Pathophysiology
Curved Gram-negative rod, non-invasive, colonises small bowel; cholera toxin (A/B subunit) ADP-ribosylates Gs alpha -> constitutive adenylyl cyclase -> cAMP-driven Cl-/HCO3-/water secretion -> massive isotonic fluid loss.
Sources: WHO Cholera Fact Sheet (2024); WHO Global Task Force on Cholera Control (Roadmap 2030); CDC Cholera Guidelines
Clinical presentation
Sudden painless watery 'rice-water' diarrhoea with fishy odour, projectile vomiting, muscle cramps, sunken eyes, poor skin turgor. Hypovolaemic shock and death within hours if untreated; metabolic acidosis and hypokalaemia.
Diagnosis
Clinical in outbreaks; confirm with stool culture on TCBS agar or dark-field microscopy showing 'shooting-star' motility. Rapid dipstick antigen tests for surveillance.
Management
Aggressive rehydration is life-saving. Mild/moderate: WHO ORS with reduced osmolarity. Severe (>=10% loss, shock): rapid IV Ringer's lactate 100 mL/kg over 3-6 h. Add zinc for children. Doxycycline 300 mg single dose (or azithromycin) shortens duration and volume of diarrhoea in moderate/severe cases.
Prevention
Safe water, sanitation, hygiene (WASH). Oral cholera vaccines (Dukoral, Shanchol, Euvichol) for outbreak response and endemic areas.
