El Tor biotype of Vibrio cholerae O1 has largely replaced Classical biotype worldwide. Compared to Classical, El Tor is characterised by which combination of features?
- A Milder clinical disease, longer environmental survival, Voges-Proskauer (VP) positive, haemolysin positive ✓
- B More severe clinical disease, shorter carrier state, VP negative
- C Higher case-fatality rate, shorter environmental persistence, haemolysin negative
- D Same clinical severity, identical environmental persistence, distinguished only by phage pattern
Correct answer: A. Milder clinical disease, longer environmental survival, Voges-Proskauer (VP) positive, haemolysin positive
Explanation
El Tor biotype compared to Classical biotype: produces milder (often asymptomatic) illness — ratio of inapparent to clinical infection is 25–100:1 vs 4:1 for Classical; survives longer in environment and water; Voges-Proskauer (VP) positive (produces acetoin); produces a haemolysin (El Tor haemolysin); more efficient at establishing a carrier state. The classical biotype is now predominantly restricted to Bangladesh/India historically. These features underpin El Tor's global dominance and persistent seventh pandemic.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.