A 35-year-old man from rural India presents with jaundice, dark urine, and abdominal pain for 2 weeks. Serum ALT is 2800 IU/L, total bilirubin 8.2 mg/dL, and INR 1.8. Anti-HAV IgM is positive. What is the most common mode of transmission of the causative agent in this patient?

Explanation

## Hepatitis A Epidemiology and Transmission **Key Point:** Hepatitis A virus (HAV) is transmitted exclusively via the fecal-oral route, typically through contaminated water or food in endemic regions like India. ### Transmission Routes of Viral Hepatitis | Virus | Primary Route | Secondary Route | Vertical Transmission | |-------|---------------|-----------------|----------------------| | HAV | Fecal-oral | None significant | No | | HBV | Percutaneous/sexual | Vertical (high risk) | Yes (90% if HBeAg+) | | HCV | Percutaneous | Sexual (rare) | Yes (5–10%) | | HDV | Percutaneous/sexual | Vertical (rare) | Rare | | HEV | Fecal-oral | Percutaneous (rare) | Yes (high risk in 3rd trimester) | **High-Yield:** HAV is a non-enveloped RNA virus; it survives gastric acid and bile, allowing infection via the GI tract. It does NOT integrate into the genome and does NOT cause chronic infection. **Clinical Pearl:** In rural India, HAV is endemic with seroprevalence >90% by age 10. Acute infection presents with marked transaminitis (ALT often >1000 IU/L), but fulminant hepatic failure is rare (<0.1%) except in patients with underlying cirrhosis. **Mnemonic — HAV Characteristics:** **SAFE** — **S**ecure (non-enveloped, resistant), **A**cute only (no chronic), **F**ecal-oral, **E**xcellent prognosis. ### Why Fecal-Oral Is Correct The patient's presentation (acute hepatitis with positive anti-HAV IgM in an endemic rural area) is classic for HAV. Contaminated water sources are the primary epidemiological link in developing countries. HAV replicates in the intestinal epithelium and is shed in stool weeks before jaundice appears, making fecal-oral transmission the dominant mechanism.