Hepatitis C

Infectious Agent

Hepatitis C virus (HCV) is a spherical, enveloped, positive-strand RNA virus. Seven distinct HCV genotypes and 67 subtypes have been identified, the distribution of which vary geographically worldwide.

Transmission

Transmission of HCV is bloodborne and most often involves exposure to contaminated needles or syringes or receipt of blood or blood products that have not been screened for HCV. Although infrequent, HCV can be transmitted through other procedures that involve blood exposure, such as tattooing, during sexual contact, or perinatally from mother to child.

Epidemiology

Globally, an estimated 71 million people are living with HCV infection (chronically infected), and approximately 400,000 were estimated to have died from HCV-related liver disease in 2013. Although the quality of epidemiologic data and prevalence estimates vary widely across countries and within regions, the most recent global estimates indicate that the viremic prevalence of HCV infection (prevalence of HCV RNA) is <1.0% in most developed countries, including the United States (Map 4-5). The prevalence is considerably higher in some countries in Eastern Europe (3.3% in Russia, 2.2% in Latvia) and certain countries in Africa (6.3% in Egypt, 7.0% in Gabon), the Middle East (3.0% in Syria), the South Caucasus and Central Asia (4.2% in Georgia, 4.3% in Uzbekistan) and southern and eastern Asia (3.8% in Pakistan, 6.4% in Mongolia, 2.1% in Taiwan). The most frequent current mode of transmission in the United States and most developed countries is through sharing of drug preparation and drug-injection equipment. In countries where HCV infection prevalence is higher relative to developed countries, the predominant mode of transmission is from unsafe injections and other health care exposures where infection-control practices are poor. Travelers’ risk for contracting HCV infection is generally low, but they should exercise caution, as the following activities can result in blood exposure:

  • Receiving blood transfusions that have not been screened for HCV
  • Having medical or dental procedures
  • Activities such as acupuncture, tattooing, being shaved, or injection 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 4-5.Prevalence of hepatitis C virus infection
Map 4-5.Prevalence of hepatitis C virus infection

The Polaris Observatory HCV Collaborators. Global prevalence and genotype distribution of hepatitis C virus infection in 2015: a modelling study. Lancet Gastroenterol Hepatol. 2017;2:161–76.

Clinical Presentation

HCV is a major cause of cirrhosis and hepatocellular cancer and is the leading reason for liver transplantation in the United States. Most people (80%) with acute HCV infection have no symptoms. If symptoms occur, they are indistinguishable from other forms of acute viral hepatitis and may include loss of appetite, abdominal pain, fatigue, nausea, dark urine, and jaundice. Of those infected, approximately 75%–85% will remain infected unless treated with antiviral medications. For people who develop chronic HCV infection, the most common symptom is fatigue. Cirrhosis develops in approximately 10%–20% of people after 20–30 years of chronic infection. This progression is often clinically silent, and evidence of liver disease may not occur until late in the course of the disease. HCV testing is required for diagnosis. However, testing is not routinely provided in many countries, and most HCV-infected people are unaware of their infection.

Diagnosis

Two major types of tests are available: IgG assays for HCV antibodies 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 70%–75% of people who seroconvert to anti-HCV, indicative of acute infection, will progress to chronic infection and persistent viremia. Because a positive HCV antibody test cannot discriminate between someone who was previously infected but resolved or cleared the infection and someone with current infection, it is essential that HCV RNA testing follow a positive HCV antibody test to identify people with current (chronic) HCV infection. Hepatitis C is a nationally notifiable disease.

Treatment

Since 2014, several new all-oral direct-acting antiviral agents have been approved for use in the United States and other countries. These new treatment regimens are of short duration (typically 12 weeks) with few side effects and cure rates exceeding 90% for those who complete treatment, regardless of HCV genotype, prior treatment status, and the presence of cirrhosis. Travelers who think they may have been exposed should be tested for HCV upon return and, if found to have current infection (HCV RNA-positive), be referred for care and evaluated for treatment. The most up-to-date treatment guidelines and information can be found at www.hcvguidelines.org.

Prevention

No vaccine is available to prevent HCV infection, nor does immune globulin provide protection. Before traveling, people should check with their health care providers to understand the potential risk of infection and any precautions they should take. When seeking medical or dental care, travelers should be alert to the use of medical, surgical, or dental equipment that has not been adequately sterilized or disinfected; reuse of contaminated equipment; and unsafe injection practices (such as reuse of disposable needles and syringes). HCV and other bloodborne pathogens can be transmitted if instruments 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). In some parts of the world, such as parts of sub-Saharan Africa, blood donors may not be screened for HCV. Travelers should be advised to consider the health risks if they are considering a tattoo or body piercing or having a medical procedure in areas where adequate sterilization or disinfection procedures might not be practiced. Travelers should be advised to seek testing for HCV upon return if they received blood transfusions or sustained other blood exposures for which they could not assess the risks.

CDC website: www.cdc.gov/hepatitis/HCV

Bibliography

  1. American Association for Study of Liver Diseases (AASLD), Infectious Diseases Society of America (IDSA). Recommendations for testing, managing, and treating hepatitis C. [updated 2017 Sep 21]. Available from: www.hcvguidelines.org/.
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  4. Global Hepatitis Report 2017. Geneva: World Health Organization; 2017. Licence: CC BY-NC-SA 3.0 IGO. Available from: http://apps.who.int/iris/bitstream/10665/255016/1/9789241565455-eng.pdf....
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Author

Philip Spradling