Cholera Epidemics: Transmission, Clinical Features & Public Health Response

Cholera = acute watery diarrhea from Vibrio cholerae O1/O139 toxin. Epidemics occur where sanitation fails.

Transmission

• Fecal-oral: contaminated water (primary), food (seafood, raw vegetables), fomites.
• Incubation: 2 hrs – 5 days (usually 2–3 days).
• Asymptomatic carriers shed 10³–10⁷ CFU/mL for weeks.

Clinical Presentation

• Rice-water stools: Profuse, painless, watery, flecks of mucus.
• Vomiting: Early, projectile.
• Dehydration: Rapid (1 L/hr possible) → sunken eyes, poor skin turgor, oliguria, shock.
• Electrolytes: Hypokalemia, hypocalcemia, metabolic acidosis.

Treatment (WHO)

1. Rehydration: ORS (75 mEq/L Na⁺) for mild/mod; IV RL/NS for severe (100 mL/kg first 3 hrs).
2. Antibiotics: Doxycycline 300 mg single dose (adults); azithromycin (kids/pregnant). Reduces volume/duration 50%.
3. Zinc: 20 mg/day × 10 days (children).

Epidemic Control

• Water: Chlorination (0.2–0.5 mg/L free Cl₂), safe storage.
• Sanitation: Latrines, waste management.
• Hygiene: Handwashing, food safety.
• Vaccination: Oral killed whole-cell (Shanchol, Euvichol) — 2 doses, 65% efficacy × 3–5 yrs. Reactive campaigns in outbreaks.
• Surveillance: Rapid tests, line lists, mapping.

Global Burden

1.3–4M cases, 21,000–143,000 deaths/year (WHO). Endemic in 47 countries. Climate change, conflict, displacement drive resurgence.