An estimated 3 percent of the world's population — more than 170 million people — carry a mysterious virus that silently attacks their liver, often without their knowledge. That's because up to 90 percent of those infected with the hepatitis C virus have no symptoms at all. In fact, most people don't know they have the disease until decades later when liver damage shows up during routine medical tests. Sometimes people may learn they have hepatitis C when they try to donate blood because blood banks now routinely screen for the virus.

The liver — which weighs between 3 and 4 pounds — is the largest and most complex internal organ in your body. It sits behind your lower ribs on the right side of your abdomen and performs a variety of crucial functions — including detoxifying harmful substances, purifying your blood and manufacturing vital nutrients.

Hepatitis C is one of five currently identified hepatitis viruses. The others are A, B, D and E. All cause the liver to become inflamed, which interferes with its ability to function. Hepatitis C is generally considered to be among the most serious of these viruses.

In many cases hepatitis C leads to chronic liver diseases such as cirrhosis (irreversible and potentially fatal scarring of the liver), liver cancer or liver failure. It ranks second only to alcoholism as a cause of liver disease and is the leading reason for liver transplants in the United States.

Although vaccines are used for hepatitis A and B, there is currently no vaccine for hepatitis C. There is a standard treatment for the virus. But the treatment is not universally effective, so the search for new treatments is ongoing.

Signs and Symptoms

Normally, hepatitis C produces no symptoms in its earliest stages. If you do have symptoms, they'll generally be mild and flulike. They include:

• Slight fatigue
• Nausea or poor appetite
• Muscle and joint pains
• Tenderness in the area of the liver

Even if you develop chronic hepatitis from the hepatitis C virus, you may have few, if any, symptoms. In many cases symptoms might not appear for up to 30 years, though you may experience one or more of the following:

• Fatigue
• Lack of appetite
• Nausea and vomiting
• Persistent or recurring yellowing of your skin and eyes (jaundice)
• Low-grade fever

Hepatitis C can cause damage to your liver even if you don't have symptoms. You're also able to pass the virus to others without having any symptoms yourself. That's why it's important to be tested if you think you've been exposed to hepatitis C or if you engage in behavior that puts you at risk.

Causes

In general, you contract hepatitis C by coming in contact with blood contaminated with the virus. Most people with hepatitis C became infected through blood transfusions received before 1992, the year improved blood-screening tests became available. You can also contract the virus by injecting drugs with contaminated needles or inhaling cocaine through contaminated straws. Less commonly, you can contract the virus from needles used in tattooing or body piercing. In rare cases hepatitis C may also be transmitted sexually.

Risk Factors

Effective blood-screening procedures have greatly reduced the chances of hepatitis C infection from transfusions. But if you received a blood transfusion before 1992, you're at risk of hepatitis C.

You are also at risk if you:

• Used illegal intravenous or intranasal drugs, such as cocaine, even once
• Received an organ transplant before 1992
• Are a health care worker who was exposed to the infected blood of others
• Received clotting factor concentrates before 1987 or have the clotting disease hemophilia and received blood before 1992

Complications

Fifteen percent to 20 percent of people infected with hepatitis C are able to fight off the virus on their own without suffering liver damage. For the rest, the disease settles in and slowly attacks the liver.

About 85 percent of people infected with hepatitis C develop chronic hepatitis. Twenty percent develop cirrhosis, usually within the first 2 decades after infection. Of those who develop cirrhosis, fully half progress to end-stage liver disease or liver cancer.

Health experts predict that hepatitis C-related deaths may soon overtake the number of AIDS-related deaths in the United States. Currently, about 10,000 people die each year from hepatitis C, but that number is expected to triple in 20 years. Even so, your chances of survival are high. Right now, more than 99 percent of people with hepatitis C survive.

Treatment

A diagnosis of hepatitis C doesn't necessarily mean you'll need treatment. The National Institutes of Health (NIH) recommends treatment for hepatitis C if you have one or more of the following:

• A positive hepatitis C ribonucleic acid (RNA) test, which indicates circulating virus in your bloodstream
• A biopsy that indicates significant liver damage
• Elevated levels in your blood of a liver enzyme called alanine aminotransferase (ALT)

Even with the NIH recommendation, doctors continue to debate who should be treated. If you have only slight liver abnormalities, your doctor may decide against medical treatment because your long-term risk of developing a serious disease is slight and the side effects of treatment can be severe.

On the other hand, because there is no foolproof way to know whether you'll develop liver disease later on, your doctor may choose to fight the virus. Improved treatment methods and a higher success rate in fighting hepatitis sometimes tip the argument in favor of more aggressive approaches.

  Medications

Until recently the best weapon against hepatitis C was interferon, a drug that inhibits viral replication. But interferon worked in only about 20 percent of cases. Now injections of interferon are usually combined with oral doses of ribavirin, a broad-spectrum antiviral agent. Treatment usually takes from 6 months to 1 year and is successful in about 40 percent of people with hepatitis C.

Recent studies have shown that another drug, pegylated (PEG) interferon, may be twice as effective as regular interferon. Clinical trials are now under way to determine if PEG interferon will prove even more effective in combination with ribavirin. The drug is expected to be approved for use by the end of 2001.

Side effects from drug therapy include severe flulike symptoms from the interferon and a temporary drop in white cell or platelet counts in your blood (anemia). Chronic side effects, which affect about half of those receiving treatment with interferon-ribavirin, include extreme fatigue, anxiety, irritability and depression. A small percentage of people may experience psychosis or suicidal behavior.

If you have a history of major depression, treatment with interferon isn't recommended. You're also not a good candidate for this treatment if you have untreated thyroid disease, low blood cell counts, or autoimmune disease or if you drink alcohol or use drugs.

If treatment isn't effective for you or you're unable to tolerate the side effects, you may have few other options. But researchers are investigating the use of protease inhibitors in people with hepatitis C. These are the same medications that have helped some people with HIV or AIDS. In the future it may also be possible to treat hepatitis C with gene therapy.

  Liver Transplantation

The best hope for people with end-stage liver disease is liver transplantation. Unfortunately, the number of people awaiting transplants far exceeds the number of donated organs. But several new developments in transplantation may make it possible for more people to receive the organs they desperately need.

These developments include the donating of liver segments from living relatives, splitting one donated liver between two recipients and, especially, new approaches to liver transplants for people with hepatitis C.

Until recently hepatitis C-infected livers were routinely discarded. But studies show that people already infected with hepatitis C who receive livers from hepatitis C-positive donors do as well as if they'd received a liver not infected with the virus. This may mean that many more livers will become available for people with hepatitis C.

Prevention

Because there's no effective vaccine for hepatitis C, the only way to protect yourself is to avoid becoming infected. That means taking the following precautions:

• Avoid unprotected sex with multiple partners or with one partner whose health status is uncertain.
• Don't share needles or other drug paraphernalia. Contaminated drug paraphernalia is responsible for about half of all new hepatitis C cases.
• Avoid nasal use of cocaine.
• Avoid body piercing and tattooing unless you're absolutely certain the equipment is sterile.

Self-Care

If you're diagnosed with hepatitis C, your doctor will likely recommend certain lifestyle changes. These simple measures will help keep you healthy longer and protect the health of others as well:

• Eliminate alcohol consumption. Alcohol speeds the progression of liver disease.
• Avoid medications that may cause liver damage. Your doctor can advise you about these medications, which may include over-the-counter (OTC) medications as well as prescription drugs.
• Maintain a healthy life style. Be sure you eat a healthy diet that emphasizes fresh fruits, vegetables and whole grains. Exercise regularly and get plenty of rest.
• Help prevent others from coming in contact with your blood. Cover any wounds you have and don't share razors or toothbrushes. Don't donate blood, body organs or semen. Advise health care workers that you have the virus.

Complementary and Alternative Medicine

In Europe, the herb milk thistle (Silybum marianum) has been used for centuries to treat jaundice and other liver disorders. Today, scientific studies have confirmed that the chief constituent of milk thistle, silymarin, may aid in healing and rebuilding the liver. Silymarin seems to stimulate the production of antioxidant enzymes that help the liver neutralize toxins. It also seems to increase the production of new liver cells and may even improve the severe scarring of cirrhosis. These benefits have not been proven in people with hepatitis C, however. Furthermore, although milk thistle may help the liver, it will not cure hepatitis C or prevent the disease from recurring.

Milk thistle is available in capsule or alcohol-free extracts. Check with your doctor before trying this or any other herb to make sure it won't interact negatively with other medications you've been prescribed or are taking over-the-counter.