Dermatology MCQ - Viral Infections - Hepatitis A infection

A 25-year-old college student presents with a 3-day history of fever, malaise, nausea, and dark urine. On examination, you note scleral icterus and tender hepatomegaly. Laboratory studies show elevated ALT (1200 U/L), AST (1000 U/L), total bilirubin 5.2 mg/dL, and positive anti-hepatitis A virus (HAV) IgM. The patient reports recently eating raw oysters at a seafood restaurant. Which of the following is the primary mode of transmission for this infection?

A) Fecal-oral route
B) Percutaneous exposure
C) Sexual contact
D) Respiratory droplets
E) Vertical transmission

Correct Answer: A) Fecal-oral route

Explanation

This presentation is classic for acute hepatitis A virus (HAV) infection, characterized by jaundice, hepatomegaly, and markedly elevated transaminases.

Key Clinical Features of Hepatitis A:

• Prodromal Phase: Fever, malaise, anorexia, nausea, vomiting, and abdominal pain.

• Icteric Phase: Jaundice, scleral icterus, dark urine (bilirubinuria), and pale stools.

• Hepatomegaly: Tender liver enlargement.

• Laboratory Findings:

  • Elevated ALT and AST (often >1000 U/L).

  • Elevated total bilirubin (direct and indirect).

  • Positive anti-HAV IgM (diagnostic for acute infection).

• Epidemiology: Linked to consumption of contaminated food (e.g., raw shellfish, salads) or water, or close contact with an infected person.

Mode of Transmission:

• Fecal-oral route is the primary mode.

  • Virus is shed in feces during the incubation and early acute phases.

  • Transmission occurs through:

    • Ingestion of contaminated food or water (e.g., raw oysters, unwashed produce).

    • Close person-to-person contact (e.g., household, daycare centers).

    • Poor hand hygiene after defecation.

• Not transmitted via blood, sexual contact (unless oral-anal), or respiratory droplets.

Why Not the Other Options?

• (B) Percutaneous exposure: Typical for hepatitis B and C (e.g., needlestick injuries, IV drug use).

• (C) Sexual contact: Typical for hepatitis B and HIV; rare for HAV (only if oral-anal contact).

• (D) Respiratory droplets: Typical for influenza or measles; not for HAV.

• (E) Vertical transmission: Typical for hepatitis B, HIV, or syphilis; not for HAV.

Management:

• Supportive care: Rest, hydration, avoid hepatotoxic substances (e.g., alcohol, acetaminophen).

• Post-exposure prophylaxis: Administer HAV vaccine or immune globulin to close contacts.

• Prevention: Vaccination (recommended for travelers, men who have sex with men, IV drug users), and good hand hygiene.

Prognosis:
Typically self-limiting; no chronic infection. Fulminant hepatitis is rare (<1%).

Note: The history of consuming raw oysters is a classic clue for HAV, as filter-feeding shellfish can concentrate the virus from contaminated water. Always consider HAV in acute hepatitis with fecal-oral exposure risk.