BACKGROUND

Acute viral hepatitis is a term that is generally given to the disease condition attributed to a group of viruses that have the propensity to infect the liver and cause necroinflammation. Although these hepatotropic viruses share a common clinical presentation, they belong to different virus families, have different modes of transmission, and differ in their propensity to lead to chronic infection (Table 1.1). Even as acute viral hepatitis remains an important public health prob- lem in the United States, it is noteworthy that there has been and continues to be a decline in the number of new infections of hepatitis A, B, and C (Table 1.2).

It is important to keep in mind that there are a number of conditions that can have a clinical presentation consistent with an acute hepatitis – elevated serum aminotransferases with variable elevations in bilirubin levels. Aside from the hepatotropic viruses, other viruses such as the herpes viruses can also lead to acute hepatitis. The differential diagnoses for acute hepatitis include alcoholic hepatitis, acute Budd-Chiari syndrome, drug-induced liver injury, shock liver, autoimmune hepatitis, biliary obstruction, and Wilson's disease (Table 1.3). A careful history and physical examination can usually point the clinician to the appropriate diagnostic evaluation to arrive at a correct diagnosis. This chapter will review the hepatotropic viruses – hepatitis A to E.

ACUTE HEPATITIS A

In 1973, Feinstone and colleagues first identified the hepatitis A virus (HAV) in the stool samples of normal volunteers who were infected with HAV and had developed acute hepatitis.