Acute Gastroenteritis in Children

Acute gastroenteritis in children is sudden onset of loose or watery stools, with or without vomiting and fever, lasting under 14 days, and it is a leading cause of dehydration and death in children under 5 years in low-income settings.

• Rotavirus is the commonest cause of severe disease where vaccine is not used. Norovirus, adenovirus, astrovirus and sapovirus are other viral causes.
• Bacterial causes include Escherichia coli (enterotoxigenic, enteropathogenic), Shigella, Campylobacter, non-typhoidal Salmonella and Vibrio cholerae. Protozoa include Cryptosporidium, Giardia and Entamoeba histolytica.
• Spread is faeco-oral through contaminated water, food and hands.
• Risk factors include malnutrition, HIV, lack of breastfeeding, poor sanitation, unsafe water, measles and age under 2 years.
• Death results from dehydration, electrolyte disturbance and sepsis.

Assessment of dehydration drives management.

• Diarrhoea (three or more loose stools in 24 hours), vomiting, low-grade fever and abdominal pain.
• No dehydration: alert, normal thirst, normal skin pinch, normal eyes.
• Some dehydration: restless or irritable, sunken eyes, drinks eagerly, skin pinch goes back slowly.
• Severe dehydration: lethargic or unconscious, sunken eyes, unable to drink or drinks poorly, skin pinch goes back very slowly (over 2 seconds).
• Dysentery: blood in stool, suggesting Shigella, Campylobacter, Entamoeba histolytica or enterohaemorrhagic Escherichia coli.
• Persistent diarrhoea (14 days or more) suggests malnutrition, HIV, lactose intolerance or persistent infection.
• Differential diagnosis: sepsis, urinary tract infection, otitis media, pneumonia, meningitis, appendicitis, intussusception, malaria, diabetic ketoacidosis, food allergy and inflammatory bowel disease.
• Complications: dehydration, hypovolaemic shock, hypernatraemia, hyponatraemia, hypokalaemia, metabolic acidosis, acute kidney injury, haemolytic uraemic syndrome, ileus, persistent diarrhoea, malnutrition, and bacteraemia.

Diagnosis is clinical, with investigation of selected children.

• Assess hydration, weight, mental state, capillary refill, and look for features of shock.
• Stool microscopy and culture for bloody diarrhoea, suspected cholera, immunocompromise, severe or persistent disease.
• Stool polymerase chain reaction panels where available.
• Blood glucose in lethargic children. Electrolytes, urea and creatinine in severe dehydration, shock or prolonged course.
• Blood culture if toxic or febrile.
• Full blood count, urea and creatinine, and film if haemolytic uraemic syndrome is suspected (anaemia, thrombocytopenia, renal failure).

Rehydration with oral rehydration solution and zinc is the core of treatment.

• No dehydration: continue breastfeeding and usual feeds. Give extra fluids: oral rehydration solution 50 to 100 mL after each loose stool for under 2 years, 100 to 200 mL for ages 2 to 10 years, and as much as wanted for older children.
• Some dehydration: low-osmolarity oral rehydration solution 75 mL/kg over 4 hours, reassess, and then give extra fluids after each loose stool (50 to 100 mL under 2 years, 100 to 200 mL from 2 to 10 years) with continued feeds. Give small frequent sips (5 mL every 1 to 2 minutes), continuing if the child vomits after waiting 10 minutes.
• Severe dehydration or shock: intravenous Ringer's lactate or normal saline 100 mL/kg, given as 30 mL/kg over 30 minutes (infants under 12 months: over 1 hour) then 70 mL/kg over 2.5 hours (5 hours for infants). In shock, give 20 mL/kg boluses. Reassess every 15 to 30 minutes. Switch to oral rehydration solution as soon as the child can drink. Nasogastric oral rehydration solution at 20 mL/kg/h for 6 hours if intravenous access fails.
• Zinc: 10 mg daily for 10 to 14 days for under 6 months, 20 mg daily for 6 months and above.
• Continue feeding during and after rehydration. Give an extra meal daily for 2 weeks after recovery.
• Antibiotics are given only for dysentery (ciprofloxacin 15 mg/kg twice daily for 3 days, or azithromycin 10 mg/kg once daily for 3 days), suspected cholera with severe dehydration (azithromycin 20 mg/kg single dose, or doxycycline 4 mg/kg single dose for ages 8 years and above), or confirmed Giardia or Entamoeba infection (metronidazole 10 mg/kg three times daily for 5 to 7 days).
• Antiemetics: ondansetron 0.15 mg/kg single dose (maximum 8 mg) may help oral rehydration in children with vomiting aged 6 months and above. Antimotility drugs, antispasmodics and adsorbents are not used.
• Prevention: rotavirus vaccine, exclusive breastfeeding for 6 months, handwashing, safe water and sanitation, measles immunisation, and vitamin A supplementation.
• Special groups: malnourished children need reduced-osmolarity rehydration solution for malnutrition (ReSoMal) 5 mL/kg every 30 minutes for the first 2 hours, and careful fluid volumes. Infants under 2 months and children with HIV need admission.
• Red flags: severe dehydration, shock, lethargy, bloody stool with fever, persistent vomiting, bilious vomiting, abdominal distension, seizure, oliguria and age under 3 months.
• Follow-up: review in 2 days, or earlier if not improving. Return if drinking poorly, blood in stool, repeated vomiting or fever.