Hepatitis is the inflammation and damage of hepatocytes in the liver caused by hepatitis A, B, C, D, E viruses, alcohol, and medications. Viral hepatitis occurs at any age and is the most common cause of liver disease. The prevalence and incidence may be underreported because patients are often asymptomatic. Acute hepatitis is associated with all five types of viral hepatitis and rarely exceeds 6 months in duration. Chronic viral hepatitis is associated with hepatitis B, C, and D and may lead to the development of ascites, jaundice, hepatic encephalopathy, esophageal varices, cirrhosis, and hepatocellular carcinoma. This chapter focuses on the most common viral forms of hepatitis (hepatitis A, B, and C).
Hepatitis A virus (HAV) is an acute viral infection spread via the fecal-oral route. In the United States, HAV has declined considerably since the development of the hepatitis A vaccine, but HAV remains prevalent in underdeveloped countries. HAV is an RNA virus that impacts areas with inadequate sanitation and persons with poor hygienic practices. Other risk factors include IV drug use, exposure to infected individuals, and homosexual activity in men.
Hepatitis B virus (HBV) causes an acute and chronic viral infection. In the United States, acute HBV is transmitted through exposure to blood and bodily secretions, sexual activity, IV drug use, and occupational exposure. Despite having an effective vaccine against HBV, more than 300,000 newly diagnosed infections emerge annually. Approximately 10% to 15% of patients develop chronic HBV disease; therefore, 85% to 90% of acute HBV infections resolve without complications.
Hepatitis C virus (HCV) infection is the most common blood-borne infection in the United States. There are six geographically specific genotypes of HCV; however, only genotypes 1 to 4 are commonly encountered in the United States. For example, genotype 1 represents 75% of infections within the United States, whereas genotype 4 is common in the Middle East. HCV genotype is used to determine the duration of therapy and the likelihood of therapeutic response. The most common modes of transmission of HCV are IV drug use and blood transfusion prior to 1992 before blood banks began screening for HCV. Other HCV risk factors include tattoos, body piercings, and shared drug paraphernalia. HCV is rarely transmitted through sexual intercourse in heterosexual monogamous relationships. Approximately 10% to 15% of patients with acute HCV resolve without any further sequelae; therefore, 85% to 90% of HCV cases develop into chronic disease.
Clinical Presentation and Diagnosis
Signs and symptoms vary among patients and range from asymptomatic to liver failure. Asymptomatic patients may only present with mildly elevated liver enzymes. Common acute symptoms include fatigue, jaundice, nausea and vomiting, weight loss, fever, right upper quadrant pain, and splenomegaly. An overview of HAV, HBC, and HCV can be found in Table 40-1.