Hepatitis A

Introduction

• HAV infection usually produces a self-limited disease and acute viral infection, with a low fatality rate, and confers lifelong immunity. International travel is a major risk factor for infection.
• HAV infection primarily occurs through transmission by the fecal-oral route, person-to-person, or by ingestion of contaminated food or water. The incidence of HAV correlates directly with low socioeconomic status, poor sanitary conditions, and overcrowding. Rates of HAV infection have increased among international travelers, injection drug users, and men who have sex with men.
• The disease exhibits three phases: incubation (averaging 28 days, range 15–50 days), acute hepatitis (generally lasting 2 months), and convalescence. Most patients have full clinical and biochemical recovery within 12 weeks. Nearly all individuals will have clinical resolution within 6 months of the infection. HAV does not lead to chronic infection.

Clinical Presentation of Acute Hepatitis A

Signs and symptoms

• The preicteric phase bring 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 2–5 kg
• Hepatomegaly

Laboratory tests

• Positive serum immunoglobulin M anti–hepatitis A virus
• Mild elevations of serum bilirubin, γ-globulin, and hepatic transaminase (ALT [alanine transaminase] and aspartate transaminase [AST]) values to about twice normal in acute anicteric disease
• Elevations of alkaline phosphatase, γ-glutamyl transferase, and total bilirubin in patients with cholestatic illness.

TREATMENT

• Goals of Treatment: Complete clinical resolution, including avoidance of complications, normalization of liver function, and reduction of infectivity and transmission. No specific treatment options exist for HAV. Management of HAV infection is primarily supportive. Steroid use is not recommended.

PREVENTION : The spread of HAV can be best controlled by avoiding exposure. The most important measures to avoid exposure include good handwashing techniques and good personal hygiene practices.

• The current vaccination strategy in the United States includes vaccinating all children at 1 year of age.
• Three inactivated virus vaccines are currently licensed in the United States: Havrix, Vaqta, and Twinrix. Seroconversion rates of 94% or greater are achieved with the first dose.
• IG is used when pre- or postexposure prophylaxis against HAV infection is needed in persons for whom vaccination is not an option. It is most effective if given during the incubation phase of infection. A single dose of IG of 0.02 mL/kg is given intramuscularly for postexposure prophylaxis or short-term (≤5 months) preexposure prophylaxis. For lengthy stays, a single dose of 0.06 mL/kg is used. HAV vaccine may also be given with IG.
• For people recently exposed to HAV and not previously vaccinated, IG is indicated for ✓ Those in close contact with an HAV-infected person; all staff and attendees of daycare centers when HAV is documented; those involved in a common source exposure (e.g., a food-borne outbreak); classroom contacts of an index case patient; and schools, hospitals, and work settings where close personal contact occurred with the case patient.

Recommendations for Hepatitis A Vaccination

All children at 1 year of age, Children and adolescents ages 2–18 years who live in states or communities where routine hepatitis A vaccination has been implemented because of high disease incidence, Persons traveling to or working in countries that have high or intermediate endemicity of infection, Men who have sex with men, Illegal-drug users, Persons who have occupational risk for infection (e.g., persons who work with HAV-infected primates or HAV 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), All previously unvaccinated persons anticipating close personal contact (e.g., household contact or regular babysitter) with an international adoptee from a country of high or intermediate endemicity within the first 60 days following the arrival of the adoptee.

Recommended Dosing of Hepatitis A Vaccines

Vaccine Vaccinee’s Age (years) Dose Number of Doses Schedule (months)Havrix 1–18 720 ELISA units 2 0, 6–12≥19 1440 ELISA units 2 0, 6–12Vaqta 1–18 25 units 2 0, 6–18≥19 50 units 2 0, 6–18Twinrix >18 20 ELISA units 3 0,1,6 >18 720 ELISA units 4