This 5-year-old male, who recently returned from a family trip to Mexico, presents
with one day of persistent abdominal pain, nausea, and vomiting. The physical
exam is significant for diffuse tenderness to palpation with focal worsening in the
right upper quadrant, and laboratory evaluation is significant for a marked elevation
in serum aminotransferases (e.g., ALT, AST). This clinical picture
indicates likely hepatitis A virus (HAV) infection.
HAV is a positive sense, single-stranded RNA virus of
the Picornaviridae family. The infection is transmitted fecal-orally via person-to-
person contact or ingestion of contaminated food or water (e.g., raw shellfish),
particularly in areas of poor sanitation. While the infection is rare in children (i.e.,
secondary to immunization), infected patients, such as
this incompletely immunized child, may experience varying degrees of severity.
Routine childhood vaccination schedules recommend children receive the first dose
of the hepatitis A vaccine at 12–23 months old, followed by a second dose at least 6
months later. The child's parents' decision to discontinue healthcare follow-up when
he turned six months old suggests he is unvaccinated against the HAV.
Clinical manifestations typically develop after a 2-6 week incubation period,
beginning with the abrupt onset of the prodromal phase,
including nausea, vomiting, anorexia, fever, malaise, and abdominal pain (i.e.,
right upper quadrant with tender hepatomegaly). Hepatic aminotransferases are
often elevated during the prodromal period and continue to rise early in the disease
process to > 1000 U/L. Within approximately two weeks, patients typically develop
bilirubinuria (e.g., dark urine) and pale stools, followed by jaundice and
pruritus. Prior to the onset of jaundice, prodromal symptoms typically abate.
Symptomatic HAV hepatitis is generally self-limited, with the goal of therapy being
supportive (e.g., fluids, antiemetics as needed). Immunization can reduce infection
risk and is recommended for all children 12 months or older, travelers to endemic
regions, and those with chronic liver disease.
[Choice B]: Hepatitis B virus (HBV) is a DNA hepadnavirus transmitted sexually,
parenterally (e.g., intravenous drug use, blood transfusions), or perinatally. The
incubation period ranges from 1-6 months, and it initially manifests as fever,
arthralgias, and rash; the course may eventually progress to malignancy. HBV
infection is unlikely in individuals with up-to-date vaccinations without these risk
factors. Since this child received all recommended vaccinations during his first six
months of life, it is implied that he is protected against HBV since the vaccine is
typically given in a three-shot series that begins at birth, 1-2 months, and 6-18
months of age.
[Choice C]: Gilbert syndrome is a benign genetic disorder characterized by mild
unconjugated hyperbilirubinemia due to relative UDP-glucuronosyltransferase
deficiency. Individuals with Gilbert syndrome are generally asymptomatic but may
occasionally experience transient episodes of jaundice in response to stress, fasting,
or illness. This patient's acute presentation and additional symptoms are
inconsistent with Gilbert syndrome.
[Choice D]: When biliary stones cause an obstruction within the common bile duct,
it is known as choledocholithiasis. Symptoms include right upper quadrant pain,
nausea, vomiting, and anorexia. Clinical features of extrahepatic cholestasis (e.g.,
jaundice, pale stools, dark urine) secondary to impaired bile flow may be present.
While these symptoms may be confused with those of acute viral hepatitis,
gallstone disease is exceedingly rare in otherwise healthy children. Also, this
patient's travel history and lack of appropriate protective immunization make
hepatitis A infection much more likely.
[Choice G]: Infection with the Chinese liver fluke (i.e., Clonorchis sinensis) can lead
to symptoms such as abdominal pain, jaundice, fatigue, and weight loss due to
chronic inflammation and obstruction of the bile ducts. Most cases occur in regions
of Asia where the consumption of raw freshwater fish is a common culinary practice.
Mexico is not an endemic region for liver fluke infections, so this patient's recent
travel is unlikely to have exposed him to this organism.
[Choice F]: Traveler's diarrhea is caused by enterotoxigenic Escherichia coli (ETEC)
and is typically characterized by the sudden onset of symptoms such as watery
diarrhea, abdominal cramps, nausea, and fever after travel to regions with poor
sanitation or inadequate hygiene practices. Most cases are self-limited and resolve
on their own with fluid replacement only. Hepatobiliary involvement and elevated
transaminases are not expected findings.
[Choice G]: Hepatitis D virus (HDV) infection may occur as a co-infection with HBV
or as a superinfection in chronic HBV carriers. Symptoms are similar to HBV, and the
prognosis is typically poor. Given this patient's lack of risk factors for HBV infection
and the absence of prolonged symptoms, HDV infection is unlikely.
Key Takeaway:
Hepatitis A virus (HAV) is a single-stranded RNA picornavirus that is
transmitted fecal-orally via person-to-person contact or contaminated food
and water sources. In young children, HAV infection is most commonly
asymptomatic but may also manifest as an acute, self-limited illness 2-4
weeks following exposure.
Symptoms include right upper quadrant pain, malaise, fatigue, anorexia,
nausea, vomiting, jaundice, and significant elevations in serum
aminotransferases.
