Chronic hepatitis is an inflammatory condition of the liver that persists for longer than six months. Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections account for roughly 75 percent of chronic hepatitis worldwide. Alcohol, drugs, chemicals, fatty liver and autoimmune disease also cause chronic hepatitis. The course of chronic hepatitis and the prognosis are variable, depending on the underlying cause and other factors relative to the individual.
Hepatitis B
Hepatitis B is a contagious blood-borne virus. In the United States, HBV is commonly contracted through sexual contact with an infected person or through sharing drug injection equipment or personal hygiene items such as razors or toothbrushes with an infected person. The U.S. Centers for Disease Control and Prevention (CDC) report that an estimated 800,000 to 1.4 million Americans have chronic hepatitis B. Between 15 and 40 percent of people with chronic hepatitis B will develop serious HBV-related health problems in their lifetimes, which may include cirrhosis, liver failure or liver cancer.
Hepatitis C
Hepatitis C is the most common cause of chronic liver disease in the United States. The CDC estimates approximately 3.2 million Americans have chronic HCV infection. HCV is a contagious blood-borne virus discovered in 1988. Prior to 1992, HCV was common in the national blood supply. This led to many infections through blood transfusions and contaminated blood-derived medicines. Chronic hepatitis C can lead to cirrhosis, liver failure or liver cancer.
Autoimmune Disease
Autoimmune hepatitis is caused by an errant attack on the liver by the body's immune system. This disease most commonly occurs in teens or young adults, though it can occur at any age. Females make up roughly 70 percent of people with autoimmune hepatitis. This form of chronic hepatitis can be rapidly progressive if not effectively treated. Cirrhosis or liver failure may occur.
Alcohol
Persistent, heavy alcohol consumption can cause chronic hepatitis. Alcohol is broken down by the liver, and some of the byproducts are toxic to liver cells. The presence of these toxins and the resultant liver injury trigger an inflammatory reaction that may lead to scarring, cirrhosis and liver failure.
Drugs and Chemicals
The liver is the primary processor of most drugs and chemicals that enter the body. Thus, the liver is vulnerable when it is subject to prolonged exposure to potentially damaging chemicals or drugs. A partial list of drugs that may cause chronic hepatitis includes methyldopa, amiodarone, isoniazid, anabolic steroids, oral contraceptives, methotrexate and statins. An extensive list of occupational chemicals can cause liver injury, including carbon tetrachloride, turpentine, urethane, toluene, phenol, chlorofluorocarbons, chromates, and arsenic and beryllium-containing compounds. Eliminating exposure to the injurious substance often halts disease progression and may allow for partial recovery.
Fatty Liver
As obesity rates in the United States soar, the prevalence of fatty liver has also increased dramatically. The National Institute of Diabetes and Digestive and Kidney Diseases reports that 10 to 20 percent of Americans have fatty liver; an additional two to five percent have a condition called nonalcoholic steatohepatitis or NASH. NASH is a form of chronic hepatitis characterized by fat in the liver cells and accompanying injury and inflammation. As the name implies, NASH is not caused by alcohol consumption. Although the underlying cause of NASH remains unclear at this time, the condition most frequently occurs in people who are overweight or obese. NASH can lead to cirrhosis and liver failure.
References
- American Gastroenterological Association: Understanding hepatitis
- Merck Manual: Chronic hepatitis
- National Institute of Diabetes and Digestive and Kidney Diseases: Chronic hepatitis C
- National Institute of Diabetes and Digestive and Kidney Diseases: Viral hepatitis A through E and beyond
- Centers for Disease Control and Prevention: Hepatitis B FAQs for health professionals
