Hepatitis A is the only common vaccine-preventable foodborne disease in the United States. Hepatitis A may cause no symptoms at all when it is contracted, especially in children. Asymptomatic individuals will only know they were infected (and have become immune, given that you can only get hepatitis A once) by getting a blood test later in life. Approximately 10 to 12 days after exposure, HAV is present in blood and is excreted via the biliary system into the feces. Although the virus is present in the blood, its concentration is much higher in feces. HAV excretion begins to decline at the onset of clinical illness and decreases significantly by 7 to 10 days after onset of symptoms. Most infected persons no longer excrete virus in the feces by the third week of illness; children may excrete HAV longer than adults.
Seventy percent of hepatitis A infections in children younger than six years of age are asymptomatic; in older children and adults, infection tends to be symptomatic with more than 70% of those infected developing jaundice. Symptoms typically begin about 28 days after contracting HAV but can begin as early as 15 days or as late as 50 days after exposure. The symptoms include muscle aches, headache, anorexia (loss of appetite), abdominal discomfort, fever, and malaise.
After a few days of typical symptoms, 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 also turn dark with bile and the stool light or clay-colored from lack of bile. When jaundice sets in, initial symptoms such as fever and headache begin to subside.
In general, symptoms usually last less than 2 months, although 10% to 15% of symptomatic persons have prolonged or relapsing disease for up to 6 months. It is not unusual, however, for blood tests to remain abnormal for six months or more. The jaundice so commonly associated with hepatitis A can also linger for a prolonged period in some infected persons—sometimes as long as eight months or more. Additionally, pruritus, or severe “itchiness” of the skin, can persist for several months after the onset of symptoms. These conditions are frequently accompanied by diarrhea, anorexia, and fatigue.
Relapse is possible with hepatitis A, typically within three months of the initial onset of symptoms. Although relapse is more common in children, it does occur with some regularity in adults. Most persons who are infected with hepatitis A fully recover, and do not develop chronic hepatitis. Persons do not carry hepatitis A long-term as with hepatitis B and C.
Fulminant hepatitis A is a rare but devastating complication of HAV infection. As many as 50% of individuals with acute liver failure may die or require emergency liver transplantation. Elderly patients and patients with chronic liver disease are at higher risk for fulminant hepatitis A. In parallel with a declining incidence of acute HAV infection in the general population, however, the incidence of fulminant HAV appears to be decreasing.