Since then, the risk of contracting the hepatitis C virus from transfusions has dropped to almost zero. Most new cases are a result of needle sharing by drug users, according to the CDC. Other people may have been exposed through tattooing, dialysis or other activities in which blood is transferred.

Symptoms of liver damage don't usually emerge for 20 or 30 years. Many people have the virus and don't know it.

Get tested
In 1999, under federal mandate, hospitals and blood banks began to notify people who received blood from infected donors. But, according to the U.S. Food and Drug Administration, the virus was not identified until 1988, so only the blood of donors who have tested positive since that year will be traced back. Many people exposed through transfusions, and those and risk for other reasons, will not be notified. Nor will authorities be able to locate every blood recipient they want to contact.

So if you think you are at risk, what should you do?

"Don't panic," says Dr. Raymond Koff, a liver specialist at the MetroWest Medical Center in Framingham, Mass. Even if you were exposed to the virus, you may never become ill: Between 15 and 45 percent of those who contract hepatitis C "throw it off" on their own, without medical intervention. Many others carry the virus for years, with no ill effects.

But if there is any chance you could have been exposed, you should have a blood test even if you feel healthy, Koff says. You can test yourself at home with a kit from your drug store or ask your doctor to test you. Then, you can either rest assured that you don't have the virus, or seek medical help to manage the disease and avoid transmitting it to others.

Protect yourself - and others
"Hepatitis C is slowly progressive," Koff says. "It's unusual for anyone to get sick or have any complications during the first 20 years after they are exposed."

The liver is a key organ in the body. It manufactures protein, cleans the blood, and affects your metabolic processes. If the virus leads to scarring of the liver, or "cirrhosis," a liver transplant eventually may be needed. A small percentage of hepatitis C patients develop liver cancer.

If you have hepatitis C, it is important to determine whether you have liver damage, and whether treatment could be helpful.

Even if your case is mild, you should do everything you can to protect your liver.

• Avoid drinking alcohol "in all forms and in all amounts," Koff says.
• Consult with your physician before taking any drugs, including over-the counter and herbal medications. If you have liver damage, get vaccinated against other forms of hepatitis.
• Take care to prevent the virus from spreading.

The hepatitis C virus is blood borne; according to the CDC it is not transmitted through food or water or by casual contact. It is not spread by sneezing, hugging, coughing or breastfeeding, or by sharing eating utensils or drinking glasses. There is no reason for people with hepatitis C to avoid work or school, or for infected women to avoid pregnancy. The risk of transmission during childbirth is extremely low, according to Koff.

However, if you are infected, you should not share toothbrushes, razorblades, or personal items where blood may be transferred. "If you cut yourself, clean up the blood yourself or make sure that whoever cleans it up wears rubber or latex gloves," Koff says.

There is a small risk of transmission through blood during sex, so long-term monogamous partners should discuss whether they wish to use condoms. The CDC recommends that people with multiple sexual partners use latex condoms to prevent transmitting hepatitis C and a variety of sexually transmitted diseases.

Anyone who injects or uses street drugs should quit and join a drug treatment program, the CDC advises. If you use drugs and are unable to stop, don't reuse or share syringes, water or drug works, and get vaccinated against other forms of hepatitis.

Stay hopeful
Above all, Koff advises, "Take good care of yourself. " Make sure you maintain appropriate nutrition and a balanced diet; exercise if you feel like it. Koff also recommends joining a hepatitis C support group near where you live. You can find one through the American Liver Foundation or your local hospital.

"It is important to be hopeful," Koff says, and there is reason to be. Since 1992, the number of new infections in the United States has dropped from 200,000 a year to 40,000 a year, thanks to improved screening of donated blood.

While current treatments can have unpleasant side effects and are effective in fewer than 40 percent of cases, a new, sustained-release drug known as pegylated interferon is expected to be on the market within a year.

Whereas hepatitis C was once considered incurable, a small number of treated patients have remained free of the virus for 10 years. Now, for the first time, Koff says, doctors "are beginning to speak of a cure."