Hepatitis A is a viral infection that multiplies only in the liver cells and the lining of the gastrointestinal tract. Hepatitis A is a hardy virus that may survive for several months in sea water, fresh water, waste water and the soil. It is resistant to freezing and may be spread in ice cubes.
Infection occurs primarily from close person to person contact via hands or sexual contacts. Ingestion of contaminated food is a common source of Hepatitis A outbreaks. The potential spread by intravenous substance use or blood transfusion is believed to be extremely low. The incubation period is 15 to 50 days with an average of 25 to 30 days. Approximately 70% of infected adults will develop symptoms such as jaundice, nausea and vomiting. However, only about 30 % of infected children will develop symptoms. The problem is that these asymptomatic individuals will shed the virus and continue to spread the disease. Children may shed the virus in their stools for up to 6 months. This is often a major factor that perpetuates community wide outbreaks.
Due to childhood immunization practices the number of reported cases of Hepatitis A has dropped from 32,000 in 1990 to 7,700 in 2003. Childhood vaccination and vaccination of higher risk groups including close personal contacts with an infected person, bisexuals, gay males, travelers outside the USA and intravenous substance abusers could markedly reduce the remaining 7,700 cases in the United States.
The main signs and symptoms of Hepatitis A are abrupt onset of fever, malaise, decreased appetite, nausea, vomiting, abdominal pain and headache. Occasionally individuals manifest muscle aches, diarrhea, joint aches, cough, hives or intense itching. Physical signs include a tender swollen liver, a tender swollen spleen, tender swollen lymph nodes and jaundice. About 10 – 20% of Hepatitis A infections will develop a prolonged relapsing course that may last several months. Approximately 1% of adults with the infection will develop fulminant liver failure. The overall fatality rate is low but does approach 2% in adults over the age of 40.
There is no specific treatment for Hepatitis A. Treatment is supportive and includes rest, adequate nutrition and avoidance of agents toxic to the liver such as alcohol and Tylenol. Caregivers and close contacts should be given the Hepatitis A vaccine (a series of 2 vaccinations, given 6 or more months apart) and immune globulin if not already fully vaccinated. Administration of immune globulin is not contraindicated in pregnancy or while breast feeding.
Mark Smith, MD