An outbreak of watery diarrhoea affects villagers who consumed water from a common well. Stool cultures grow Vibrio cholerae O1 biotype El Tor, serotype Ogawa. The MOST critical public health intervention to interrupt transmission at the population level is:

• A Mass antibiotic prophylaxis with doxycycline for all village residents
• B Isolation of all confirmed cases in a designated cholera treatment facility
• C Boiling/chlorination of water supply and oral cholera vaccine (OCV) for the affected community ✓
• D Ring vaccination of contacts of confirmed cases with OCV only

Explanation

Cholera control requires simultaneously addressing the source (water/sanitation) and boosting herd immunity. WHO recommends use of oral cholera vaccine (Shanchol or mORCVAX) as a complement — not substitute — to safe water and sanitation in outbreak settings. Boiling/hyperchlorination of the contaminated well is essential to eliminate the source. Mass antibiotic prophylaxis is not recommended (risk of resistance, logistical difficulty); antibiotics are only for confirmed cases. Isolation has limited impact for an environmentally transmitted disease.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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