Hepatitis is an infection that attacks the liver, the organ that performs the critical functions of storing energy, filtering poisons, and metabolizing alcohol and drugs.
Several viruses cause hepatitis. The principal ones are hepatitis A, B, and C. Hepatitis A is a short-term threat, while the others pose more menacing, long-term complications that can take years or even decades to emerge. The viruses differ in symptoms, transmission, and prevention safeguards.
It's not surprising that even doctors sometimes can't keep it all straight. Public awareness is just beginning, says Dr. Harold Margolis, chief of the Hepatitis Branch at the Centers for Disease Control and Prevention (CDC). "Ten years ago, most people associated hepatitis with bad food."
While understanding the hepatitis alphabet isn't as easy as A-B-C, the following rundown should give you enough information to earn a passing grade.
Hepatitis A is caused by a virus that survives in human feces and is passed through contaminated food and water. It strikes as many as 150,000 Americans a year.
People with hepatitis A typically experience fever, nausea, vomiting, fatigue, diarrhea, appetite loss, and sometimes jaundice (yellowing of the skin and eyes), says Dr. Eugene Schiff, director of the Center for Liver Diseases at the University of Miami School of Medicine. Symptoms can last from several weeks to several months. But the illness is rarely fatal. In the United States, about 100 people, mainly elderly and people with underlying liver disease, die from complications each year, says Dr. Schiff.
Transmission. In this country, hepatitis A often makes headlines following an outbreak in a restaurant, usually traced to an infected food handler. Problems also arise in child care centers, where soiled diapers may not be handled properly. The virus can survive in raw or undercooked shellfish harvested from waters contaminated by raw sewage. Fruits and vegetables that are irrigated with contaminated water or handled improperly sometimes are culprits. In 1997, more than 200 Michigan schoolchildren were infected with hepatitis A after eating a batch of contaminated frozen strawberries.
Treatment. There is none. An infected person must wait for the disease to run its course. But the good news is that the virus never leads to chronic disease. Once cleared from the system, it causes no long-term liver damage and it cannot be contracted again.
A safe, effective vaccine has recently been developed. The vaccine -- believed to offer protection for at least 20 years -- is recommended for high-risk patients over age 2. This includes travelers bound for underdeveloped countries, gay men, intravenous drug users, and people who have chronic liver disease.
For those exposed to hepatitis A virus, a prompt dose of the immune globulin will likely stave off illness. The plasma substance contains antibodies that provide temporary protection -- at least three months -- if given within two weeks of exposure.
Hepatitis B is caused by a virus found in blood and body fluids. (Unlike hepatitis A, it's not spread in food or water.) The virus frequently causes flulike symptoms, produces dark urine, and may cause jaundice.
Each year, about 200,000 people in the United States get hepatitis B. About 95 percent of adults, whether or not they suffer symptoms, clear the virus from their bodies on their own and recover fully without later problems, says Dr. Raymond Koff, professor of medicine at the University of Massachusetts Medical School. The remaining small percentage develop chronic hepatitis because they can't knock out the virus.
More than 1 million Americans are estimated to have chronic hepatitis B, defined as an infection that lasts for more than six months. While patients may or may not feel sick, they can transmit the virus.
Transmission. It's probably spread most commonly through unprotected sex, says Dr. Koff. It's also transmitted through direct contact with infected blood, says Dr. Bruce Bacon, director of gastroenterology and hepatology at Saint Louis University Medical Center. Highly infectious, the virus can be spread through minute amounts of blood. Sharp instruments used in tattooing, body piercing, and acupuncture pose risk. Even small amounts of dried blood on razors, toothbrushes, and other personal-care items can carry the virus, says Dr. Bacon.
Treatment. There is no cure for hepatitis B. Drug therapy is prescribed for patients with advancing disease. The only FDA-approved treatment is alpha interferon, a drug that boosts the body's immune response. However, interferon is effective in only 35 percent of cases, and many patients suffer serious flulike side effects, depression, and thinning hair.
A safe, effective vaccine has been available since the 1980s. The CDC recommends the vaccination as part of a standard series of immunization shots that children get early, beginning right after birth. It also recommends that high-risk adults -- those who use intravenous drugs or have multiple sexual partners -- be vaccinated.
For decades, medical experts have known there was a virus responsible for many non-A, non-B hepatitis cases. They didn't identify it until 1989 and weren't able to develop a high-quality blood test to screen for it until 1992.
Today, medical authorities call hepatitis C an epidemic. Almost 4 million Americans have chronic hepatitis C, which is now the leading reason for liver transplants. It is associated with 10,000 deaths a year, a number that could triple in two decades unless people are identified and treated, says Dr. Margolis.
Transmission. Like hepatitis B, hepatitis C is spread by blood and body fluids, although sexual contact isn't a major route. Typically, it infects people without causing severe symptoms, says Dr. Margolis. In three out of four cases, symptoms are absent. Most others experience mild flulike symptoms.
The reason hepatitis C is such a major threat is because it usually leads to chronic infection. About 85 percent of infected people go on to develop chronic hepatitis, he says. They may feel well, but over the years, the virus slowly attacks the liver and may progress to serious liver disease.
About 290,000 Americans contracted the virus from blood transfusions given before 1992, according to the CDC. Since then, transfusion-related cases have been very rare.
Treatment. There is no cure and no vaccine. Drug therapy is only moderately successful. Currently, doctors use alpha interferon to suppress the virus.
In late 1998 the FDA approved Rebetron, a combination of interferon and an antiviral drug, ribavirin. In studies of patients who relapsed after using interferon alone, Rebetron knocked out the virus in 45 percent of cases. But it costs between $6,000 and $8,500 and causes serious side effects, including birth defects.