I recovered from acute hepatitis B about two months ago. How long would it take for my body to form the antibody? Would three months be enough? Is there any chance I will have this illness again in the future? Is there any special kind of diet I should follow? How much activity am I allowed to endure? I am a very busy college student.

A.T.

Hepatitis B is a viral infection of the liver. It occurs throughout the world and is most commonly transmitted by unprotected sex with an infected partner, by exposure to contaminated blood (such as among people who share needles used for injecting drugs) or from an infected mother to her baby around the time of birth. There are other means of transmission, but these three are by far the most common ways in which the hepatitis B virus (HBV) is spread. In about two-thirds of cases, the infected person has no symptoms, or at least none that specifically suggest hepatitis. In cases where the patient does experience symptoms, typical acute hepatitis (liver inflammation) develops about one to four months after infection. Symptoms include fatigue, muscle aches, anorexia (loss of appetite), nausea, pain in the upper right part of the abdomen and jaundice (yellowing of the skin and eyes).

Less than 1 percent of people infected with hepatitis B develop fulminant (sudden and severe) disease, which can cause liver failure, leading to death or the need for liver transplantation. In patients with non-fulminant disease, most symptoms usually resolve in one or two months. However, fatigue, a very prominent complaint in hepatitis B, can persist for months longer. In less than 10 percent of adults infected with HBV, the virus is not cleared and chronic (persistent) hepatitis develops. These patients are at risk of passing the virus to others, as well as developing cirrhosis (scarring of liver tissue) and liver cancer.

In patients who clear their infection (as it sounds like you have), liver tests become normal after a few months. The virus is cleared from the blood during that time, as well. (High-tech testing can sometimes detect minute levels of virus, but this finding probably is meaningless.) Soon thereafter, antibody to the virus appears in the blood. This antibody protects against future infection. In fact, this same antibody is present in people vaccinated against hepatitis B infection and is responsible for the immunity that the vaccine confers.

There is no specific therapy for acute hepatitis B. In the past, patients were told that exercise -- even walking -- could lead to problems, but studies have not confirmed this. Today, physicians generally recommend that patients undertake only very light exercise and slowly increase their general activity, as tolerated. I would say that you can go back to classes when you feel able, but would advise avoiding for a few months any sports or exercise other than walking. Once you feel up to it, you can slowly increase your activity. There are no dietary factors that have been shown to be of benefit. You also should know that until the virus clears from the blood, you are at risk of spreading the infection to others. Three to six months after you became ill, you can have a blood test to check whether you have cleared the virus from your body. If you do clear the virus initially, you are at essentially no risk of having problems in the future.