Basic Facts About Hepatitis A, B, and C--  How you can contract it; Functions of the liver; What can happen when hepatitis progresses--fibrosis, cirrhosis, liver cancer, liver failure

Hepatitis is considered one of the most prevalent health problems of the 1990s. The World Health Organization reports that 1.4 million cases of hepatitis A are treated annually worldwide. In the United States, close to 5 million adults have hepatitis B or C, and this may be only a small percentage of the total of infected individuals.

Hepatitis A:

Hepatitis A (HAV), the most prevalent type of hepatitis worldwide, strikes more than 150,000 people in the United States annually.

Hepatitis B:

Each year, more than 250,000 people contract hepatitis B (HBV) in the United States.

Hepatitis C:

The Centers for Disease Control and Prevention (CDC) estimates that up to 30,000 individuals acquire hepatitis C (HCV) infections in the United States each year. In other parts of the world, the rates of infection and numbers in infected individuals range as high as 20 percent of the population. Called "an emerging public health threat" and the "silent epidemic," hepatitis C is a leading cause of cirrhosis and liver cancer, and is now the leading reason for liver transplantation in the United States.

Risk factors

Major risk factors for hepatitis A

The CDC lists household or sexual contact, day care attendance or employment, and recent international travel to areas with poor sanitation as major known risk factors for infection with hepatitis A. Eating food prepared by infected food handlers and using contaminated needles are other risk factors.

Major risk factors for hepatitis B

In the United States, the major risk factors for hepatitis B are unprotected sex with multiple partners and intravenous (IV) drug use.

Major risk factors for hepatitis C

The major risk factors for acquiring hepatitis C are IV drug use and transfusion of blood or blood products prior to 1992. Other risk factors also contribute.

A complete list of risk factors for acquiring hepatitis A, B, and C is provided in the following table.

Major risk factors for hepatitis A, B, and C
------------------------------------------------------------------------------
HEPATITIS A

• Person-to-person contact
• Poor personal hygiene
• Poor sanitation
• Unsafe sexual practices
• Employment of contact with day care centers and healthcare institutions such
  as nursing homes
• Street drug use

HEPATITIS B

• Hemodialysis
• Patients of custodial institutions for developmentally disabled
• Exposure to blood/blood clot products
• Needle-stick injury
• Sexual activity with multiple (heterosexual or homosexual) partners
• IV drug use
• Infants of HBV-positive mothers
• Tattooing
• Body piercing 

HEPATITIS C

• Hemophilia
• Hemodialysis
• Organ transplant
• IV drug use
• Blood transfusion prior to 1992
• Needle-stick injury
• Tattooing
• Body piercing
• Sexual activity with multiple partners

About 40 percent of people with hepatitis C have a history of IV drug use. Another 40 percent do not know the source of infection. The remaining 20 percent of hepatitis C cases may be attributed to household contact with a person known to have hepatitis, sexual contact with multiple partners, transfusion-associated disease, or occupational exposure. 

THE LIVER

Why so important?

Just as you cannot live without your heart or brain, you cannot live without your liver. Your liver performs many functions that are vital to survival. It transforms food into usable body chemicals. It filters waste, bacteria, and poisons from your blood. The liver stores vitamins and sugars that your body uses for energy.

The liver is a wedge-shaped organ located underneath the rib cage. Weighing close to 3 pounds, the liver is the body's largest internal organ. It has four main functions in the body: purification, synthesis, storage, and transformation.

The liver's many roles

Purification.

Your liver changes toxic substances, including alcohol, into harmless substances. Did you know that, even in healthy people, the liver processes alcohol as a poison? While inactivation of substances like alcohol and nicotine is good for the body as a whole, liver cells can be damaged in the process. Detoxification of alcohol, for example, can lead to cirrhosis. Your liver also changes certain medicines into a form your body can use, and inactivates other medicines after they've worked.

Synthesis.

Your liver takes simple chemical building blocks and combines them to manufacture (synthesize) more complex substances. For example, the liver manufactures most of the proteins found in the blood, as well as those needed to clot blood, make new cells, and cause chemical reactions inside of cells.

Storage.

The liver is a warehouse for your body. Besides storing minerals and vitamins, the liver stores sugars that your body uses for energy. Your liver releases these sugars into the bloodstream between meals when other parts of your body, like muscles or the brain, need more energy.

Transformation.

About 90 percent of the food you eat passes through your liver before it can be used. Your liver transforms food into vital body chemicals, including proteins, fats, and cholesterol. It also helps to digest fat and important vitamins carried in fats. When all of this is completed, your liver then sends this nourishment through the blood for cells to use. When your liver is not well The normal liver is smooth and firm to the touch. Progressive liver damage can lead to fibrosis, shrinking and hardening, and formation of nodules. In cirrhosis, the liver may become small and hard, with extensive scarring and many nodules.

As mentioned earlier, hepatitis is an inflammation of the liver. As liver disease progresses, other changes occur and damage to the liver increases. For example:

Fibrosis.

After becoming inflamed, the liver tries to repair itself by forming tiny scars. This scarring, called "fibrosis," makes it difficult for the liver to do its job. As damage continues, many scars form and begin to join together, leading to the next stage - cirrhosis. Certain HIV medications can be hard on the liver. It is possible that certain HIV medications may contribute to fibrosis which may lead to cirrhosis.

Cirrhosis.

With cirrhosis, large areas of the liver become permanently scarred from repeated damage. The liver begins to shrink and become hard. Chronic viral hepatitis is a common cause of cirrhosis, as is alcoholism. Scarring prevents blood from flowing freely through the liver, severely impairing liver function.

Liver failure.

As cirrhosis worsens, most liver function is lost. This means the liver is unable to filter wastes, toxins, and drugs from the blood. It can no longer produce the clotting factors necessary to stop bleeding. Fluid builds up in the abdomen and legs, bleeding in the intestines is common, and eventually mental functioning is slowed. At this point, a liver transplant is the only option.

Liver cancer.

Sometimes damage to liver cells includes altering the genes inside cells in a way that causes them to become cancerous. Patients with chronic hepatitis B or C are at higher risk for this form of cancer.