The silent dragon—hepatitis C - Home Study Program

AORN Journal, June, 2003 by Beverly Walker, Linda Howard

Hepatitis C has been called many names along its path to notoriety--the silent epidemic, the real Y2K bug, even the disease of the new millennium. Although it currently receives much attention, hepatitis C was not well studied or even identified until 1989. Referred to as non-A, non-B hepatitis or posttransfusion hepatitis, it was a poorly understood disease whose ramifications largely were unknown. Hepatitis C kills 8,000 to 10,000 people in the United Sates per year. (1)

In Chinese medicine, the liver is represented by a dragon and is said to store anger. (2) In a diseased state, however, the liver suffers quietly through the processes that ravage its cellular structure. It can take decades for an infected liver to develop the histological changes that lead to chronic hepatitis, liver cirrhosis, or hepatocellular carcinoma. A person infected with the virus that causes hepatitis C often has no symptoms until liver damage has occurred. (3)

The silence associated with hepatitis C could reflect not only the slow clinical course of the disease but also the millions of people who unknowingly are infected. Currently, it is estimated that approximately four million people in the United States have chronic hepatitis C, making it the most common bloodborne infection in this country. (4) Worldwide, 170 million people are thought to carry the virus that causes hepatitis C. Experts label the current known numbers of infected individuals as the tip of the iceberg. (5) The number of infected people in the United States probably is underestimated because chronic hepatitis has not been a disease reportable to the Centers for Disease Control and Prevention (CDC). The prison population in the United States, for example, is infected heavily with hepatitis C and is not included in these estimates. (6)

This article explores the natural progression of the virus, its effects on the liver, and populations at risk. Existing and emerging therapies are described, and a case study is presented involving one perioperative nurse's battle with the disease.

HEPATITIS VIRUSES

The virus that causes hepatitis C is one of seven identified hepatitis viruses that attack and damage liver cells. They are named alphabetically for the order of their discovery--A, B, C, D, E, F, and G. Although many different viruses can affect the liver and cause inflammation, including the viruses that cause yellow fever, herpes simplex, Epstein-Barr, and cytomegalovirus, hepatitis viruses are responsible for the majority of viral hepatitis cases. (7) Many of these viruses share the same symptoms, but they differ from one another in structure, characteristics, and severity. Hepatitis A virus (HAV) causes a short-term acute disease as a result of a foodborne and waterborne contamination. No treatment is available, but the body develops immune defenses against hepatitis A. Both hepatitis B and hepatitis C are bloodborne viruses, although the hepatitis B virus (HBV) is transmitted more easily than the hepatitis C virus (HCV), in part because the virus is secreted more readily in body fluids. Usually, HBV causes an acute disease, and the immune system mounts a successful defense in about 70% of cases. Just 20% to 30% of infected people develop chronic hepatitis. On the other hand, HCV rarely causes an acute infection, and it lingers for 10 to 20 years before causing permanent liver damage. (8) A vaccine is available for both HAV and HBV.

The HCV is a small, single-strand RNA virus that penetrates a liver cell and replicates outside of the cell's nucleus. It belongs to the flavivirus family and is one of the most heterogenous viruses found in nature. No two viral genomes are alike in a host, and for this reason, HCV often is able to escape the host's immune surveillance system. (9) It is this property that causes persistent infection to develop in 85% of people infected with HCV. This genetic diversity also creates a challenge in treating those infected with the disease and developing a vaccine to protect the uninfected. The approved first-line medications for treatment are interferon and ribavirin, but most patients relapse when treatment is stopped. (10)

Although HBV has been screened from the nation's blood supply since 1975, screening for HCV did not begin until just 13 years ago. People receiving blood transfusions before 1990 were unknowingly at risk for contracting HCV. It now is believed that more than 90% of posttransfusion hepatitis cases are attributable to HCV compared to just 2% for HBV. (11)

NORMAL LIVER ANATOMY AND PHYSIOLOGY

The liver is the largest internal organ in the human body (Figure 1). It weighs an average of 1,500 g and receives 30% of the body's cardiac output. It is encapsulated by a tough fibrous sheath called Glisson's capsule. The two major and two minor lobes of the liver are separated anteriorly by the falciform ligament that divides the larger right lobe from the left. Inferiorly, the caudate lobe is near the inferior vena cava and the quadrate lobe rests near the gallbladder. This vascular organ receives its blood supply from the portal vein and hepatic artery. The hepatic artery, portal vein, lymphatics, and nerves enter the liver through the hilus. This also is where the hepatic duct and hepatic vein jointly exit the liver. (12)