Acute hepatitis C virus infection: A chronic problem

Since the discovery of the hepatitis C virus (HCV) in the late 1980s, there has been an explosion of information regarding its natural history, treatment, and replication cycle. Nonetheless, there are still relatively few data regarding acute HCV infection. By convention, the term acute hepatitis refers to the presence of clinical signs or symptoms of hepatitis for a period of 6 months or fewer after the presumed time of HCV exposure. Early studies of posttransfusion patients who developed non-A, non-B hepatitis provide a clinical picture of early infection.1 Following the availability of specific serologic and virologic tests, most such patients were shown to have acute HCV infection. After acute infection, HCV RNA may become detectable in the serum/plasma in as little as 2 weeks (Fig. 1). Several weeks later, a high percentage of patients experience an increase in serum aminotransferase levels consistent with the development of acute hepatocellular injury. In the majority of cases, patients develop mild constitutional symptoms, including abdominal pain, nausea, vomiting, anorexia, and fatigue. During this acute infection, serum aminotransferases often peak below 1000 IU/mL and may return to normal levels. A minority develops sufficient elevations in bilirubin to lead to overt jaundice or the development of dark urine. Unless the clinical suspicion is high, few patients will be tested for HCV RNA or HCV antibody seroconversion. However, in the majority— but not all— of infected patients, HCV RNA persists, and a chronic disease state develops. Fig. 1 Natural history of HCV infection (upper panel) and immunologic responses to HCV infection (lower panel): (−) HCV RNA, (- - -) cellular response, and (· · ·) ALT. ALT indicates alanine aminotransferase; HCV, hepatitis C ... The reasons for the general lack of data regarding acute HCV infection are multifactorial and include (1) the relatively high percentage of asymptomatic or unrecognized early infections, (2) the lack of large-scale identification of chronic carriers in the general population who serve as a reservoir for infection, and (3) the decreased number of acute infections that occur in controlled clinical settings such as that of blood transfusions. These factors and the lack of nonprimate animal models necessitate reliance on retrospective studies in chronic carriers, the use of limited historical collections of banked sera, and the extrapolation of outcomes based on small disease outbreaks in unique settings (for example, transmission from a physician to a patient in the operating room setting or following parenteral exposure in healthcare workers). Moreover, there exist only a limited number of population cohorts that continue to experience high rates of HCV transmission (for example, Egypt); nonetheless, there is a growing body of information regarding the clinical presentation, natural history, and treatment outcomes of acute HCV infection. In this article, we review the current information regarding our understanding of the epidemiology, virology, and immunology of HCV with a particular emphasis on acute HCV infection. In addition, we review recent data related to interferon-based treatment intervention and propose an algorithm for the diagnosis and management of acute HCV infection.