Cholera
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Cholera is an acute diarrhoeal illness caused by Vibrio cholerae, leading to rapid dehydration and electrolyte imbalances due to profuse watery diarrhoea.
Aetiology
- Caused by toxin-producing Vibrio cholerae serogroups O1 and O139.
- Transmitted via ingestion of contaminated water or food.
- Associated with poor sanitation and overcrowding.
Pathophysiology
- Cholera toxin activates adenylate cyclase in intestinal epithelial cells.
- Increased cyclic AMP (cAMP) levels lead to chloride and water secretion.
- Results in profuse watery diarrhoea, dehydration, and electrolyte loss.
Risk Factors
- Consumption of untreated water or contaminated food.
- Poor sanitation and inadequate sewage disposal.
- Malnutrition and immunosuppression.
- Travel to or residence in endemic areas.
Signs and Symptoms
- Profuse, watery diarrhoea ("rice water stools").
- Severe dehydration (sunken eyes, dry mucous membranes, hypotension).
- Muscle cramps due to electrolyte imbalance.
- Hypovolaemic shock in severe cases.
Investigations
- Stool culture: confirms V. cholerae and guides antibiotic therapy.
- Stool PCR: detects cholera toxin genes.
- Rapid antigen tests: for field diagnosis in outbreaks.
- Serum electrolytes and renal function: assess for dehydration and acidosis.
Management
1. Fluid Resuscitation:
- Oral rehydration solution (ORS) for mild to moderate dehydration.
- IV fluids for severe dehydration.
2. Antibiotic Therapy:
- First line: azithromycin or doxycycline.
- Alternative: ciprofloxacin in resistant cases.
- Antibiotics shorten disease duration and reduce transmission.
3. Nutritional Support:
- Encourage continued feeding, particularly in children.
- Zinc supplementation to reduce diarrhoea severity.
4. Prevention:
- Safe drinking water and improved sanitation.
- Oral cholera vaccine for high risk populations.
- Public health measures in outbreak settings.
5. Referral:
- Infectious diseases: for severe cases or outbreaks.
- Intensive care: for patients with severe dehydration and shock.
- Public health: for outbreak management and surveillance.