Diarrhoea can be an early sign of any septic illness. In infants, stools may be so watery they are mistaken for urine.
It is important to note that breastfed babies often have loose stools, which is a normal physiological variation.
Gastroenteritis is a leading global cause of childhood morbidity and mortality, with ~1.5 million child deaths annually, largely due to dehydration.

Causes of Gastroenteritis

Viral causes:
- Rotavirus – most common in infants/children; accounts for ~600,000 childhood deaths annually (vaccine-preventable).
- Norovirus – common in adults and school-age children, outbreaks in communities.
- Astrovirus, Adenovirus, Human Metapneumovirus – less common but important causes.
Bacterial causes:
- Pneumococcus / Salmonella / E. coli / Shigella / Campylobacter – can cause severe or dysenteric diarrhoea.
- Vibrio cholerae – causes massive watery diarrhoea in endemic regions.
Parasitic causes: Giardia, Cryptosporidium, Entamoeba histolytica (persistent or recurrent diarrhoea).

⚠️ Worsening Clinical Features of Dehydration

Feature	Mild / None	Moderate	Severe
General appearance	Alert, normal	Thirsty, restless, irritable	Drowsy, floppy, cold peripheries
Eyes	Normal	Slightly sunken	Very sunken
Mucous membranes	Moist	Sticky	Dry
Tears	Present	Decreased	Absent
Skin turgor	Normal	Slow recoil	Very slow / >2 sec
Urine output	Normal	Reduced	Minimal / absent

🔎 Investigations

Usually clinical diagnosis in the UK.
Stool microscopy and culture if:
- Blood or mucus in stool
- History of recent foreign travel
- Immunocompromised child
- Outbreak suspected
Blood tests: U&E, glucose if severe dehydration or IV fluids are required.

⚠️ Complications

Dehydration → most dangerous, may progress to hypovolaemic shock.
Malnutrition → due to prolonged illness and reduced intake.
Temporary lactose intolerance → watery acidic stools post-illness; resolves with lactose-free diet in 1–2 weeks.
Post-enteritis enteropathy → persistent gut dysfunction, usually resolves spontaneously over ~7 weeks.

💊 Management

Oral Rehydration Therapy (ORT):
- Gold standard: Dioralyte® 50 mL/kg over 4 hours (≈1 mL/kg every 5 min).
- Continue breastfeeding.
- If refusing ORT → try small sips, spoon feeding, NG tube if needed.
IV fluids: Only for severe dehydration, shock, or failed ORT (use 0.9% NaCl + 5% glucose).
Antiemetics: Ondansetron (0.1–0.15 mg/kg) may reduce vomiting and admissions; not yet universal in NICE guidance.
Avoid: Fruit juices, fizzy drinks, antidiarrhoeal drugs (e.g., loperamide contraindicated in children).

Prevention

Rotavirus vaccination (part of UK immunisation schedule).
Hand hygiene, safe food prep, clean water.
Education for parents on red flags (persistent vomiting, blood in stool, lethargy).

Conclusion

Gastroenteritis is usually self-limiting but dangerous due to risk of dehydration.
ORT is cornerstone of management; IV fluids reserved for severe/shock.
Vaccination, hygiene, and parental education remain key to prevention.

References

NICE CG84: Diarrhoea and vomiting caused by gastroenteritis in under 5s.
WHO: Management of Childhood Illness – Diarrhoea Guidelines.
BMJ Best Practice: Acute gastroenteritis in children.

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Gastroenteritis in Children

Introduction