What Is Hepatitis?
Many people mistakenly believe that hepatitis is synonymous with viral hepatitis, and that all forms of hepatitis are contagious. Actually, the word hepatitis is a catch-all term that refers to any inflammation of the liver; it does not imply a specific cause or contagiousness (inflammation of the liver is defined as an irritation or swelling of liver cells).
Hepatitis can be acute (inflammation of the liver that lasts less than six months) or chronic (inflammation of the liver that lasts greater than six months) and has a number of different causes. It can be caused by a group of viruses known as the hepatitis viruses, including A, B, C, D, and E. Other viruses may also be the culprit, such as those that cause mononucleosis (the Epstein-Barr virus) or chickenpox (the varicella virus).
Hepatitis also applies to inflammation of the liver caused by drugs and alcohol abuse or toxins in the environment. In addition, people also can develop hepatitis from other factors, such as fat accumulation in the liver (called fatty liver hepatitis or NASH – nonalcoholic steatohepatitis), trauma, or an autoimmune process in which a person's body makes antibodies that attack the liver (autoimmune hepatitis).
Viral hepatitis is common. Thousands of cases are reported to the CDC each year, but researchers estimate that the true number of people in the U.S. who have either acute or chronic hepatitis is much higher than what is reported. This is because most cases of hepatitis are silent or go undiagnosed because they are mistaken for the flu. Hepatitis can be serious, because it interferes with the liver's many functions. Among other things, the liver produces bile to aid digestion, regulates the chemical composition of the blood, and screens potentially harmful substances from the bloodstream.
The five hepatitis viruses can be transmitted in different ways, but they all have one thing in common: They infect the liver and cause it to become inflamed. Generally, the acute phase of the disease lasts from two to three weeks; complete recovery takes about six months. Many patients recover with a lifelong immunity to the disease, but some hepatitis victims die in the acute phase. Hepatitis B and C may progress to chronic hepatitis, in which the liver remains inflamed for more than six months. This condition can lead to cirrhosis, liver cancer, and possibly death.
What Causes Hepatitis?
Although their effects on the liver and the symptoms they produce can be similar, the various forms of hepatitis are contracted in different ways. In the case of viral hepatitis, the severity and duration of the disease are largely determined by the organism that caused it.
Hepatitis A (HAV), which is generally contracted orally through fecal contamination of food or water, is considered the least dangerous form of the disease, because it almost always resolves on its own. Also, it does not lead to chronic inflammation of the liver. However, approximately 15% of people with hepatitis A become so ill that they require hospitalization, and, each year, approximately 100 people either die or require a liver transplant as a result of liver failure due to HAV. That is why anyone at increased risk for becoming infected, as well as all people with any form of chronic liver disease, should obtain the hepatitis A vaccine. The hepatitis A virus commonly spreads through improper handling of food, contact with household members, sharing toys at daycare centers, and eating raw shellfish taken from polluted waters. The following groups of people are at increased risk for contracting HAV:
- People who travel to developing countries, including tourists, military personnel, Peace Corps workers, and missionaries
- Men who have sex with men
- People who practice oral-anal sex
- Intravenous drug users (both present and former users)
- People who have contact with sewage (this appears to be an insignificant mode of transmission in the U.S.)
- Employees and children (particularly those in diapers) at daycare centers
- Employees and patients in institutions for the mentally disabled (incidence has greatly decreased since sanitary conditions have improved)
- People who work with primates, such as apes and monkeys, which can also transmit HAV
- People who live in crowded conditions with poor sanitation
