frequency is apparently too low to detect.

HCV is rarely transmitted by blood transfusion. During 1985–90, cases of transfusion-associated non-A, non-B hepatitis declined by more than 50% because of screening policies that excluded donors with human immunodeficiency virus (HIV) infection and donors with surrogate markers for non-A, non-B hepatitis.

Current risk for transfusion-associated hepatitis C is 1/100,000 per unit transfused.

Receipt of clotting factor concentrates prepared from plasma pools posed a high risk for HCV infection until effective procedures to inactivate viruses, including HCV, were introduced during 1985 (Factor VIII) and 1987 (Factor IX). Individuals with hemophilia who were treated with products before inactivation of those products have prevalence rates of HCV infection as high as 90%.

Transplantation of organs from infectious donors to the organ recipient also carried a high risk for transmitting HCV infection before donor screening. Limited studies of recipients of transplanted tissue have implicated transmission of HCV only from nonirradiated bone tissue of unscreened donors. As with blood donor screening, use of anti-HCV (antibody to hepatitis C virus) negative organ and tissue donors has virtually eliminated risks for HCV transmission from transplantation.

Injection and Other Illegal Drug Use

Although the number of cases of acute hepatitis C among injection drug users has declined dramatically since 1989, both incidence and prevalence of HCV infection remain high in this group. Injection drug use currently accounts for most HCV transmission in the United States. HCV infection is acquired more rapidly through injection than other viral infections. The rates of HCV infection among young injection drug users are four times higher than rates of HIV infection. After five years of injecting, as many as 90% of users are infected with HCV.

HCV infection has been independently associated with a history of intranasal cocaine use although, among clients with acute hepatitis C identified in CDC's sentinel counties' viral hepatitis surveillance system since 1991, intranasal cocaine use in the absence of injection drug use was uncommon. Thus, at least in the recent past, intranasal cocaine use rarely appears to have contributed to transmission.

Nosocomial and Occupational Exposures

Nosocomial transmission of HCV is possible if infection-control techniques or disinfection procedures are inadequate and contaminated equipment is shared among clients. Such transmission rarely has been reported in the United States, other than in chronic hemodialysis settings. Prevalence of anti-HCV positivity among chronic hemodialysis clients averages 10%, with some centers reporting rates greater than 60%.

Healthcare, EMT, and public safety workers who have exposure to blood in the workplace are at risk for being infected with blood-borne pathogens. However, prevalence of HCV infection among healthcare workers, including orthopedic, general, and oral surgeons, is no greater than the general population.

Percutaneous Exposures in Other Settings

In other countries, HCV infection has been associated with folk medicine practices, tattooing, body piercing, and commercial barbering. However, in the United States, case-control studies have reported no association between HCV infection and these types of exposures. In addition, of clients with acute hepatitis C who were identified in the CDC's sentinel counties' viral hepatitis surveillance system during the past fifteen years and who denied a history of injection drug use, only 1% reported a history of tattooing or ear piercing, and none reported a history of acupuncture. Among injection drug users, frequency of tattooing and ear piercing also was uncommon (3%).

Sexual Activity

Case-control studies have reported an association between exposure to a sex contact with a history of hepatitis or exposure to multiple sex partners and acquiring hepatitis C. In addition, 15% to 20% of clients with acute hepatitis C who have been reported to CDC's sentinel counties' surveillance system have a history of sexual exposure in the absence of other risk factors. Two-thirds of these have an anti-HCV–positive sex partner, and one-third reported more than two partners in the 6 months before illness.

In contrast, a low prevalence of HCV infection has been reported by studies of long-term spouses of clients with chronic HCV infection who had no other risk factors for infection. Only one study has documented an association between HCV infection and MSM (men who have sex with men) activity and, at least in STD clinic settings, the prevalence rate of HCV infection among MSM generally has been similar to that of heterosexuals. Although considerable inconsistencies exist among studies, data indicate overall that sexual transmission of HCV appears to occur, but that the virus is inefficiently spread through this manner.

Household Contact

Case-control studies also have reported an association between nonsexual household contact and acquiring hepatitis C. The presumed mechanism of transmission is direct or inapparent percutaneous or permucosal exposure to infectious blood or body fluids containing blood.

Perinatal Contact

The average rate of HCV infection among infants born to HCV-positive, HIV-negative women is 5% to 6%. The average infection rate for infants born to women co-infected with HCV and HIV is higher at 14%. Studies of HCV/HIV–co-infected women more consistently have indicated an association between virus titer and the transmission of HCV.

The transmission of HCV infection through breast milk has not been documented. In the studies that have evaluated breastfeeding in infants born to HCV-infected women, the average rate of infection was 4% in both breastfed and bottle-fed infants.

Breast feeding is not contraindicated for HCV-positive mothers.

Individuals with No Recognized Source of Infection

Recent studies have demonstrated that injection drug use currently accounts for 60% of HCV transmission in the United States. Although the role of sexual activity in the transmission of HCV remains unclear, more than 20% of individuals with HCV infection report sexual exposures in the absence of percutaneous risk factors. Other known exposures together account for approximately 10% of infections. Thus, a potential risk factor can be identified for approximately 90% of individuals with HCV infection. In the remaining 10%, no recognized source of infection can be identified, although most individuals in this category are associated with low socioeconomic level.

SCREENING AND DIAGNOSTIC TESTS

Serologic Assays

The only tests currently approved by the Food and Drug Administration (FDA) for diagnosis of HCV infection are those that measure anti-HCV. These tests detect anti-HCV in greater than 97% of infected clients, but do not distinguish between acute, chronic, and resolved infection. As with any screening test, positive predictive value of the enzyme immunoassay (EIA) for anti-HCV varies depending on the prevalence of infection in the population, and is low in populations with an HCV infection prevalence of less than 10%.

Supplemental testing with a more specific assay (eg, recombinant strip immunoblot assay [RIBA]) of a specimen with a positive EIA result prevents reporting of false-positive results, particularly in settings where asymptomatic individuals are being tested.

Nucleic Acid (RNA) Detection

The diagnosis of HCV infection also is possible by qualitatively detecting HCV RNA using gene amplification techniques (eg, RT-PCR). HCV RNA can be detected in serum or plasma within 1 to 2 weeks after exposure to the virus and weeks before the onset of ALT elevations or the appearance of anti-HCV.

Although not FDA-approved, RT-PCR assays for HCV infection are used commonly in clinical practice. With adequate optimization of RT-PCR assays, 75% to 85% of individuals who are anti-HCV–positive and more than 95% of individuals with acute or chronic hepatitis C will test positive for HCV RNA. Some HCV-infected individuals might be only intermittently HCV RNA positive, particularly those with acute hepatitis C or with endstage liver disease caused by hepatitis C.

Quantitative assays for measuring the concentration (titer) of HCV RNA have been developed and are available from commercial laboratories, including a quantitative RT-PCR (Amplicor HCV Monitor) and a branched DNA (deoxyribonucleic acid) signal amplification assay (Quanti Plex HCV RNA Assay [bDNA]). These assays also are not FDA-approved, and compared with qualitative RT-PCR assays, are less sensitive. In addition, they each use a different standard, which precludes direct comparisons between them. Quantitative assays cannot be used as a primary test to confirm or exclude the diagnosis of HCV infection or to monitor the endpoint of treatment.

At least six different genotypes (genetic makeup of an organism or virus) and more than 90 subtypes of HCV exist. Approximately 70% of HCV-infected individuals in the United States are infected with genotype 1, with frequency of subtype 1a predominating over subtype 1b. Different nucleic acid detection methods are available commercially to group isolates of HCV, based on genotypes and subtypes. Once the genotype is identified, it need not be tested again; genotypes do not change during the course of infection.

CLINICAL FEATURES AND NATURAL HISTORY

Acute HCV Infection

Individuals with acute HCV infection typically are either asymptomatic or have a mild clinical illness; 60% to 70% have no discernible symptoms; 20% to 30% might have jaundice; and 10% to 20% might have nonspecific symptoms (eg, anorexia, malaise, abdominal pain). In more than 20% of these clients, onset of symptoms might precede anti-HCV seroconversion.

The course of acute hepatitis C is variable, although elevations in serum ALT levels, often in a fluctuating pattern, are its most characteristic feature. Normalization of ALT levels might occur and suggests full recovery, but this is frequently followed by ALT elevations that indicate progression to chronic disease. Fulminant hepatic failure following acute hepatitis C is rare.

Chronic HCV Infection

After acute infection, 15% to 25% of individuals appear to resolve their infection without sequelae, as defined by the sustained absence of HCV RNA in serum and normalization of ALT levels. Chronic HCV infection develops in 75% to 85% of those with persistent or fluctuating ALT elevations, indicating active liver disease developing in 60% to 70% of chronically infected individuals. In the remaining 30% to 40% of chronically infected individuals, ALT levels are normal. A single ALT determination cannot be used to exclude ongoing hepatic injury, and long-term follow-up of clients with HCV infection is required to determine their clinical outcome or prognosis.

The course of chronic liver disease is usually insidious, progressing at a slow rate without symptoms or physical signs in the majority of clients during the first two or more decades after infection. Frequently, chronic hepatitis C is not recognized until asymptomatic individuals are identified as HCV-positive during blood donor screening, or elevated ALT levels are detected during routine physical examinations.

Most studies have reported that cirrhosis develops in 10% to 20% of individuals with chronic hepatitis C over a period of twenty to thirty years, and HCC in 1% to 5%, with striking geographic variations in rates of this disease. However, when cirrhosis is established, the rate of development of HCC might be as high as 1% to 4% per year. In contrast, a study of more than 200 women seventeen years after they received HCV-contaminated RH factor IG reported that only 2.4% had evidence of cirrhosis and none had died.

Although factors predicting severity of liver disease have not been well defined, recent data indicate that increased alcohol intake, being more than 40 years of age at time of infection, and being male are associated with more severe liver disease. In particular, among individuals with alcoholic liver disease and HCV infection, liver disease progresses more rapidly; among those with cirrhosis, a higher risk for development of HCC exists. Furthermore, even intake of moderate amounts of alcohol in clients with chronic hepatitis C might enhance disease progression.

Clinical Management and Treatment

HCV-positive clients need to be evaluated for the presence and severity of chronic liver disease. Initial evaluation for presence of disease should include multiple measurements of ALT at regular intervals, because ALT activity fluctuates in individuals with chronic hepatitis C. Clients with chronic hepatitis C are be evaluated for the severity of their liver disease and for possible treatment.

Antiviral therapy is recommended for clients with chronic hepatitis C who are at greatest risk for progression to cirrhosis. These individuals include anti-HCV–positive clients with persistently elevated ALT levels, detectable HCV RNA, and a liver biopsy that indicates either portal or bridging fibrosis or at least moderate degrees of inflammation and necrosis.

In clients with less severe histologic changes, indications for treatment are less clear, and careful clinical follow-up might be an acceptable alternative to treatment with antiviral therapy (eg, interferon) because progression to cirrhosis is likely to be slow, if it occurs at all. Similarly, clients with compensated cirrhosis (ie, without jaundice, ascites, variceal hemorrhage, or encephalopathy) might not benefit from interferon therapy. Careful assessment should be made and the risks and benefits of therapy thoroughly discussed with the client. Clients with persistently normal ALT values must not be treated outside of clinical trials, as treatment might actually induce liver enzyme abnormalities.

Therapy for hepatitis C is a rapidly changing area of clinical practice. Combination therapy with interferon and ribavirin, a nucleoside analogue, is approved for the naive treatment of clients with chronic hepatitis C. Studies of clients treated with a combination of ribavirin and interferon have demonstrated a substantial increase in sustained response rates, reaching 40% to 50%, compared with response rates of 15% to 25% with interferon alone. However, as with interferon alone, combination therapy in clients with genotype 1 is not as successful, and sustained response rates among these clients are still less than 30%.

Knowing the genotype or serotype (genotype-specific antibodies) of HCV is helpful in making recommendations and counseling regarding therapy. Patients with genotypes 2 and 3 are almost three times more likely than patients with genotype 1 to respond to therapy with interferon or the combination of interferon and ribavirin. When using combination therapy, the recommended duration of treatment depends on the genotype. For patients with genotypes 2 and 3, a 24-week course of combination treatment is adequate, whereas for patients with genotype 1, a 48-week course is recommended (CDC, 2006).

Other treatments, including corticosteroids, ursodiol, and thymosin, have not been effective. High iron levels in the liver might reduce the efficacy of interferon. Use of iron-reduction therapy (phlebotomy or chelation) in combination with interferon has been studied, but results have been inconclusive. Clients are becoming more interested in alternative therapies (eg, traditional Chinese medicine, antioxidants, naturopathy, homeopathy) and physicians must be prepared to address questions regarding these topics.

Post Exposure

Immune globulin (IG) is not effective for post exposure.

Immune globulin (IG) and antiviral agents are not recommended after exposure to HCV-positive blood. In addition, no guidelines exist for administration of therapy during the acute phase of HCV infection. However, limited data indicate that antiviral therapy might be beneficial when started early in the course of HCV infection. When HCV infection is identified early, the person should be referred for medical management to a specialist knowledgeable in this area (MMWR, 2001).

Prevention and Control Recommendations

Reducing the burden of HCV infection and HCV-related disease in the United States requires implementation of primary prevention activities that reduce risks for contracting HCV infection, and secondary prevention activities that reduce risks for liver and other chronic diseases in HCV-infected individuals.

Primary prevention activities can reduce or eliminate potential risk for HCV transmission from (a) blood, blood components, and plasma derivatives; (b) such high-risk activities as injection drug use and sex with multiple partners; and (c) percutaneous exposures to blood in healthcare and other (ie, tattooing, body piercing) settings. Immunization is not available; therefore, identifying individuals at risk but not infected with HCV provides opportunity for counseling on how to reduce their risk for becoming infected.

Secondary prevention activities can reduce risks of chronic disease by identifying HCV-infected individuals through diagnostic testing and by providing appropriate medical management and antiviral therapy.

Counseling and testing can prevent disease transmission and progression through reducing high-risk practices (eg, injection drug use, alcohol intake). However, the degree to which individuals will change their high-risk practices based on knowing their test results is not known, and possible adverse consequences of testing exist, including disclosure of test results to others that might result in disrupted personal relationships and possible discriminatory action (eg, loss of employment, insurance, educational opportunities). Antiviral treatment is also available, and treatment guidelines have been developed. Such treatment is beneficial for many clients, although sustained response rates and mode of delivery are currently less than ideal.

Individuals at risk for HCV infection who receive healthcare services in the public and private sectors should have access to counseling and testing. Facilities that provide counseling and testing should include services or referrals for medical evaluation and management of individuals identified as infected with HCV. Priorities for implementing new counseling and testing programs should be based on providing access to individuals who are most likely to be infected or who practice high-risk behaviors.

PRIMARY PREVENTION RECOMMENDATIONS

Blood, Plasma, Organs, Tissues, and Semen

Current practices that exclude blood, plasma derivatives, organ, tissue, or semen donors determined to be at increased risk for HCV by history or who have serologic markers for HCV infection must be maintained to prevent HCV transmission from transfusions and transplants.

High-Risk Drug and Sexual Practices

Healthcare professionals in all settings should routinely obtain a history that inquires about use of illegal drugs and evidence of high-risk sexual practices. Primary prevention of illegal drug injecting will eliminate the greatest risk factor for HCV infection in the United States. Individuals who inject drugs or who are at risk for STDs need to be counseled regarding what they can do to minimize their risk for becoming infected or of transmitting infectious agents to others, including need for vaccination against hepatitis B. Injecting and noninjecting illegal drug users and sexually active men who have sex with men (MSM) also should be vaccinated against hepatitis A.

Based on the findings of multiple studies, syringe- and needle-exchange programs can be an effective part of a comprehensive strategy to reduce the incidence of blood-borne virus transmission and do not encourage the use of illegal drugs.

PERCUTANEOUS EXPOSURES TO BLOOD

Healthcare Settings

Healthcare, emergency medical, and public safety workers need to be educated regarding risk for and prevention of blood-borne infections, including the need to be vaccinated against hepatitis B. Standard barrier precautions and engineering controls must be implemented to prevent exposure to blood.

Healthcare professionals responsible for overseeing clients receiving home infusion therapy must ensure that clients and their families (or caregivers) are informed of potential risk for infection with blood-borne pathogens. Clients and families are given training with a standardized curriculum that includes appropriate infection-control procedures, and these procedures are evaluated regularly through home visits.

Currently, no recommendations exist to restrict professional activities of healthcare workers with HCV infection. As recommended for all healthcare workers, those who are HCV-positive must follow strict aseptic technique and Standard Precautions, including appropriate use of hand washing, protective barriers, and care in the use and disposal of needles and other sharp instruments.

In chronic hemodialysis settings, intensive efforts must be made to educate new staff and re-educate existing staff regarding hemodialysis-specific infection-control practices that prevent the transmission of HCV and other blood-borne pathogens. Hemodialysis center precautions are more stringent than Standard Precautions.

Standard Precautions require use of gloves only when touching blood, body fluids, secretions, excretions, or contaminated items. In contrast, hemodialysis center precautions require glove use whenever clients or hemodialysis equipment is touched. Standard Precautions do not restrict use of supplies, instruments, and medications to a single client; hemodialysis center precautions specify that none of these items be shared among any clients.

Other Settings

Individuals who are considering tattooing or body piercing should be informed of potential risks of acquiring infection with blood-borne and other pathogens through these procedures. These procedures might be a source of infection if equipment is not sterile or if the artist or piercer does not follow other proper infection-control procedures.

SECONDARY PREVENTION RECOMMENDATIONS

Testing is to be offered routinely to individuals most likely to be infected with HCV who might require medical management, and testing needs to be accompanied by appropriate counseling and medical follow-up.

As part of a complete medical history for all clients, it is important to obtain a history of high-risk exposures associated with HCV and other blood-borne pathogens. Such a history can be used to identify asymptomatic individuals who ought to be offered testing for HCV infection. Routine testing is currently recommended only for individuals who belong to groups with a known high prevalence of infection:

• Individuals who have ever injected illegal drugs
• Individuals with selected medical conditions such as hemophilia, long-term hemodialysis clients, persistently abnormal ALT levels, and individuals with evidence of liver disease
• Prior recipients of blood transfusions or organ transplants

Percutaneous or Permucosal Exposures to Blood

Individual institutions should establish policies and procedures for HCV testing of individuals after percutaneous or permucosal exposures to blood and ensure that all personnel are familiar with these policies and procedures.

Children Born To HCV-Positive Women

Because of their recognized exposure, children born to HCV-positive women should be tested for HCV infection. If positive for either anti-HCV or HCV RNA, children should be evaluated for the presence or development of liver disease, and those children with persistently elevated ALT levels must be referred to a specialist for medical management.

TESTING RECOMMENDATIONS

For the following individuals, routine testing for HCV infection is not recommended unless they have risk factors for infection:

• Healthcare, emergency medical, and public safety workers
• Pregnant women
• Household (nonsexual) contacts of HCV-positive individuals
• The general population

For individuals at potential (or unknown) risk for HCV infection, the need for, or effectiveness of, routine testing has not been determined:

• Recipients of transplanted tissue (eg, corneal, musculoskeletal, skin, ova, sperm)
• Intranasal cocaine and other noninjecting illegal drug users
• Individuals with a history of tattooing or body piercing
• Individuals with a history of multiple sex partners or sexually transmitted diseases
• Long-term steady sex partners of HCV-positive individuals

HCV-positive individuals with long-term steady partners do not need to change their sexual practices. Individuals with HCV infection should discuss with their partner the need for counseling and testing. If the partner chooses to be tested and tests negative, the couple should be informed of available data regarding risk for HCV transmission by sexual activity to assist them in making decisions about precautions. If the partner tests positive, appropriate counseling and evaluation for the presence or development of liver disease is provided.

TESTING FOR HCV INFECTION

Consent for testing should be obtained in a manner consistent with that for other medical care and services provided in the same setting, and should include measures to prevent unwanted disclosure of test results to others.

Comprehensive information regarding hepatitis C is provided before testing; however, this might not be practical when HCV testing is performed as part of a clinical work-up or when testing for anti-HCV is required. In these cases, individuals are informed that

• testing for HCV infection will be performed,
• individual results will be kept confidential, and
• appropriate counseling and referral will be offered if results are positive.

The diagnosis of HCV infection can be made by detecting either anti-HCV or HCV RNA. Anti-HCV for routine testing of asymptomatic individuals includes both EIA to test for anti-HCV and supplemental or confirmatory testing with an additional, more specific assay. Use of supplemental antibody testing (ie, RIBA™) for all positive anti-HCV results by EIA is preferred, particularly in settings where clinical services are not provided directly.

The specificity of the HCV EIA 2.0 and HCV Version 3.0 ELISA is > 99%. However, among a population with a low prevalence of infection, even a specificity of 99% does not provide the desired predictive value for a positive test.

Among immunocompetent populations—volunteer blood donors, active duty and retired military personnel, the general population, healthcare workers, or clients attending STD clinics—with anti-HCV prevalences of less than 10%, the proportion of false-positive results with HCV EIA 2.0, or HCV Version 3.0 ELISA, averages approximately 35%.

Among immunocompromised populations (eg, hemodialysis patients), the proportion of false-positive results averages approximately 15%. For this reason, it is critical not to rely exclusively on positive anti-HCV screening results to determine whether a person has been infected; positive results must be verified with an independent supplemental test having high specificity (MMWR, 2003).

Supplemental anti-HCV testing confirms the presence of anti-HCV (it eliminates false-positive antibody results), which indicates past or current infection and can be performed on the same serum sample collected for the EIA (ie, routine serology). Confirmation or exclusion of HCV infection in a person with indeterminate anti-HCV supplemental test results is made on the basis of further laboratory testing, which might include repeating the anti-HCV in two or more months or testing for HCV RNA and ALT level.

In clinical settings, use of RT-PCR to detect HCV RNA might be appropriate to confirm the diagnosis of HCV infection (eg, in clients with abnormal ALT levels or with indeterminate supplemental anti-HCV test results) although RT-PCR assays are not currently FDA-approved.

Detection of HCV RNA by RT-PCR in a person with an anti-HCV-positive result indicates current infection. However, absence of HCV RNA in a person with an anti-HCV-positive result based on EIA testing alone (without supplemental anti-HCV testing) cannot differentiate between resolved infection and a false-positive anti-HCV test result.

In addition, because some individuals with HCV infection might experience intermittent viremia, the meaning of a single negative HCV RNA result is difficult to interpret, particularly in the absence of additional clinical information. If HCV RNA is used to confirm anti-HCV results, a separate serum sample will need to be collected and handled in a manner suitable for RT-PCR. If the HCV RNA result is negative, supplemental anti-HCV testing is performed so that the anti-HCV EIA result can be interpreted before the result is reported to the client.

Laboratories that perform HCV testing should follow the recommended anti-HCV testing algorithm, which includes use of supplemental testing. Having assurances that the HCV testing is performed in accredited laboratories whose services adhere to recognized standards of good laboratory practice is also necessary. Laboratories that perform HCV RNA testing should routinely review their data regarding internal and external proficiency testing because of great variability in accuracy of HCV RNA testing.

PREVENTION MESSAGES AND MEDICAL EVALUATION

HCV-specific information and prevention messages are provided to infected individuals and individuals at risk by trained personnel in public and private healthcare settings.

Regardless of test results, individuals who use illegal drugs or have high-risk sexual practices or occupations need information regarding how to reduce their risk for acquiring blood-borne and sexually transmitted infections or of potentially transmitting infectious agents to others. If their exposure was in the past, individuals who test negative for HCV should be reassured.

Individuals whose HCV test results are indeterminate should be advised that the result is inconclusive, and they should receive appropriate follow-up testing or referral for further testing.

Individuals who test positive should be provided with information regarding the need for (a) preventing further harm to their liver, (b) reducing risks for transmitting HCV to others, and (c) medical evaluation for chronic liver disease and possible treatment.

SURVEILLANCE

The objectives of conducting surveillance for hepatitis C are to:

• Identify new cases and determine disease incidence and trends
• Determine risk factors for infection and disease transmission patterns
• Estimate disease burden
• Identify infected individuals who can be counseled and referred for medical follow-up

FUTURE DIRECTIONS

To reduce occurrences of chronic HCV infection and its sequelae, prevention of new HCV infections must be the primary objective of public health activities. Achieving this objective will require the integration of HCV prevention and surveillance activities into current public health infrastructure.

In addition, several questions concerning the epidemiology of HCV infection remain, and the answers to those questions could change or modify primary prevention activities. These questions primarily concern the magnitude of the risk attributable to sexual transmission of HCV and to illegal noninjecting drug use.

Identification of the large numbers of individuals in the United States with chronic HCV infection is resource-intensive. The most efficient means to achieve this identification is unknown, because the prevention effectiveness of various implementation strategies has not been evaluated.

However, widespread programs to identify, counsel, and treat HCV-infected individuals, combined with improvements in the efficacy of treatment, are expected to lower substantially the morbidity and mortality from HCV-related chronic liver disease. Monitoring the progress of these activities to determine their effectiveness in achieving a reduction in HCV-related chronic disease is important.

Posted May 8, 2006

Expires July 1, 2008

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