Hepatitis A infection is one of the most frequently reported vaccine-preventable diseases in the United States.
The incidence of hepatitis A correlates directly with poor sanitary conditions and hygienic practices. Hepatitis A infection occurs primarily from person-to-person transmission.
Hepatitis A infection usually produces a self-limited disease with a low case-fatality rate. The disease may last up to 6 months in three phases: incubation, acute hepatitis, and convalescence. Most patients have full clinical and biochemical recovery within 12 weeks.
The minimal degree of liver cell damage with hepatitis A is reflected by mild elevations of serum transaminases values to about twice normal.
The clinical presentation of hepatitis A infection. The average incubation period is 28 days, with a range of 15 to 50 days.
No cases of a chronic carrier state or chronic hepatitis have been reported with hepatitis A.
|TABLE. Clinical Presentation of Acute Hepatitis A|
The diagnosis of acute hepatitis A infection depends on clinical suspicion, characteristic symptoms, elevated aminotransferases and bilirubin, and a positive anti-hepatitis A IgM. The antibody peaks during the early phase of convalescence and remains positive for 4 to 6 months after the onset of the disease.
Management of hepatitis A infection is primarily supportive, including a healthy diet, rest, maintenance of fluid balance, avoidance of hepatotoxic drugs and alcohol.
Pharmacologic agents offer no clear benefit in the treatment of hepatitis A.
The spread of hepatitis A can be best controlled by avoiding exposure. The most important measures to avoid exposure include good hand-washing techniques and good personal hygiene practices.
The current vaccination strategy in the United States includes vaccinating: (1) children in states, counties, and communities with consistently elevated rates of hepatitis A, (2) persons in groups at increased risk for hepatitis A infections, such as international travelers, and (3) persons at risk of adverse outcomes, such as those with chronic liver disease.
Hepatitis A vaccines given preexposure demonstrate protective efficacy in 94% to 100% of vaccines within 1 month after primary vaccination. When a booster dose is given 6 months later, essentially 100% of recipients develop high antibody levels.
Immunization is indicated for individuals aged 2 years or older who are at increased risk of hepatitis A infection. Groups who should receive hepatitis A vaccine are shown in Table 24-2. Approved dosing recommendations are shown in Table 24-3.
Prevention of hepatitis A has traditionally focused on avoiding exposure as well as preexposure and postexposure prophylaxis with IG.
A single dose of IG of 0.02 mL/kg intramuscularly is recommended for travelers to high-risk areas if travel is for less than 3 months. For lengthy stays, 0.06 mL/kg intramuscularly should be given every 3 to 5 months. Dosing is the same for adults and children.
|TABLE. Groups at Increased Risk of Hepatitis A and Recommended for Preexposure Hepatitis A Vaccination|
The postexposure prophylactic benefit from IG is greatest early in the incubation period and is of no benefit more than 2 weeks after exposure. A single IG dose of 0.02 mL/kg intramuscularly is used for postexposure prophylaxis of hepatitis A.
The vaccines are known to produce protective levels of antibody for at least 5 to 8 years.
Vaccine side effects include injection site reactions and headache.