Hepatitis A is one of five human hepatitis viruses (hepatitis A, B, C, D, and E) that primarily infect the liver and cause illness. An estimated 80,000 cases occur each year in the U.S., although much higher estimates have been proposed based on mathematical modeling of the past incidence of infection. Each year, an estimated 100 persons die as a result of acute liver failure in the U.S. due to hepatitis A, but the rate of infection has dramatically decreased since the hepatitis A vaccine was licensed and became available in the U.S. in 1995.
Hepatitis A is a communicable (or contagious) disease that spreads from person-to-person. It is spread almost exclusively through fecal-oral contact, generally from person-to-person, or via contaminated food or water. Food contaminated with the virus is the most common vehicle transmitting hepatitis A. The food preparer or cook is the individual most often contaminating the food, although he or she is generally not ill at the time of food preparation. The peak time of infectivity, when the most virus is present in the stool of an infectious individual, is during the two weeks before illness begins. Although only a small percentage of hepatitis A infections is associated with foodborne transmission, foodborne outbreaks have been increasingly implicated as a significant source of hepatitis A infection.
Hepatitis A may also be spread by household contact among families or roommates, sexual contact, ingestion of contaminated water, ingestion of raw or undercooked fruits and vegetables or shellfish (like oysters), and from persons sharing illicit drugs. Children often have asymptomatic or unrecognized infections and can pass the virus through ordinary play to family members and other children and adults.
Symptoms of hepatitis A infection
Hepatitis A infection may cause no symptoms at all when it is contracted, especially in children. Such individuals will only know they were infected (and have become immune -- you can only get hepatitis A once) by getting a blood test later in life. The incubation period (from exposure to onset of symptoms) is 15-50 days, with an average of 30 days. Many children and most adults will experience the sudden onset of flu-like symptoms. After a day or two of muscle aches, headache, anorexia (loss of appetite), abdominal discomfort, fever and malaise, jaundice (also termed "icterus") sets in. Jaundice is a yellowing of the skin, eyes and mucous membranes that occurs because bile flows poorly through the liver and backs up into the blood. The urine will turn dark with bile and the stool will be light or clay-colored from lack of bile. When jaundice sets in, the initial symptoms begin to subside.
In general, the period of acute illness lasts from 10 days to three weeks, at which time affected individuals tend to recapture some sense of wellness. It is not unusual for blood tests to remain abnormal for six months (or more), prolonging recovery for up to a year. Most affected individuals show complete recovery within three to six months of the onset of illness. Relapse is possible, and although more common in children, it does occur with some regularity in adults.
Diagnosis and treatment of hepatitis A
There are blood tests widely available to accurately diagnose hepatitis A; blood samples are tested for hepatitis antibodies, which are present when the immune system responds to the hepatitis virus. Antibodies of the immune globulin (Ig) M variety, which indicate acute disease, and IgG antibodies, which stay positive for life, should both be measured.
Hepatitis A infection is an acute self-limiting disease. There is no specific treatment; treatment and management is merely supportive. The liver function tests generally improve as the affected individual begins to feel better. It is therefore well-accepted that the need for rest is best determined by the person's own perception of the severity of fatigue or malaise.
Preventing hepatitis A infection
Hepatitis A infection is totally preventable. Ill food-handlers should be excluded from work. Commercial food workers and other individuals who prepare food for others must always wash their hands with soap and water after using the bathroom, changing a diaper, and before preparing food. Cooking food to a temperature of 185 degrees F or higher will inactivate hepatitis A.
After a known exposure to hepatitis A, administration of a shot of immune globulin should be considered. If administered within two weeks of the exposure, it will usually be effective in preventing or at least ameliorating the disease.
Hepatitis A vaccine is the best protection from hepatitis A infection. The vaccine is recommended for persons traveling to areas with increased rates of hepatitis A, men who have sex with men, injecting and non-injecting drug users, persons with blood clotting factor disorders (such as hemophilia), persons with chronic liver disease, and children living in regions of the U.S. with increased rates of hepatitis A. The vaccine may also help protect household contacts of those with hepatitis A infection. Vaccination of food handlers would likely substantially diminish the incidence of hepatitis A outbreaks. The vaccine is licensed for individuals aged two and older, but there is good evidence that the vaccine is safe and effective at one year of age.
