Hepatitis is Latin for "inflammation of the liver". The liver does several things in our bodies, including storing and releasing glucose to keep your blood sugar constant and getting rid of many useless and harmful chemicals including drugs, food breakdown byproducts, and breakdown products of old blood cells. If the liver can't function, one of the first signs is jaundice, as bilirubin (breakdown product of hemoglobin from old blood cells) accumulates in your body and makes you turn yellow. There are many things, including drugs, that can cause liver inflammation or malfunction. There are several viruses which do little more than cause liver damage, but the damage they do is serious. Fortunately we now have vaccines for the two most common hepatitis viruses: hepatitis A and hepatitis B.
Hepatitis A is commonly found in feces (stools) of infected persons, and is usually transmitted by something politely termed "fecal-oral contact". This is not to imply that people deliberately eat the stools of infected persons: unfortunately, an infected person who is careless about hygiene can carry the virus on hands and fingers -- and transfer the virus to food and drink -- and in areas with poor sanitation the virus can sometimes be found in drinking water during an outbreak. (This does not happen very often in the United States, or in other countries with pretreated municipal water supplies, but in some less-developed areas fecal contamination of drinking water is a big problem.) The virus can also be left on toilet seats by an infected person, and can infect others through that route.
Hepatitis A is not particularly common in the United States, mainly because of our sanitation and water-purification procedures. It has appeared occasionally, though, usually when someone infected while travelling transmits the virus to others. Often the "index patient" is a food handler and deposits the virus on foods in preparation, or a particular shipment of a particular food was grown in an area with contaminated water and the virus was left on the surface of the plant. In these cases public-health investigators find that all of the new cases are people who ate food from or at a particular place.
We can now vaccinate against the hepatitis A virus; two doses given at least six months apart appear to give lifelong protection. Children must be at least 1 year old to respond well to the vaccine. Immune globulin from previously infected persons can be given to those who are not immune and have been exposed to the virus or must travel to an area where many people have hepatitis A. The passive immunity provided by the immune globulin only lasts for a few months.
Hepatitis B is generally transmitted by blood and body fluids. Until we were able to test for the virus itself, hepatitis B was a common complication of blood transfusion; nowadays every unit of blood used for transfusion is tested for hepatitis B, and blood containing the virus is destroyed without being used. (Note: you cannot get hepatitis B by giving blood -- only by receiving it.) However, hepatitis B can also be transmitted by other body fluids, and in particular by sexual contact.
Hepatitis B infections typically start several months after exposure to the virus, and can produce mild symptoms in some people. In others it can cause life-threatening liver damage. Some people cannot fight off the infections completely and become "chronic carriers" of the virus; these people can later develop cancer of the liver due to damage caused by the virus.
The original hepatitis B vaccines were produced using blood from people who had hepatitis B in the past. Today's vaccines are made using recombinant DNA techniques, using brewers' yeast as the base cells for production, and contain no human or animal blood products. The vaccine gives immunity no matter how old you are; many pediatricians give the first dose to newborn babies before they leave the hospital with their mothers. Some babies -- those whose mothers are carriers of the hepatitis B virus -- must have their first dose of hepatitis B vaccine within 12 hours of birth, along with a dose of hepatitis B immune globulin. There have been cases in which babies whose mothers were hepatitis B carriers and did not receive the vaccine and immune globulin died from hepatitis B infection. Because of this, some states (Michigan, where I practice, is one) provide hepatitis B vaccine for all newborns and supply hospitals with the vaccine so that every newborn can receive the first dose of vaccine before going home after birth.
You need to have three doses of the vaccine for complete protection from hepatitis B: the second dose is usually given 1-2 months after the first dose, while the third is given 6-12 months after the first. These intervals between doses are not absolutely necessary -- except for babies of hepatitis B carriers, who must receive their second and third doses on time -- but the second dose usually has to be given no sooner than 1 month after the first dose, and the third dose should be given at least 2 months after the second (and at least 6 months after the first dose). Just to confuse people more... one of the two hepatitis B vaccines on the market can be given at birth, 1 month, and 2 months -- but if the third dose is given at 2 months the patient has to receive a fourth dose at age 18 months. I do not know of any pediatricians who use this schedule, except for children who are very likely to be exposed to hepatitis B; even children of hepatitis B carriers can receive three doses of vaccine if it is done on the recommended "0 month-1 month-6 month" schedule. There is also a two-dose schedule for one of the two vaccines that is being used in 11- to 15-year old children. used in adolescents.
There are two situations in which hepatitis B vaccine should be given before age 6 months.
And to make matters even more confusing, the rules are a bit different for
premature babies. Premies born to mothers who are known hepatitis B carriers
should still receive the vaccine immediately after birth. However, they
should receive another three doses, starting at 1 month of age.
Premies whose moms are hepatitis B negative may wait until they are a month
old to get their first dose of vaccine. The best advice I can give, as
always: ask your baby's doctor when to give the vaccine.
Infection with hepatitis C has exactly the same symptoms and signs as do hepatitis A or B infections. Most hepatitis C infections tend not to have any symptoms, and those symptoms that are seen are often mild and insidious (they come on very gradually). Like hepatitis B, hepatitis C is spread by body-fluid contact; most people with hepatitis C received blood from infected donors or are drug abusers. The risk of getting hepatitis C from sexual contact is lower than it is with hepatitis B, but it still happens. Like hepatitis B, hepatitis C can lead to liver cirrhosis (breakdown of liver tissue -- cirrhosis occurs most famously in alcoholics, but can also happen with viral hepatitis) and/or to liver cancer.
Unfortunately, there is no vaccine yet for hepatitis C, nor is there an immune globulin to provide passive immunity. Treatment with interferon and ribavirin can help some adults with hepatitis C, and may be useful in children as well.
Hepatitis D can be thought of as an incomplete virus: it needs help from the hepatitis B virus in order to cause liver infection. However, simultaneous infection with the two viruses may cause more severe disease than does hepatitis B by itself: the hepatitis D virus can turn a mild chronic hepatitis B infection into a much more severe infection. There is no specific treatment yet for hepatitis D, but since hepatitis D cannot infect someone who does not have hepatitis B we can prevent hepatitis D infection by immunizing against hepatitis B.
Hepatitis E, like hepatitis A, is passed from person to person by fecal-oral contact. Hepatitis E has most often been seen in epidemics in parts of Mexico, Asia, and Africa; it is occasionally seen in the United States, but usually in people who have travelled to places where hepatitis E is common. Hepatitis E is seen much more often in adults than in children, and pregnant women are particularly likely to die of hepatitis E infection. There is no specific treatment other than supportive care. The best way to prevent hepatitis E infection is good hygiene and avoiding food or water which may be contaminated.
There are several other, less common, viruses that cause hepatitis. For more information on hepatitis, including information on current outbreaks, check the Hepatitis Branch Home Page at the Centers for Disease Control and Prevention.
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