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Hepatitis A

Hepatitis A

  • 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
Signs and symptoms

  • The preicteric phase brings nonspecific influenza-like symptoms consisting of anorexia, nausea, fatigue, and malaise
  • Abrupt onset of anorexia, nausea, vomiting, malaise, fever, headache, and right upper quadrant abdominal pain with acute illness
  • Icteric hepatitis is generally accompanied by dark urine, acholic (light-colored) stools, and worsening of systemic symptoms
  • Pruritus is often a major complaint of icteric patients
    Physical examination
  • Icteric sclera, skin, and secretions
  • Mild weight loss of 2 to 5 kg
  • Hepatomegaly
    Laboratory tests
  • Positive serum IgM anti-hepatitis A
  • Mild elevations of serum bilirubin, Оі-globulin, and hepatic transaminase (alanine transaminase [alanine transaminase], and aspartate transaminase [aspartate transaminase] values to about twice normal in acute anicteric disease
  • Elevations of alkaline phosphatase, Оі-glutamyl transferase, and total bilirubin in patients with cholestatic illness
  • 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.

Treatment

  • 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.

Prevention

  • 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
Children living in states, counties, or communities where rates of hepatitis A are at least twice the national average (≥20 cases per 100,000 population). For 1987– 1997, these states included Arizona, Alaska, Oregon, New Mexico, Utah, Washington, Oklahoma, South Dakota, Idaho, Nevada, and California.
Children living in states, counties, or communities where rates of hepatitis A are greater than the national average but lower than twice the national average should be considered for routine vaccination (≥10 cases but <20 cases per 100,000 population). For 1987– 1997, these states included Missouri, Texas, Colorado, Arkansas, Montana, and Wyoming.
Persons traveling to or working in countries that have high or intermediate endemicity of infection.a
Men who have sex with men.
Illegal-drug users.
Persons who have occupational risk for infection (e.g., persons who work with hepatitis A-infected primates or hepatitis A in a research laboratory setting).
Persons who have clotting-factor disorders.
Persons who have chronic liver disease (e.g., persons with chronic liver disease caused by hepatitis B or C and persons awaiting liver transplants).
aTravelers to Canada, Western Europe, Japan, Australia, or New Zealand are at no greater risk for hepatitis A infection than they are while in the United States. All other travelers should be assessed for hepatitis A risk.
From Centers for Disease Control.2
  • 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.

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