Definition
A.Hepatitis A is an acute self-limited illness with inflammation of the liver caused by a viral infection. Hepatitis A virus (HAV) is spread by viral shedding. Acute cases of hepatitis A are reportable to the public health department.
B.Case definition: An acute illness with a discrete onset of any sign or symptoms consistent with acute viral hepatitis (e.g., fever, headache, malaise, anorexia, nausea, vomiting, diarrhea, and abdominal pain) AND either jaundice or elevated serum alanine aminotransferase (ALT) or AST levels.
C.The average incubation period is 28 days (range 15–50 days).
D.The highest titers of HAV in the stool of infected patients occur 1 to 2 weeks before onset of illness (jaundice or elevation of liver enzymes), during which time patients are most likely to transmit infection. Risk subsequently diminishes and is minimal in the week after onset of jaundice. Up to 70% of patients will have jaundice. Persons with chronic liver disease (CLD) are at risk for fulminant hepatitis.
E.Duration of HAV infection is typically 8 weeks, but prolonged disease, as long as 6 months, can occur in 10% to 15% of symptomatic patients.
F.The major methods of prevention include improved sanitation of water sources, improved hygiene practice prior to food preparation and diaper changes, immunization with the hepatitis A vaccine, and administration of immune globulin (IG).
G.Hepatitis A does not reoccur because immunoglobulin G (IgG) antibodies to HAV provide lifelong protection.
Incidence
A.From 30% to 35% of acute hepatitis cases in the United States are due to HAV. In developing countries, where infection is endemic, most people are infected during the first decade of life. Multistate HAV outbreaks have recently occurred in the United States:
1.August 2016—Hawaii, linked to raw scallops.
2.August 2016—multiple states, linked to frozen strawberries.
3.March 2017 to 2018—multiple states among people who used drugs and/or people who are homeless.
B.Outbreak in custodial institutions accounts for about 10% to 15% of reported HAV in the United States.
C.The incidence of mortality from HAV is 0% to 2%. The single most important determinant of illness severity is age; a direct correlation between increasing age and the likelihood of adverse events is present. Most deaths from acute HAV occur in persons older than 50 years.
Pathogenesis
A.HAV is a small, RNA enterovirus classified as a member of the picornavirus group. Viral replication depends on hepatocyte uptake and synthesis, and assembly occurs exclusively in liver cells. Transmission of HAV is person-to-person, primarily by the fecal–oral route and parenterally. The incubation period is 15 to 50 days, with an average of 25 to 30 days.
B.Common-source, food- and waterborne epidemics have occurred, including several caused by shellfish contaminated with human sewage. Nosocomial outbreaks have occurred as a result of shedding of HAV from infected, asymptomatic neonates, children, or adults.
Predisposing Factors
A.Primarily, infections in the United States result from travel to another country where HAV transmission is common.
B.Person-to-person transmission contact through the fecal–oral route:
1.Contact with a child who attends a child care center (especially with children in diapers).
2.Sex among men who have sex with men (MSM).
3.Vertical transmission from mother to fetus (limited).
4.Personal contact with a newly arriving international adoptees with high or intermediate hepatitis A endemicity.
5.Injection and noninjection drug users.
C.Exposure to contaminated food or water:
1.Uncooked foods contaminated with HAV.
2.Cooked foods that are not heated to temperatures that are capable of killing the virus.
3.Foods contaminated after cooking (infected food handlers).
4.Freezing does not inactivate HAV.
5.Waterborne outbreaks from poor sanitation. In the United States outbreaks of HAV caused by flooding have not been documented.
Common Complaints
A.Malaise.
B.Anorexia.
C.Nausea.
D.Low-grade fever.
E.Jaundice—icteric phase (70% of older children and adults):
1.Tea-colored urine.
2.Clay-colored stool.
3.Abdominal pain.
4.Pruritus.
5.Enlarged liver.
F.Fatigue.
G.Joint pain.
Other Signs and Symptoms
A.Adults: Severe, prolonged course with fatigue, headache, vomiting, and symptoms noted earlier.
B.Relapsing hepatitis A is more common in the elderly. There generally has been a protracted course of symptoms and a relapse of symptoms following an apparent resolution.
Subjective Data
A.Review duration, onset, and severity of symptoms, including specifics about urine or stool color changes.
B.Ask the patient about family members and sexual contacts with similar symptoms.
C.Review the patient’s history of blood transfusions, intravenous (IV) drug use, and alcohol abuse.
D.Inquire about occupational exposure.
E.Ask the patient about recent international travel or exposure to newly arrived international adoptees.
F.Review immunization status.
G.Review medications for a possible Tylenol overdose or ecstasy use as a cause for acute drug-induced liver injury.
Physical Examination
A.Check temperature (acute illness), pulse, respirations, blood pressure (BP), and weight.
B.Inspect:
1.Note general appearance.
2.Inspect the skin for slight jaundice or rash.
3.Inspect mucous membranes and nail beds.
4.Inspect eyes for yellow sclera.
C.Auscultate lung fields, all quadrants of the abdomen, and the heart.
D.Percuss the abdomen.
E.Palpate:
1.Palpate all quadrants of the abdomen for masses, liver tenderness, and hepatosplenomegaly (about 10% of cases).
Diagnostic Tests
Nucleic acid testing (NAT) is the gold standard for diagnosis of viremic stages of hepatitis infection.
A.Because the clinical characteristics are the same for all types of acute viral hepatitis, HAV must be confirmed by a positive serologic test for immunoglobulin M (IgM) antibody to hepatitis A virus (anti-HAV) or the case must meet the clinical case definition and occur in a person who has an epidemiologic link with a person who has laboratory-confirmed hepatitis A (i.e., household or sexual contact with an infected person during the 15 to 50 days before the onset of symptoms):
1.Serum IgM presents at onset of illness and disappears within 4 months, generally indicating current or recent infection. However, it may persist for 6 months or longer.
2.Presence of IgG anti-HAV antibodies without virus-specific IgM indicates past infection and immunity.
B.Liver function studies, including ALT, AST, lactate dehydrogenase (LDH), and alkaline phosphatase (ALP).
C.Bilirubin, direct and indirect.
D.Complete blood count (CBC).
E.Prothrombin time (PT).
F.Imaging studies are usually not indicated for hepatitis A infection. An ultrasound may be used to exclude other pathology.
Differential Diagnoses
A.HAV.
B.Mononucleosis.
C.Cancer.
D.Obstructive jaundice.
E.Alcoholic hepatitis or cirrhosis.
F.Hepatotoxic drug use:
1.Drug-induced liver injury (e.g., Tylenol, Ecstasy).
2.Drug-induced hypersensitivity reaction (e.g., sulfasalazine hypersensitivity).
G.Food poisoning.
H.Exclusion of other hepatitis types.
I.Cytomegalovirus (CMV).
J.Acute HIV infection.
Plan
A.General interventions:
1.Contact precautions are recommended for diapered and/or incontinent patients for 1 week after onset of symptoms.
2.Children and adults with acute HAV infection should be excluded from school, work, and child care centers for 1 week after onset of illness.
3.Hepatitis is self-limiting and does not require therapy. Treatment is supportive:
a.Limit activities secondary to malaise.
b.Alcohol consumption is not advised.
c.Adults who work as food handlers should not work for 1 week after onset of the illness.
4.Encourage strict handwashing.
B. 
See Section III: Patient Teaching Guide Jaundice and Hepatitis.
1.Teach the patient that major methods for prevention are improved sanitation (e.g., of water sources and in food preparation) and personal hygiene.
2.Food and travel precautions include the following:
a.Avoid uncontrolled water resources: Use bottled water, boil water, or add iodine to inactivate the virus.
b.Avoid raw shellfish.
c.Avoid uncooked foods.
d.All fruit should be washed and peeled.
3.HAV can be killed by cleaning with a freshly prepared solution of 1:100 dilution of bleach to water.
C.Dietary management: Encourage optimum nutrition.
D.Pharmaceutical therapy:
1.HAV vaccine preexposure is preferred in all populations unless contraindicated.
2.Immune globulin (IG; GamaSTAN S/D): Preexposure administration is 0.02 mL/kg, two doses IM.
3.Travel preexposure prophylaxis to endemic areas:
a.Up to 1 month of travel: 0.1 mL/kg.
b.Up to 2 months of travel: 0.2 mL/kg.
c.2 months of travel or longer: repeat dose of 0.2 mL/kg every 2 months.
4.Persons who have been exposed recently to hepatitis A virus (HAV) and who have not been vaccinated should be administered one dose of single-antigen hepatitis A vaccine or immune globulin (IG) as soon as possible, within 2 weeks after exposure:
a.Healthy persons aged ≥12 months who have been exposed to HAV within the prior 14 days and have not previously completed the 2-dose HepA vaccine series should receive a single dose of HepA vaccine as soon as possible. In addition to HepA vaccine, IG (0.1 mL/kg) may be administered to persons aged >40 years depending on the providers’ risk assessment. For long-term immunity, the HepA vaccine series should be completed with a second dose at least 6 months after the first dose; the second dose is not necessary for PEP.
b.Persons aged ≥12 months who are immuno-compromised and persons with chronic liver disease who have been exposed to HAV within the prior 14 days and have not previously completed the 2-dose HepA vaccine series should receive both IG (0.1 mL/kg) and HepA vaccine simultaneously in a different anatomical site as soon as possible after exposure. For long-term immunity, the HepA vaccine series should be completed with a second dose at least 6 months after the first dose; the second dose is not necessary for PEP.
c.For infants aged <12 months and persons for whom vaccine is contraindicated (who are allergic to a vaccine component) should receive IG (0.1 mL/kg) instead of vaccine as soon as possible and within 2 weeks after exposure.
d.Postexposure prophylaxis with IG is also recommended for the following:
i.Household and sexual contacts of infected persons.
ii.Newborn infants of HAV-infected mothers.
iii.Child care center staff, children, and their household contacts.
iv.Students when transmission within school is documented.
v.Staff in institutions and hospitals.
vi.People who ingested HAV-contaminated food or water within 2 weeks of last exposure.
5.Vaccines:
a.Two inactivated HAV vaccines, Havrix and Vaqta, are available in the United States.
b.Twinrix is a combination hepatitis A (Havrix) and hepatitis B (Engerix-B) vaccine available in the United States for ages 18 years or older (see Table 14.15).
6.HAV vaccine is recommended for the following:
a.Children 2 years and older in defined and circumscribed communities with high endemic rates and/or periodic outbreaks of HAV infection.
b.Patients with CLD.
c.Homosexual and bisexual men.
d.Users of injections and illicit drugs.
e.Those with occupational risk of exposure, such as handlers of nonhuman primates and persons working with HAV in a laboratory setting.