Hepatitis A is an infection primarily affecting the liver caused by the hepatitis A virus (HAV), a nonenveloped RNA virus that is classified as a picornavirus.
Subsequent symptoms: One to seven days after initial symptoms jaundice (yellowing of the skin and sclera), dark urine and clay-colored stool may occur. Among older children and adults, infection is typically symptomatic, with jaundice occurring in > 70 % of patients. The duration of a typical course of hepatitis A is 2 – 6 weeks.
Complications: may involve a prolonged, relapsing hepatitis, which can occur for up to one year. Relapsing hepatitis occurs in about 15% of cases. Hepatitis A is rarely fatal and has no chronic carrier state. The elderly and persons with chronic liver disease are at greater risk of fulminant (rapid and severe) hepatitis A. The greatest morbidity and mortality occurs in person greater than 50 years old. Hepatitis A is clinically indistinguishable from other types of hepatitis. It must be diagnosed through laboratory testing for hepatitis A IgM.
Humans with active infections (symptomatic or not) are the only natural reservoir for this disease. It is rarely found in chimpanzees or other primates.
The primary modes of transmission are direct or indirect person-to-person spread via the fecal-oral route, including sexual contact, or ingestion of contaminated food or water. Transmission occurs most frequently among close contacts, especially in households and extended family settings. Virtually any food can be involved including ready-to-eat or uncooked food (sandwiches, salads, ice cream, strawberries, etc.), which can become contaminated by an infected food worker with poor hygiene; inadequate treatment of stool-contaminated drinking water (a rare source of hepatitis A in Iowa); contaminated produce (such as lettuce or strawberries irrigated or processed with contaminated water); or shellfish harvested from fecally contaminated waters and then consumed raw or undercooked. The foods most commonly contaminated are raw, wet, and rough, such as lettuce and ice. Because the virus is present in blood during the illness prodrome, HAV has been transmitted on rare occasions by blood transfusion. Hepatitis A has been transmitted among drug users by fecally contaminating drug paraphernalia that is being shared.
The incubation period for hepatitis A ranges from 15 -50 days, with an average of 28 - 30 days. The incubation period may be shorter with a greater hepatitis A virus (HAV) dose.
Individuals are usually most infectious from 1 week before their symptoms begin to several days after onset of jaundice. Viral shedding in the stool is greatest during the week before symptom onset, until several days after onset. Virus excretion begins to decline at the onset of clinical illness, and has decreased significantly 7 – 10 days after onset of symptoms. If diarrhea exists, the patient’s ability to transmit the virus is greatly enhanced. HAV infection provides lifelong immunity.
For public health intervention, a case is considered to be potentially infectious from 14 days before the onset of symptoms to 7 days after onset of symptoms. However, prolonged viral excretion (up to 6 months) has been documented in infants and children. Chronic shedding of HAV in feces does not occur.
Hepatitis A has a worldwide distribution and occurs as sporadic cases and outbreaks. In countries where sanitation is poor, infection is common and occurs at an early age. Adults, therefore, are usually immune and outbreaks are uncommon. In developed countries, disease transmission is a problem in child care settings with diapered children, among household and sexual contacts of acute cases, among travelers to countries where the disease is common, and among the institutionalized. In some situations drug users can be at high risk.
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2006 Red Book: Report of the Committee on Infectious Diseases, 27th Edition. Illinois, American Academy of Pediatrics, 2006.
CDC. 2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings, June 2007
CDC. Prevention of Hepatitis A through Active or Passive Immunization. MMWR. May 19, 2006 / 55(RR07);1-23.
CDC. Update: Prevention of Hepatitis A After Exposure to Hepatitis A Virus and in International Travelers. Updated Recommendations of the Advisory Committee on Immunization Practices (ACIP), MMWR, October 19, 2007 / 56(41);1080-1084
Heymann, D.L., ed., Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.