Vaccine Preventable STDs

The most effective means to prevent transmission of infectious diseases, including STDs, is through preexposure immunization. Vaccines are available for prevention of HAV and HBV, both of which can be transmitted sexually. Vaccines are under development or are undergoing clinical trials for other STDs, including HIV, HPV, and HSV; however, current efforts regarding vaccination focus largely on integrating use of currently available vaccines into STD prevention and treatment activities.

Every person seeking treatment for an STD should be considered a candidate for hepatitis B vaccination, and some persons (e.g., MSM and injection-drug users) should be considered for hepatitis A vaccination. Evaluation for vaccination is most effectively done through a screening and education process that both inquires about risk factors for infection (e.g., sex partners and use of illegal drugs), educates patients about the importance of vaccination, and excludes persons who are not candidates for vaccination (e.g., laboratory confirmed diagnosis of infection and previous vaccination).

Although it is uncommon, patients may present with signs, symptoms, or laboratory findings of acute or chronic viral hepatitis. When this occurs, a precise diagnosis must be made and appropriate clinical services provided, including postexposure immunization of contacts and medical referral.

Hepatitis A

Hepatitis A, caused by infection with HAV, has an incubation period from time of exposure to onset of symptoms of approximately 4 weeks (range: 15--50 days). HAV replicates in the liver and is shed in high concentrations in feces from 2 weeks before to 1 week after the onset of clinical illness. HAV is most commonly transmitted by the fecal-oral route. Although viremia occurs early in infection and can persist for several weeks after onset of symptoms, bloodborne transmission of HAV is uncommon.

HAV infection produces a self-limited disease that does not result in chronic infection or chronic liver disease. However, 10%--15% of patients may experience a relapse of symptoms during the 6 months after acute illness. Acute liver failure from hepatitis A is rare (0.3% overall case-fatality rate), but occurs more frequently in older persons (1.8% case fatality rate in adults >50 years of age) and persons with underlying chronic liver disease. The risk for symptomatic infection is directly related to age, with >80% of adults having symptoms compatible with acute viral hepatitis and most children having either asymptomatic or unrecognized infection. Antibody produced in response to HAV infection persists for life and confers protection against reinfection.

Approximately 33% of the U.S. population has serologic evidence of prior HAV infection, which increases directly with age and reaches 75% among persons aged >70 years. Most cases of hepatitis A result from person-to-person transmission during community-wide outbreaks. The most frequently reported source of infection (12%--26%) is either household or sexual contact with a person who had hepatitis A. In addition, outbreaks regularly occur among users of injection and non-injection drugs and among MSM. In the United States, up to 10% of reported cases of HAV occur among persons reporting these behaviors. Approximately 50% of persons with hepatitis A do not have an identified source for their infection.

Hepatitis A, like other enteric infections, can be transmitted during sexual activity. Recent outbreaks of hepatitis A among MSM have occurred in urban areas in the United States. Although some studies have associated having a greater number of sex partners, frequent oral-anal contact, insertive anal intercourse, or serologic evidence of other STDs with HAV infection, other studies have not found specific risk factors for infection.

Unlike persons with most other STDs, HAV-infected persons are infectious for only a relatively brief period of time. However, many sexual practices facilitate fecal-oral transmission of HAV, and inapparent fecal contamination is commonly present during sexual intercourse. Measures typically used to prevent the transmission of other STDs (e.g., use of condoms) do not prevent HAV transmission, and maintenance of "good personal hygiene" has not been successful in interrupting outbreaks of hepatitis A. Vaccination is the most effective means of preventing HAV transmission among persons at risk for sexual transmission of this virus and among persons who use injection and non-injection illegal drugs, many of whom may seek services in STD clinics.

Diagnosis

The diagnosis of hepatitis A cannot be made on clinical grounds alone and requires serologic testing, which is available commercially. The presence of IgM antibody to HAV is diagnostic of acute HAV infection. A positive test for total anti-HAV indicates immunity to HAV infection but does not differentiate acute from past HAV infection. Tests can be positive after hepatitis A vaccination.

Treatment

Patients with hepatitis A usually require only supportive care, with no restrictions in diet or activity. Hospitalization may be necessary for patients who become dehydrated because of nausea and vomiting and for patients with signs or symptoms of acute liver failure. Medications that might cause liver damage or are metabolized by the liver should be used with caution among persons with HAV.

Prevention

Two products are available for the prevention of hepatitis A: hepatitis A vaccine (Table 2) and immune globulin (IG) for IM administration (2). Inactivated hepatitis A vaccines are prepared from formalin-inactivated, cell-culture-derived HAV and have been available in the United States since 1995 for persons aged >2 years. Administered in a two-dose series, these vaccines induce protective antibody levels in virtually all adults. By 1 month after the first dose, 94%--100% of adults have protective antibody levels; 100% of adults develop protective antibody following a second dose. In randomized controlled trials, the equivalent of one dose of hepatitis A vaccine administered before exposure has been 94%--100% effective in preventing clinical hepatitis A (3). Kinetic models of antibody decline indicate that protective levels of antibody persist for at least 20 years.

A combined hepatitis A and B vaccine has been developed for adults. When administered on a 0-, 1-, 6-month schedule, the vaccine has equivalent immunogenicity to that of the monovalent vaccines.

IG is a sterile solution of concentrated immunoglobulins prepared from pooled human plasma processed by cold ethanol fractionation. In the United States, IG is produced only from plasma that has tested negative for HBV, antibody to HIV, and antibody to HCV. In addition, the manufacturing process must either include a viral inactivation step or the final product must test negative for HCV RNA. When administered before or within 2 weeks after exposure to HAV, IG is >85% effective in preventing hepatitis A.

TABLE 2. Recommended regimens: dose and schedule for hepatitis A vaccines

Preexposure Immunization

Persons in the following groups should be offered hepatitis A vaccine:

• MSM, including those who report having minimal or no current sexual activity;
• illegal drug users (both injection and non-injection drug users); and
• persons with chronic liver disease, including persons with chronic HBV and HCV infection who have evidence of chronic liver disease.

Hepatitis A vaccine currently is available for children and adolescents aged <19 years through the Vaccines for Children (VFC) program (tel: 800-232-2522).

Prevaccination Serologic Testing for Susceptibility

Screening for HAV infection may be cost-effective in populations where the prevalence of infection is likely to be high (e.g., older persons and persons born in areas of high HAV endemicity). The potential cost-savings of testing should be weighed against the likelihood that testing will interfere with initiating vaccination. Vaccination of a person who is already immune is not harmful.

Postvaccination Serologic Testing

Postvaccination serologic testing is not indicated because most persons respond to vaccine. In addition, the commercially available serologic test is not sensitive enough to detect the low, but protective, levels of antibody produced by vaccination.

Postexposure Prophylaxis

Previously unvaccinated persons exposed to HAV (e.g., through household or sexual contact or by sharing illegal drugs with a person who has hepatitis A) should be administered a single IM dose of IG (0.02 mL/kg) as soon as possible, but not >2 weeks after exposure. Persons who have had one dose of hepatitis A vaccine at least 1 month before exposure to HAV do not need IG. If hepatitis A vaccine is recommended for a person receiving IG, it can be administered simultaneously at a separate anatomic injection site. The use of hepatitis A vaccine alone is not recommended for postexposure prophylaxis.

Special Considerations

Limited data indicate that vaccination of HIV-infected persons results in lower seroprotection rates and antibody concentrations (3). Antibody response may be directly related to CD4+ levels.

Hepatitis B

Hepatitis B is caused by infection with HBV. The incubation period from time of exposure to onset of symptoms is 6 weeks to 6 months. HBV is hepatotropic, is found in highest concentrations in the blood, and is found in lower concentrations in other body fluids (e.g., semen, vaginal secretions, and wound exudates). HBV infection can be self-limited or chronic. In adults, only 50% of acute HBV infections are symptomatic, and about 1% of cases result in acute liver failure and death. Risk for chronic infection is associated with age at infection: about 90% of infected infants and 60% of infected children aged <5 years become chronically infected compared with 2%--6% of adults. Among persons with chronic HBV infection, the risk of death from cirrhosis or hepatocellular carcinoma is 15%--25%.

In the United States, an estimated 181,000 persons were infected with HBV in 1998, and about 5,000 deaths occurred from HBV-related cirrhosis or hepatocellular carcinoma. An estimated 1.25 million people are chronically infected with HBV, serve as a reservoir for infection, and are at increased risk for death from chronic liver disease.

HBV is efficiently transmitted by percutaneous or mucous membrane exposure to infectious body fluids. Sexual transmission among adults accounts for most HBV infections in the United States. In the 1990s, transmission among hetero-sexual partners accounted for about 40% of infections, and transmission among MSM accounted for another 15% of infections. The most common risk factors for heterosexual transmission include having multiple sex partners (i.e., more than one partner in a 6-month period) or a recent history of an STD. Risk factors for infection among MSM include having multiple sex partners, engaging in unprotected receptive anal intercourse, and having a history of other STDs. Changes in sexual practices among MSM to prevent HIV infection have resulted in a lower risk for HBV infection than that observed in the late 1970s, when studies found up to 70% prevalence of HBV markers among adult MSM. Recent surveys of young MSM (aged 15--22 years) indicated that 6%--13% of participants had evidence of HBV infection, whereas 3%--27% had evidence of having been immunized against hepatitis B (98).

Among persons with acute hepatitis B, up to 70% have previously received care in settings where they could have been vaccinated (e.g., STD clinics, drug treatment programs, and correctional facilities). A 1997 survey of STD clinics demonstrated that hepatitis B vaccine was routinely offered in only 5% of these settings.

Diagnosis

The diagnosis of acute or chronic HBV infection cannot be made on clinical grounds, but requires serologic testing (Table 3). Hepatitis B surface antigen (HBsAg) is present in either acute or chronic infection. The presence of IgM antibody to hepatitis B core antigen (IgM anti-HBc) is diagnostic of acute HBV infection. Antibody to HBsAg (anti-HBs) is produced following a resolved infection and is the only HBV antibody marker present following immunization. The presence of HBsAg with a negative test for IgM anti-HBc is indicative of chronic HBV infection. The presence of anti-HBc may indicate either acute, resolved, or chronic infection.

TABLE 3. Serologic markers in different stages of hepatitis B virus (HBV) infection

Treatment

Laboratory testing should be used to confirm suspected acute or chronic HBV infection, and infected persons should be referred for medical follow-up and possible treatment of chronic infection. In addition, contacts should be vaccinated (see Exposure to Persons who have Acute Hepatitis B) and receive postexposure prophylaxis. No specific therapy is available for persons with acute HBV infection; treatment is supportive.

Antiviral agents (i.e., alpha-interferon or lamivudine) are available for treatment of persons with chronic hepatitis B. To determine the likelihood of response to treatment, an initial evaluation is required to determine the status of the chronic HBV infection and the extent of liver disease. For this reason, treatment should be offered by health-care professionals with experience in the treatment of hepatitis B.

Prevention

Two products have been approved for hepatitis B prevention: hepatitis B immune globulin (HBIG) and hepatitis B vaccine. HBIG is prepared from plasma known to contain a high titer of anti-HBs and is used for postexposure prophylaxis. The recommended dose of HBIG for children and adults is 0.06 mL/kg. The dose is 0.5 mL to prevent perinatal HBV infection among infants born to HBsAg-positive mothers.

Hepatitis B vaccine uses HBsAg produced in yeast by recombinant DNA technology and provides protection from HBV infection when used for both preexposure immunization and postexposure prophylaxis. The two available monovalent hepatitis B vaccines for use in adolescents and adults are Recombivax HB^® (Merck and Co., Inc.) and Engerix-B (SmithKline Beecham Biologicals).

The recommended vaccine dose varies by product and age of recipient (Table 4). Vaccine should be administered IM in the deltoid muscle and can be administered simultaneously with other vaccines. Many vaccination schedules have been used for both adults and adolescents. A two-dose schedule has been approved for adolescents aged 11--15 years using the adult dose of Recombivax HB^®. If the vaccination series is interrupted after the first or second dose of vaccine, the missed dose should be administered as soon as possible. The series does not need to be restarted if a dose has been missed.

In adolescents and healthy adults aged <40 years, approximately 50% develop a protective antibody response (anti-HBs >10 mIU/mL) after the first vaccine dose, 70% after the second, and >90% after the third dose. Because relatively high rates of protection are achieved following each vaccine dose, hepatitis B vaccination should be initiated even if completion of the series cannot be ensured. Because most fully vaccinated persons have long-lasting protection from HBV infection, periodic testing to determine antibody levels in immune competent persons is not necessary, and booster doses of vaccine are not recommended.

Hepatitis B vaccine has been shown to be safe; more than 20 million adolescents and adults have been vaccinated in the United States. The vaccine is well tolerated by most recipients. Pain at the injection site or low grade fever are reported by a minority of recipients. Anaphylaxis is estimated to occur in one in 600,000 doses of vaccine administered; no deaths have been reported following anaphylaxis. Hepatitis B vaccine has not been associated with multiple sclerosis, diabetes, or other autoimmune or neurologic diseases in any controlled epidemiologic study. Vaccine is contraindicated in persons with a history of anaphylaxis after a previous dose of hepatitis B vaccine and in persons with a known anaphylactic reaction to yeast.

CDC's national immunization strategy to eliminate transmission of HBV infection includes a) prevention of perinatal infection through maternal HBsAg screening and postexposure prophylaxis of at-risk infants, b) universal infant immunization, c) universal immunization of previously unvaccinated adolescents aged 11--12 years (99), and d) vaccination of adolescents and adults at increased risk for infection (100). Although high immunization coverage rates have been achieved among infants and younger adolescents, hepatitis B incidence rates remain high because most infections now occur in adults. Although the cost of vaccine remains a barrier to adult vaccination, vaccine purchase and provider reimbursement should not be a barrier for vaccination of adolescents aged <19 years, who may be eligible for free vaccine under the Vaccines for Children (VFC) program (tel: 800-232-2522).

TABLE 4. Recommended regimen: doses and schedules of currently licensed hepatitis B vaccines for adolescents and adults

Preexposure Immunizations

Hepatitis B vaccine is recommended for all persons who attend STD clinics who have not been previously vaccinated. In the non-STD clinic setting, the following persons should be vaccinated: a) persons with history of an STD, persons who have had multiple sex partners, those who have had sex with an injection-drug user, and sexually active MSM; b) persons engaging in illegal drug use; c) household members, sex partners, and drug-sharing partners of a person with chronic HBV infection; and d) persons on hemodialysis, persons receiving clotting factor concentrates, or persons who have occupational exposure to blood. In addition, hepatitis B vaccine should be offered to all persons who have not been previously vaccinated who receive services in drug treatment programs and long-term correctional facilities.

Prevaccination Antibody Screening

Based on the current cost of hepatitis B vaccine, revaccination serologic testing may be cost-effective in adult populations with a high prevalence of HBV infection (>2% HBsAg positive or >30% anti-HBc positive). However, prevaccination testing is not cost-effective in any adolescent populations. Adult populations with high prevalence of HBV infection include injection-drug users, MSM, sexual contacts of persons with chronic HBV infection, and persons from countries with endemic HBV infection. When testing is performed, anti-HBc is the test of choice. Testing should not be a barrier to vaccination of susceptible persons, especially in populations that are difficult to access, and the first dose of vaccine should be administered at the same time that serologic testing is initiated.

As hepatitis B vaccination becomes more widespread, more persons will present with a history of vaccination and most will not have a personal vaccination record. However, serologic testing in persons with a history of previous hepatitis B vaccination may not be helpful because of the loss of detectable antibody. Without a vaccination record, obtaining a careful history (e.g., number of doses, schedule, and age at immunization) is the only way to determine if the person most likely received the complete hepatitis B vaccine series. Administration of additional doses of vaccine beyond the three-dose series is not harmful.

Postexposure Prophylaxis

Exposure to Persons Who Have Acute Hepatitis B

Sex Contacts. Previously unvaccinated sex partners of persons with acute hepatitis B should receive postexposure immunization with HBIG and hepatitis B vaccine within 14 days after the most recent sexual contact. HBIG has been shown to be required for effective postexposure protection in this setting. Administration of vaccine with HBIG in this setting confers long-term protection in the event the person with acute hepatitis B becomes chronically infected; simultaneous administration of HBIG and hepatitis B vaccine does not reduce vaccine effectiveness. Testing sex partners for susceptibility to HBV infection (anti-HBc) can be considered if it does not delay postexposure immunization beyond 14 days.

Nonsexual Household Contacts. Nonsexual household contacts of patients who have acute hepatitis B are not at increased risk for infection unless they have other risk factors or are exposed to the patient's blood (e.g., by sharing a toothbrush or razor blade). However, vaccination of household contacts is encouraged, especially for children and adolescents. If the patient with acute hepatitis B becomes chronically infected (i.e., remains HBsAg-positive after 6 months), all household contacts should be vaccinated.

Exposure to Persons Who Have Chronic HBV Infection

Most HBsAg-positive persons are identified during routine screening (e.g., blood donation and prenatal evaluation) or clinical evaluation. Active postexposure prophylaxis with hepatitis B vaccine alone is recommended for sex or needle-sharing partners and non-sexual household contacts of persons with chronic HBV infection. Because identifying the time of the last contact can be difficult, hepatitis B vaccination provides both preexposure and postexposure protection. Although the effectiveness of active postexposure immunization has not been evaluated for sex contacts of persons with chronic HBV infection, it provides high-level protection (90%) against perinatal HBV infection, where the intensity of exposure is greater than that among household or sex contacts of chronically infected persons.

Postvaccination testing (anti-HBs) should be considered for sex partners of persons with chronic HBV infection. Although most persons are expected to respond to vaccination, those found to be antibody-negative should receive a second, complete vaccination series. Those persons found to be antibody-negative after revaccination should be counseled about abstinence and the use of other methods to protect themselves from sexual HBV transmission.

Special Considerations

Pregnancy

All pregnant women receiving STD services should be tested for HBsAg, regardless of whether they have been previously tested. If positive, this test result should be reported to state perinatal immunization or HBV prevention programs to ensure proper case management of the mother and appropriate postexposure immunization of her at-risk infant. HBsAg-negative pregnant women seeking STD treatment who have not been previously vaccinated should receive hepatitis B vaccine, as pregnancy is not a contraindication to vaccination.

HIV Infection

HBV infection in HIV-infected persons is more likely to result in chronic HBV infection. HIV infection also can impair the response to hepatitis B vaccine. Therefore, HIV-infected persons who are vaccinated should be tested for anti-HBs 1--2 months after the third vaccine dose. Revaccination with three more doses should be considered for persons who do not respond initially to vaccination. Those who do not respond to additional doses should be advised that they might remain susceptible to HBV infection and should be counseled in the use of methods to prevent HBV infection.

Victims of Sexual Assault

Studies have not determined the frequency with which HBV infection occurs following sexual abuse or rape. Fully vaccinated victims of sexual assault are protected from HBV infection and do not need further doses. For a victim who is not fully vaccinated, the vaccine series should be completed as scheduled. Unvaccinated persons in this setting should be administered active postexposure prophylaxis (i.e., vaccine alone) upon the initial clinical evaluation. Unless the offender is known to have acute hepatitis B, HBIG is not required.

Because sexual abuse of children frequently occurs over a prolonged period of time, the last exposure is often difficult to determine. However, when sexual abuse is identified, hepatitis B vaccination should be initiated in previously unvaccinated children.

Hepatitis C

HCV infection is the most common chronic bloodborne infection in the United States; an estimated 2.7 million persons are chronically infected (101). More than two thirds of all infected persons are aged <50 years. Persons with acute HCV infection typically are either asymptomatic or have a mild clinical illness. The average time from exposure to seroconversion is 8--9 weeks, and antibodies to HCV (anti-HCV) can be detected in >97% of persons by 6 months after exposure. Chronic HCV infection develops in most persons (75%--85%) after acute infection; 60%--70% have evidence of active liver disease. Most infected persons may not be aware of their infection because they are not clinically ill. However, infected persons serve as a source of transmission to others and are at risk for chronic liver disease or other HCV-related chronic diseases for at least 2 decades after infection.

HCV is most efficiently transmitted by direct percutaneous exposure to infected blood (e.g., by receipt of blood transfusion from an infected donor or through use of injection drugs). Although less efficient, occupational, perinatal, and sexual exposures also can result in transmission of HCV. No association has been documented between HCV and military service or HCV and exposures resulting from medical, dental, or surgical procedures; tattooing; acupuncture; ear piercing; or foreign travel (102).

The greatest variation in prevalence of HCV infection occurs among persons with different risk factors for infection. The highest prevalence of infection is found among those with substantial or repeated direct percutaneous exposures to blood (e.g., IDUs, persons with hemophilia treated with clotting factor concentrates produced before 1987, and recipients of transfusions from HCV-positive donors). Moderate prevalence is found among persons with frequent but limited direct percutaneous exposures (e.g., long-term hemodialysis patients). Lower prevalence occurs among persons with inapparent percutaneous or mucosal exposures or sexual exposure and among those with limited, sporadic percutaneous exposures (e.g., health-care workers). Lowest prevalence of HCV infection is found among persons with no high-risk characteristics (e.g., blood donors).

Sexual Activity

Although the role of sexual activity in the transmission of HCV remains controversial, results from several types of studies indicate that sexual activity is associated with HCV transmission (103,104). These studies reported independent associations between HCV infection and a) exposure to an infected sex partner, b) increasing numbers of partners, c) failure to use a condom, d) history of STD, e) heterosexual sex with a male IDU, and f) sexual activities involving trauma.

In contrast, a low prevalence (average: 1.5%; range: 0%--4.4%) of HCV infection has been demonstrated in studies of long-term spouses of patients with chronic HCV infection who had no other risk factors for infection. One study has found an association between HCV infection and male homosexual activity, and at least in STD clinic settings, the prevalence rate of HCV infection among MSM generally has been similar to that of heterosexuals (105). Because sexual transmission of bloodborne viruses is more efficient among homosexual men compared with heterosexual men and women, it is unclear why HCV infection rates are not substantially higher among MSM compared with heterosexuals. This observation and the low prevalence of HCV infection observed among the long-term steady sex partners of persons with chronic HCV infection have raised doubts about the importance of sexual activity in the transmission of HCV. Unacknowledged percutaneous exposures (i.e., illegal injection-drug use) might contribute to increased risk for HCV infection among such persons.

Although inconsistencies exist between studies, data indicate overall that sexual transmission of HCV can occur and accounts for up to 20% of HCV infections (102). The substantial contribution of sexual transmission to the disease burden in the United States relative to the inefficiency with which the virus appears to be spread in this manner can be explained. Because sexual activity with multiple partners is a common behavior among chronically infected persons and because of the substantial number of these persons, multiple exposure opportunities exist. However, more data are needed to determine the risk for, and factors related to, transmission of HCV between sex partners, including whether other STDs promote the transmission of HCV by influencing viral load or modifying mucosal barriers.

Increased HCV viral load or coinfection with HIV (known to increase perinatal transmission of HCV) may increase the risk for sexual transmission. A recent study involving hemophilic men demonstrated that dually infected men had a higher HCV load than those infected with HCV alone, and that a higher HCV load was associated, though not significantly, with an increased risk for HCV transmission to female partners (106).

Diagnosis and Treatment

The diagnosis of HCV infection can be made by detecting either anti-HCV or HCV RNA. Anti-HCV is recommended for routine testing of asymptomatic persons and should include use of both EIA to test for anti-HCV and a supplemental antibody test (i.e., recombinant immunoblot assay [RIBA]) for all positive anti-HCV results. In settings where clinical services for liver disease are provided, use of reverse transcriptase polymerase chain reaction (RT-PCR) to detect HCV RNA might be appropriate to confirm the diagnosis of HCV infection (e.g., in patients with abnormal alanine aminotransferase [ALT] levels or with indeterminant supplemental anti-HCV test results), although RT-PCR assays are not currently FDA-approved.

Current approved therapy for HCV-related chronic liver disease includes alpha interferon alone or in combination with the oral agent ribavirin for a duration of 6--12 months. Because of advances in the field of antiviral therapy for chronic hepatitis C, standards of practice might change, and clinicians should consult with specialists knowledgeable about this virus. The National Institutes of Health Consensus Development Conference Panel recommended that therapy for hepatitis C be limited to those patients with persistently elevated ALT levels, detectable HCV RNA, and histologic evidence of progressive disease (as characterized by liver biopsy findings indicating either portal or bridging fibrosis or at least moderate degrees of inflammation and necrosis).

Prevention

No vaccine for hepatitis C is available, and prophylaxis with immune globulin is not effective in preventing HCV infection after exposure. Reducing the burden of HCV infection and disease in the United States requires implementation of both primary and secondary prevention activities. Primary prevention reduces or eliminates HCV transmission; secondary prevention activities reduce liver and other chronic diseases in HCV-infected persons by identifying them and providing appropriate medical management and antiviral therapy, if necessary (102). Persons seeking care in STD clinics or other primary-care settings should be screened for risk factors for HCV infection, and those with the following risk factors should be offered counseling and testing:

• illegal injection drug use, even once or twice many years ago;
• blood transfusion or solid organ transplant before July 1992;
• receipt of clotting factor concentrates produced before 1987; and
• long-term hemodialysis.

Regardless of test results, persons who use illegal drugs or have multiple sex partners should be provided with information regarding how to reduce their risk for acquiring bloodborne and sexually transmitted infections and how to avoid transmitting infectious agents to others (e.g., through vaccination against hepatitis B and, if appropriate, hepatitis A). Persons who inject drugs should be counseled to stop using and get into a treatment program. If they are found at any follow-up visit to be continuing the use of these drugs, they should be counseled on how to inject safely (i.e., use of sterile, single-use equipment, including needles, syringes, cookers, cottons, and water each and every time they inject). Persons with multiple sex partners should be counseled regarding how to reduce the transmission of STDs (e.g., through abstinence or by decreasing the number of sex partners).

Persons who test negative for HCV who had a previous exposure should be reassured that they have not been exposed. Persons who test positive for HCV infection should be provided information regarding how to protect their liver from further harm, how to prevent transmission to others, and the need for medical evaluation for chronic liver disease (CLD) and possible treatment. To protect their liver from further harm, HCV-positive persons should be advised to avoid alcohol, avoid taking any new medicines (including over-the-counter and herbals) without checking with their doctor, and become vaccinated against hepatitis A or hepatitis B if they are not immune. To reduce the risk for transmission to others, HCV-positive persons should be advised not to donate blood, body organs, other tissue, or semen and not to share any personal items that may have blood on them (e.g., toothbrushes and razors).

HCV-positive persons with one long-term, steady sex partner do not need to change their sexual practices. They should discuss the low but present risk for transmission with their partner and discuss the need for counseling and testing. HCV-positive women do not need to avoid pregnancy or breastfeeding.

Postexposure Follow-Up

No postexposure prophylaxis is effective against HCV. Testing to determine whether HCV infection has developed is recommended for health-care workers after percutaneous or permucosal exposures to HCV-positive blood and for children born to HCV-positive women.

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