Hepatitis C

Scott Holmberg

INFECTIOUS AGENT

Hepatitis C is caused by the hepatitis C virus (HCV), a spherical, enveloped, positive-strand RNA virus, approximately 50 nm in diameter.

MODE OF TRANSMISSION

Transmission of HCV is bloodborne and occurs mainly through sharing drug-injection equipment, from transfusion of unscreened blood, or from untreated clotting factors. In developing countries, unsterile medicinal and other injection practices account for many infections. HCV is infrequently transmitted through sexual contact.

EPIDEMIOLOGY

Approximately 3% (170 million) of the world’s population has been infected with HCV. For most countries, the prevalence of HCV infection is <3%. The prevalence is higher (up to 15%) in some countries in Africa and Asia and highest (>15%) in Egypt (Map 3-05). The most frequent mode of transmission in the United States is through sharing drug-injecting equipment among people who inject drugs. Travelers’ risk for contracting HCV infection is generally low. For international travelers, the principal activities that can result in blood exposure are the following:

• Receiving blood transfusions that have not been screened for HCV
• Having medical or dental procedures
• Engaging in activities (such as acupuncture, tattooing, or injecting drug use) in which equipment has not been adequately sterilized or disinfected, or in which contaminated equipment is reused
• Working in health care fields (medical, dental, or laboratory) that entail direct exposure to human blood

Map 3-05. Prevalence of chronic hepatitis C infection

View Larger Map  PDF Version (printable) 

CLINICAL PRESENTATION

Most people (80%) with acute HCV infection have no symptoms. If symptoms occur, they may include loss of appetite, abdominal pain, fatigue, nausea, dark urine, and jaundice. Approximately 75%–85% of HCV-infected people develop chronic hepatitis C. The most common symptom of chronic infection is fatigue; severe liver disease develops in 10%–20% of infected people.

DIAGNOSIS

Two major types of tests are available: IgG assays for anti-HCV and nucleic acid amplification testing to detect HCV RNA in blood (viremia). Assays for IgM, to detect early or acute infection, are not available. Approximately 80% of people who seroconvert to anti-HCV, indicative of acute infection, will progress to chronic infection and persistently detectable viremia. False-negative antibody test results, while rare, may occur early in the course of acute infection, usually in the first 15 weeks after exposure and infection.

TREATMENT

Treatment for hepatitis C is rapidly evolving. In general, “sustained viral response” (considered a cure) is now achieved in 50% of patients taking pegylated interferon and ribavirin for 24–48 weeks. New oral agents added to a regimen of interferon and ribavirin are increasing cure rates to 85%–90% on initial treatment attempts; these may be approved and available by the time of printing this publication.

PREVENTIVE MEASURES FOR TRAVELERS

No vaccine is available, and immune globulin does not provide protection. When seeking medical or dental care, travelers should be alert to the use of medical, surgical, and dental equipment that has not been adequately sterilized or disinfected, reuse of contaminated equipment, and unsafe injecting practices (such as reuse of disposable needles and syringes). HCV and other bloodborne pathogens can be transmitted if tools are not sterile or the clinician does not follow other proper infection-control procedures (washing hands, using latex gloves, and cleaning and disinfecting surfaces and instruments). There are still a few areas of the world, such as parts of sub-Saharan Africa, where blood donors may not be screened for HCV. Travelers should be advised to consider the health risks if they are thinking about getting a tattoo or body piercing in areas where adequate sterilization or disinfection procedures might not be available or practiced.

BIBLIOGRAPHY

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