Cholera outbreak control — DTM&H MCQ

Correct answer: D — Rapid rehydration services with safe water and chlorination

The correct answer is D, rapid rehydration services with safe water and chlorination. Profuse watery diarrhoea with rice-water stools and rapid onset of severe dehydration after a flood affecting sanitation is the classic presentation of cholera, and case fatality is driven almost entirely by dehydration rather than the infection itself. The most important public health measure is therefore aggressive oral and intravenous rehydration combined with restoring safe water supplies and chlorination to interrupt the faecal-oral transmission route from contaminated water. This dual approach (treat the dehydration, fix the water) addresses both immediate mortality and ongoing spread in an outbreak setting where latrines have failed and water sources are likely contaminated. Prompt rehydration can reduce cholera mortality from over 20 percent to under 1 percent, making it the single highest-yield intervention. Why the other options are wrong: E. Routine stool microscopy before rehydration: Diagnostic confirmation must never delay treatment in a clinically obvious outbreak; rehydration is started on clinical grounds while samples are sent for confirmation, not before. C. Mass doxycycline for the entire district: Antibiotics are reserved for severely dehydrated cases to shorten duration and reduce transmission, not given as mass chemoprophylaxis across a district, which risks resistance and is not the priority intervention. A. BCG vaccination campaign: BCG protects against tuberculosis and has no role in cholera prevention or outbreak control. B. Household isolation for 6 weeks: Cholera spreads via contaminated water and food, not close contact, so prolonged isolation is ineffective and diverts resources from water, sanitation and rehydration efforts. Key point: In a cholera outbreak, rapid rehydration together with safe water and sanitation measures is the single most effective intervention to cut mortality and transmission.

Reference: NaTHNaC (travelhealthpro.org.uk), Cholera clinical guidance, 2024, https://travelhealthpro.org.uk/disease/32/cholera