Hepatitis E virus (HEV): What is the principal route of human-to-human transmission in community outbreaks?

Introduction / Context:
Hepatitis E virus (HEV) is a non-enveloped, single-stranded RNA virus that commonly causes acute viral hepatitis in regions with limited sanitation. Exam questions often test recognition of its classic faecal–oral transmission, especially via contaminated municipal water during monsoon or flood-related disruptions.

Given Data / Assumptions:

• Disease focus: Hepatitis E (classically epidemic waterborne hepatitis).
• Population setting: community outbreaks, particularly in areas with compromised water and sewage systems.
• We seek the most common and epidemiologically dominant transmission route.

Concept / Approach:
Unlike hepatitis B and C (bloodborne and parenteral), HEV spreads primarily via the faecal–oral route. Large outbreaks follow ingestion of water contaminated with human sewage. Sporadic zoonotic genotypes exist, but the exam emphasis remains on waterborne spread in endemic regions.

Step-by-Step Solution:
Identify hallmark: faecal–oral transmission dominates HEV epidemiology. Link to outbreaks: community water contamination causes explosive epidemics. Contrast with other options: parenteral and sexual routes are not typical for HEV outbreaks. Select the best match: faecally contaminated drinking water.

Verification / Alternative check:
Public health reports repeatedly implicate contaminated piped water or wells in HEV outbreaks; case control studies show strong association with unsafe drinking water and inadequate sanitation.

Why Other Options Are Wrong:
Infected syringes/needles: characteristic of HBV/HCV, not the main HEV route. Sexual intercourse: not a dominant HEV pathway. “None of these” and shellfish-only are too restrictive and miss the classic waterborne pattern.

Common Pitfalls:
Confusing HEV with HAV or HBV; assuming all hepatitis viruses share the same transmission route. HEV is best remembered as “epidemic waterborne hepatitis.”

Final Answer:
Faecally contaminated drinking water.