Acute Gastroenteritis (Diarrhea) in Children: Case Discussion and Key Points
Model Case Presentation
Patient Demographics
Name: Master Arjun, Age: 14 months, Gender: Male, Informant: Mother (Reliable)
Chief Complaints
- Loose, watery stools — 3 days (8–10 episodes/day)
- Vomiting — 3 days (4–5 episodes/day)
- Fever — 2 days
History Summary
Sudden onset of large-volume, watery, non-bloody stools 3 days ago. Each stool is large in amount, without mucus or blood. Vomiting started simultaneously — bilious, non-projectile. Fever is low-grade. No contact with similar illness at home. No recent travel. On weaning diet; no history of antibiotic use. Child is irritable, crying with reduced tears, not passing urine for the last 6 hours. Urine output before illness was 6–8 times a day. Mother notices sunken eyes and dry mouth for 1 day. Breastfed till 10 months; currently on complementary feeds. Immunized up to date including Rotavirus vaccine (2 and 4 months).
No blood or mucus in stools (against bacterial dysentery). No similar illness in family. Antenatal and birth history uneventful. No known drug allergies.
Examination Summary
| Parameter | Finding | Significance |
|---|---|---|
| Weight (current) | 9.2 kg | Down from 10 kg (8% weight loss — moderate dehydration) |
| Temperature | 38.4°C | Low-grade fever — viral etiology likely |
| HR | 132/min | Tachycardia (dehydration) |
| RR | 38/min | Tachypnea (acidosis/fever) |
| BP | 88/60 mmHg | Low normal (compensated) |
| CRT | 3 seconds | Prolonged (moderate dehydration) |
| Anterior fontanelle | Sunken | Dehydration |
| Eyes | Sunken, reduced tears | Dehydration |
| Oral mucosa | Dry | Dehydration |
| Skin turgor | Reduced (pinch recoil 1–2 seconds) | Moderate dehydration |
| Abdomen | Soft, mild diffuse tenderness, active bowel sounds | Enteritis |
| CNS | Irritable but consolable | Moderate dehydration |
✅ Complete Diagnosis
Acute Watery Diarrhea (Viral Gastroenteritis — likely Rotavirus) with Moderate Dehydration (estimated 8% body weight) and Metabolic Acidosis.
📝 History — Exam Q&A
Acute Gastroenteritis (AGE): Inflammation of the gastrointestinal tract characterized by diarrhea with or without nausea, vomiting, fever, or abdominal pain, with rapid onset and duration less than 14 days.
Diarrhea (WHO definition): Passage of 3 or more loose/watery stools per day, or more frequent passage than what is normal for that individual, within a 24-hour period.
Acute diarrhea: Duration < 14 days. Persistent diarrhea: 14–30 days. Chronic diarrhea: > 30 days.
| Category | Organisms | Stool Character |
|---|---|---|
| Viral (most common) | Rotavirus (#1 worldwide), Norovirus, Adenovirus (40/41), Astrovirus | Watery, large volume, no blood/mucus |
| Bacterial | ETEC, Salmonella, Shigella, Campylobacter, Vibrio cholerae, EPEC | Varies — watery to bloody/mucoid |
| Parasitic | Giardia lamblia, Cryptosporidium, Entamoeba histolytica | Watery, fatty, or bloody |
💡 Mnemonics
Most common viral cause: Rotavirus (worldwide in unvaccinated); Norovirus (#1 in vaccinated populations and outbreaks in older children/adults).
Most common bacterial cause in developing countries: ETEC (Enterotoxigenic E. coli).
About the diarrhea:
- Onset and duration?
- Frequency — number of stools per day?
- Volume — small or large volume per stool?
- Consistency — watery, loose, semi-solid?
- Color — yellow/green/rice water?
- Any blood or mucus? (suggests dysentery/invasive bacteria)
- Any foul smell? (malabsorption)
Associated symptoms: Vomiting (onset, frequency, character), fever, abdominal pain/cramps, tenesmus
Hydration status: Urine output (last void?), oral intake, tears, activity level
Epidemiology: Similar illness in family/contacts, food intake history, water source, travel history
Past history: Similar episodes before, malnutrition, immunodeficiency, antibiotic use (C. diff)
Immunization: Rotavirus vaccine status
| Feature | Acute Watery Diarrhea | Dysentery |
|---|---|---|
| Blood in stool | Absent | Present (visible blood) |
| Mucus | Absent | Present |
| Stool volume | Large volume | Small volume, frequent |
| Tenesmus | Absent | Often present |
| Abdominal pain | Mild/cramps | Severe colicky pain |
| Fever | Low-grade or absent | High fever common |
| Common etiology | Rotavirus, ETEC, Cholera | Shigella, Campylobacter, Entamoeba |
| Antibiotic | Not needed (viral) | Required (bacterial) |
- Age: 6 months – 2 years (peak); rare below 3 months (maternal antibodies) and above 5 years (acquired immunity)
- Season: Winter months (cool, dry weather) — "winter vomiting diarrhea"
- Onset: Sudden; vomiting often precedes diarrhea
- Stool: Watery, large volume, yellow-green, NO blood/mucus
- Fever: Low-grade (38–39°C)
- Dehydration: Rapid and severe — leading cause of pediatric diarrhea deaths
- Duration: 5–7 days (self-limited)
- Extraintestinal: Occasionally causes febrile seizures (rare), hepatitis (rare)
- Signs of severe dehydration or shock (sunken eyes, cold extremities, absent pulses, unconscious)
- Altered consciousness / lethargy / convulsions
- Unable to drink or breastfeed
- Persistent vomiting (unable to retain oral fluids)
- Blood in stool (dysentery)
- High fever (>39°C in infant)
- Abdominal distension or rigidity (surgical emergency?)
- Underlying malnutrition or immunodeficiency
- Age < 2 months
- Failed home ORS trial
- Surgical: Intussusception (currant jelly stools, colicky pain, sausage mass), Appendicitis, Intestinal obstruction
- Medical: Urinary tract infection (fever + diarrhea in infants), Hemolytic Uremic Syndrome (post-E.coli O157:H7 — bloody diarrhea + AKI + hemolysis), Inflammatory bowel disease, Celiac disease, Cow's milk protein allergy
- Metabolic: Diabetic ketoacidosis, Adrenal insufficiency
- Toxins: Food poisoning (Staph aureus, Bacillus cereus — rapid onset vomiting within 1–6 hours)
- Antibiotic-associated: Clostridioides difficile colitis
| Type | Mechanism | Features | Example |
|---|---|---|---|
| Secretory | Active secretion of electrolytes/water into gut lumen; inhibition of absorption | Large volume, watery; persists with fasting; osmotic gap <50 | Cholera (V. cholerae CT), ETEC, VIPoma |
| Osmotic | Non-absorbed solutes draw water into lumen by osmosis | Stops with fasting; osmotic gap >125 | Lactose intolerance, lactulose, Rotavirus (destroys villi) |
| Invasive/Inflammatory | Mucosal invasion → inflammation, ulceration → blood/mucus | Small volume, bloody mucoid stools, fever, tenesmus | Shigella, Campylobacter, Salmonella, Entamoeba |
| Motility | Altered intestinal motility | Variable | Hyperthyroidism, IBS |
💡 Rotavirus mechanism
Rotavirus destroys enterocytes at the tips of intestinal villi → reduced absorptive capacity (osmotic) + NSP4 protein acts as a viral enterotoxin → secretory component. It is thus both osmotic and secretory.
🩺 Examination — Exam Q&A
| Sign | No Dehydration | Some Dehydration | Severe Dehydration |
|---|---|---|---|
| % body weight lost | <5% | 5–10% | >10% |
| General condition | Well, alert | Restless, irritable | Lethargic/unconscious |
| Eyes | Normal | Sunken | Very sunken, dry |
| Tears | Present | Reduced | Absent |
| Mouth/tongue | Moist | Dry | Very dry |
| Thirst | Normal | Thirsty, drinks eagerly | Unable/drinks poorly |
| Skin turgor | Normal (<1 sec) | Slow (1–2 sec) | Very slow (>2 sec) |
| Fontanelle | Normal/flat | Sunken | Very sunken |
| CRT | <2 sec | 2–3 sec | >3 sec |
| Urine output | Normal | Reduced | Minimal/none |
| WHO Plan | Plan A | Plan B | Plan C |
The Goldman Clinical Dehydration Scale (CDS) is validated for children aged 1 month to 5 years. It scores 4 parameters (0–2 each), total score 0–8.
| Parameter | 0 | 1 | 2 |
|---|---|---|---|
| General appearance | Normal | Thirsty, restless, or lethargic | Limp, cold, drowsy/comatose |
| Eyes | Normal | Slightly sunken | Very sunken |
| Mucous membranes | Moist | Sticky | Dry |
| Tears | Tears present | Decreased | Absent |
Interpretation: Score 0 = no dehydration; 1–4 = mild–moderate; 5–8 = severe dehydration
No single sign is perfectly reliable; dehydration is a clinical constellation. However:
- Best combination: Prolonged skin turgor (>2 sec) + sunken eyes + altered general condition — when ≥3 signs are present, moderate-severe dehydration is almost certain
- Most specific single sign for severe dehydration: Prolonged skin pinch (>2 seconds)
- Most sensitive: Sunken eyes
- Best objective measure: Acute weight loss (pre-illness weight minus current weight)
💡 Important caveat
In hypernatremic dehydration, skin turgor may be NORMAL (doughy consistency) despite significant dehydration — because the increased interstitial sodium draws water into cells and maintains skin elasticity. This can lead to underestimation of dehydration.
- Cold, mottled extremities with prolonged CRT (>3 seconds)
- Weak or absent peripheral pulses
- Tachycardia out of proportion to fever
- Hypotension (late sign — shock already decompensated)
- Altered consciousness/unresponsiveness
- Reduced/absent urine output
- Rapid deep breathing (Kussmaul breathing) — metabolic acidosis
🚨 Key Point
BP is maintained until >25–30% blood volume is lost in children (compensatory tachycardia, vasoconstriction). Hypotension = late/decompensated shock. Do not wait for BP to fall before intervening.
| Type | Serum Na | Cause | Clinical features |
|---|---|---|---|
| Isonatremic (most common ~70%) | 130–150 mEq/L | Equal Na and water loss | Classic dehydration signs |
| Hyponatremic (~20%) | <130 mEq/L | Water excess or excessive hypotonic fluid replacement | Drowsiness, seizures, edema; signs appear at lower % dehydration |
| Hypernatremic (~10%) | >150 mEq/L | Water loss > Na loss (high solute feeds, fever, watery diarrhea) | Doughy skin, intense thirst, irritability, high-pitched cry, seizures; signs underestimate dehydration |
Assess weight-for-height, MUAC (mid-upper arm circumference), look for signs of SAM (severe acute malnutrition): edema, visible severe wasting, MUAC <11.5 cm.
Why it matters:
- Malnourished children have altered dehydration signs (falsely appear less dehydrated than they are)
- They are at higher risk of hypoglycemia, hypothermia, electrolyte imbalances
- Standard WHO ORS is NOT used in SAM with diarrhea — use ReSoMal (modified ORS for SAM) to avoid fluid overload and hyponatremia
- Higher mortality from AGE in malnourished children
- Hypovolemic shock — inadequate tissue perfusion
- Acute Kidney Injury — prerenal azotemia, oliguria
- Metabolic acidosis — HCO₃ loss in diarrheal stool, lactic acidosis from poor perfusion
- Hypokalemia — excessive K⁺ loss in stool (weakness, ileus, cardiac arrhythmia)
- Hypoglycemia — especially in malnourished infants with reduced glycogen stores
- Seizures — from hypernatremia, hyponatremia, hypoglycemia, or high fever
- DIC — in septic shock
- Aspiration pneumonia — from vomiting with decreased sensorium
- Hemolytic Uremic Syndrome — complication of STEC (Shiga toxin E. coli) — microangiopathic hemolytic anemia + thrombocytopenia + AKI
🔬 Investigations — Exam Q&A
No investigations needed in mild-moderate viral AGE managed in the outpatient setting. Most cases of AGE in children are self-limiting viral illnesses.
Investigations indicated in:
- Severe or moderate-severe dehydration (electrolytes, urea, creatinine, glucose, blood gas)
- Dysentery (bloody diarrhea) — stool microscopy and culture
- Suspected HUS (CBC, blood film, renal function)
- Prolonged diarrhea (>7 days)
- Immunocompromised host
- Hospitalized patients — blood glucose monitoring (risk of hypoglycemia)
- Suspected systemic infection / sepsis
| Feature | Viral (Secretory) | Bacterial Dysentery (Invasive) | Parasitic (Giardia) | Amoebiasis |
|---|---|---|---|---|
| Color | Yellow/green watery | Mucoid, bloody | Pale, greasy, foul-smelling | Blood + mucus ("anchovy sauce") |
| Blood/Mucus | Absent | Present | Absent | Blood + mucus (+ Charcot–Leyden crystals) |
| Microscopy (WBC) | No WBC/RBC | WBC >5/HPF, RBC present | Cysts/trophozoites | Flask-shaped trophozoites with RBC (E. histolytica) |
| Culture | Negative (viral) | Positive (Shigella, Salmonella, etc.) | Not needed | Not needed |
| Investigation | Expected Finding | Significance |
|---|---|---|
| Serum Sodium | Variable (iso/hypo/hypernatremia) | Type of dehydration; guides fluid management |
| Serum Potassium | Usually low (Hypokalemia) | Excessive loss in diarrheal stool; masked by acidosis |
| Serum Bicarbonate/CO₂ | Low (<18 mEq/L) | Metabolic acidosis (HCO₃ loss + lactic acidosis) |
| Urea/Creatinine | Elevated (pre-renal AKI) | Severity of dehydration |
| Blood Glucose | Low or low-normal | Hypoglycemia risk (especially infants) |
| CBC | Hemoconcentration (↑PCV/Hb); ↑WBC if bacterial | Dehydration severity; etiology |
| Blood pH / Base excess | Low pH, ↑ base deficit | Degree of metabolic acidosis |
- Rotavirus rapid antigen test (ELISA-based) on stool: Sensitivity ~90–95%, Specificity ~99%. Used for epidemiological confirmation, not routine clinical practice.
- Gold standard: Electron microscopy of stool (shows characteristic wheel-like appearance of rotavirus). Rarely used clinically — only in research or outbreak investigation.
- RT-PCR: Most sensitive and specific; used in reference labs for genotyping (G and P types).
- Stool culture: Used for bacterial AGE — sensitivity ~50-80% depending on organism and timing.
HUS triad: Microangiopathic hemolytic anemia + Thrombocytopenia + Acute Kidney Injury (oliguria)
Clue in history: Bloody diarrhea 5–10 days before HUS develops (post-STEC infection, especially E. coli O157:H7)
Blood investigations in HUS:
- Anemia (Hb sharply falling) with fragmented RBCs (schistocytes) on peripheral smear
- Thrombocytopenia (<150,000/μL)
- Elevated urea, creatinine (AKI)
- Elevated LDH, low haptoglobin (hemolysis markers)
- Negative Coombs test (microangiopathic — not immune hemolysis)
- Stool culture — STEC (E. coli O157:H7) or Shiga toxin PCR
🚨 Important
Avoid antibiotics in STEC infection — they may increase Shiga toxin release and worsen HUS. Avoid antiperistaltic agents (loperamide) for same reason.
💊 Management — Exam Q&A
| Plan | Dehydration | Setting | Treatment |
|---|---|---|---|
| Plan A | No dehydration | Home |
Continue feeding + ORS after each loose stool: — <2 yr: 50–100 mL ORS per stool — >2 yr: 100–200 mL ORS per stool + Zinc supplementation (10–20 mg/day × 14 days) |
| Plan B | Some dehydration | Health facility (ORS corner) |
ORS 75 mL/kg over 4 hours Reassess every hour If vomiting: give small sips; wait 10 min then resume After 4 hr: reassess → move to Plan A or C |
| Plan C | Severe dehydration / Shock | Hospital + IV access |
IV Ringer's Lactate (preferred) or Normal Saline: — 100 mL/kg over 3 hr (infant) or 2–3 hr (older child) — First 30 mL/kg in 1 hr if shock Monitor response; shift to ORS as soon as tolerated |
ORS works by the principle of sodium-glucose cotransport (SGLT-1) — glucose absorption in the intestine drives sodium absorption even when secretory mechanisms are active (e.g., in cholera/viral enteritis).
| Component | Standard ORS (pre-2002) | Low Osmolarity ORS (WHO 2002) |
|---|---|---|
| Sodium | 90 mmol/L | 75 mmol/L |
| Glucose | 111 mmol/L | 75 mmol/L |
| Potassium | 20 mmol/L | 20 mmol/L |
| Chloride | 80 mmol/L | 65 mmol/L |
| Citrate (base) | 10 mmol/L | 10 mmol/L |
| Osmolarity | 311 mOsm/L | 245 mOsm/L |
Advantages of Low Osmolarity ORS: Reduced stool output by ~20%, less vomiting, fewer IV interventions needed. Recommended by WHO since 2002 and by IAP/Government of India since 2004.
💡 Home-made ORS
1 liter clean water + 6 level teaspoons sugar + ½ teaspoon salt. Easy to remember: "6 and a half".
WHO and UNICEF recommend zinc supplementation as an adjunct to ORS since 2004 for all children in developing countries.
Benefits:
- Reduces duration of diarrhea by ~25%
- Reduces stool volume
- Decreases risk of subsequent diarrheal episodes for 2–3 months after treatment
Dose:
- Children < 6 months: 10 mg/day for 14 days
- Children ≥ 6 months: 20 mg/day for 14 days
Available as dispersible tablets dissolved in ORS or breast milk.
Continue feeding — do NOT starve:
- Breastfed infants: Continue breastfeeding on demand throughout illness AND during rehydration
- Formula-fed infants: Resume full-strength formula as soon as rehydration phase is complete (within 2–4 hours) — lactose-free formula NOT routinely required
- Weaned children: Age-appropriate soft diet as soon as rehydration is achieved — rice, roti, khichdi, curd, banana, potato
Foods to avoid:
- High-sugar drinks — carbonated drinks, commercial juices, undiluted fruit juices (worsen osmotic diarrhea)
- High-fat foods initially
- BRAT diet exclusively — inadequate nutrition; NOT recommended
- Boiled water alone — no electrolytes
Ondansetron (5-HT3 antagonist) is the only antiemetic recommended in pediatric AGE for facilitating oral rehydration when persistent vomiting prevents ORT.
Dose: 0.1–0.15 mg/kg orally or IV (max 4 mg in infants, 8 mg in older children); single dose usually sufficient.
Evidence: Reduces the need for IV hydration, decreases vomiting episodes, improves ORT success rates.
Contraindicated / not recommended antiemetics:
- Metoclopramide: Extrapyramidal side effects in children — avoid
- Domperidone: Cardiac arrhythmias (prolonged QTc) — not routinely recommended
- Promethazine: Contraindicated in children under 2 years (respiratory depression)
Antibiotics are NOT routinely used in viral AGE. They are indicated in:
| Condition | Drug of Choice | Duration |
|---|---|---|
| Shigella dysentery | Azithromycin (10 mg/kg/day × 3 days) or Ciprofloxacin (in older children) | 3–5 days |
| Cholera (V. cholerae) | Azithromycin (single dose 20 mg/kg) or Doxycycline (>8 yr) | 1–3 days |
| Typhoid (enteric fever) | Cefixime or Azithromycin (oral); Ceftriaxone (severe) | 7–14 days |
| Amoebiasis (Entamoeba histolytica) | Metronidazole (35–50 mg/kg/day in 3 doses × 5–7 days) + Diloxanide furoate (luminal agent) | 5–10 days |
| Giardiasis | Metronidazole (15 mg/kg/day × 5 days) or Tinidazole (single dose) | 3–5 days |
| Neonatal/infant sepsis diarrhea | Broad-spectrum IV antibiotics | Per culture |
🚨 Do NOT give antibiotics in:
STEC (E. coli O157:H7) — increases Shiga toxin release → precipitates/worsens HUS. Salmonella non-typhi gastroenteritis in immunocompetent children — may prolong carrier state.
- Loperamide (Imodium): Antiperistaltic — reduces intestinal motility. Contraindicated in children <2 years (ileus, toxic megacolon risk, lethal respiratory depression); also avoid in bloody diarrhea/STEC infection
- Diphenoxylate + Atropine (Lomotil): Contraindicated in children — CNS/respiratory depression
- Kaolin-pectin, Attapulgite: Not effective; may reduce ORS absorption
- Bismuth subsalicylate: Avoid in children <12 years (Reye syndrome risk)
Preferred IV fluid: Ringer's Lactate (Hartmann's solution) — physiologically closest to ECF. Normal Saline (0.9% NaCl) is acceptable if RL unavailable.
Fluid calculation for severe dehydration (WHO Plan C):
- Infants (<12 months): 30 mL/kg IV in 1 hour, then 70 mL/kg over 5 hours (total 100 mL/kg over 6 hours)
- Older children (1–5 yr): 30 mL/kg IV in 30 minutes, then 70 mL/kg over 2.5 hours (total 100 mL/kg over 3 hours)
Total fluid requirement = Deficit + Maintenance + Ongoing losses
- Deficit = % dehydration × body weight (kg) × 1000 mL
- Maintenance by Holliday-Segar formula: 100 mL/kg (first 10 kg) + 50 mL/kg (next 10 kg) + 20 mL/kg (beyond 20 kg)
- Ongoing losses: 10 mL/kg per watery stool
💡 Key point
Switch to ORS as soon as the child can drink. IV fluid is only a bridge. Avoid 5% Dextrose as sole rehydration fluid — no electrolytes → risk of hyponatremia.
Non-specific prevention:
- Hand hygiene (soap and water — especially before feeding, after toilet)
- Safe water and food handling
- Exclusive breastfeeding for 6 months (reduces AGE hospitalization risk by 50%)
- Proper sanitation and safe disposal of feces
Rotavirus Vaccines (India/Global):
| Vaccine | Type | Doses | Schedule |
|---|---|---|---|
| Rotarix (GSK) | Monovalent, oral, live attenuated (G1P[8]) | 2 doses | 6 weeks and 10 weeks |
| RotaTeq (Merck) | Pentavalent, oral, live reassortant (G1–G4, P[8]) | 3 doses | 6, 10, 14 weeks |
| Rotavac (Bharat Biotech) | Monovalent, oral, 116E strain (India-specific) | 3 doses | 6, 10, 14 weeks — in India NIP since 2016 |
| Rotasiil (Serum Institute) | Pentavalent, oral | 3 doses | 6, 10, 14 weeks |
Contraindications to Rotavirus vaccine: Severe combined immunodeficiency (SCID), history of intussusception, hypersensitivity. Maximum age for first dose: 15 weeks; all doses by 8 months (32 weeks).
🔭 Recent Advances — Exam Q&A
Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit.
Evidence-based strains with consistent benefit in AGE:
- Lactobacillus rhamnosus GG (LGG) — reduces diarrhea duration by ~1 day; best evidence in viral AGE
- Saccharomyces boulardii — reduces duration and frequency; especially useful in antibiotic-associated diarrhea
Mechanism: Compete with pathogens for mucosal attachment, produce bacteriocins, stimulate IgA secretion, enhance mucosal barrier.
Current guideline position (ESPGHAN 2014/2020): Probiotics are recommended as an adjunct (not replacement) to ORT, with moderate certainty of benefit. IAP also recommends their use.
Caution: Avoid in immunocompromised patients — risk of bacteremia/fungemia.
Racecadotril (Acetorphan) is an enkephalinase inhibitor (inhibits neutral endopeptidase) — reduces intestinal hypersecretion without affecting motility.
Mechanism: Inhibits breakdown of endogenous encephalins → reduces secretion of water and electrolytes into the gut lumen (antisecretory action).
Advantages over Loperamide: Antisecretory (not antimotility) → no risk of ileus or toxic megacolon. Safe in children.
Dose: 1.5 mg/kg three times daily until normal stools (max 7 days).
Evidence: Reduces stool output and duration of diarrhea when added to ORS. Recommended by ESPGHAN as an adjunct in children with secretory diarrhea.
Diosmectite is a natural phyllosilicate clay that acts as an intestinal mucosal protector and adsorbent.
Mechanism: Adsorbs pathogens, toxins, and bile acids; reinforces the mucous gel barrier lining the intestinal epithelium.
Evidence (meta-analyses): Reduces duration of acute diarrhea by approximately 1 day and stool frequency. Well tolerated.
ESPGHAN recommendation: Considered as a conditionally recommended adjunct to ORT in childhood AGE.
Dose: 3 g (1 sachet) dissolved in 50 mL water, given 3 times daily for 3 days in children >1 year.
Multiplex nucleic acid amplification tests (NAATs) like the BioFire GI Panel can detect 22 pathogens (bacteria, viruses, parasites) simultaneously from a single stool sample within 1–2 hours.
Advantages: High sensitivity and specificity; detects co-infections; rapid turnaround time; particularly useful in immunocompromised hosts, severe/refractory diarrhea, or outbreak investigation.
Limitations: Cannot distinguish colonization from active infection; expensive; may detect organisms of unclear clinical significance in a sick child; does not provide antibiotic sensitivity (no bacterial isolate).
Not routine for uncomplicated AGE — reserved for complex, severe, or prolonged cases.
Norovirus is now the leading cause of AGE in children in countries with high rotavirus vaccine coverage. There is currently no licensed Norovirus vaccine available globally (as of 2025).
Vaccine candidates under investigation:
- VLP (Virus-Like Particle) vaccines — no live virus; intranasal or oral formulations in Phase 2/3 trials
- mRNA Norovirus vaccine platforms are in early-phase trials
Challenges: High genetic diversity of Norovirus (multiple genotypes — GII.4 is most common), lack of long-lasting immunity, difficulty growing the virus in cell culture for vaccine production.
IV/oral Ondansetron: Multiple RCTs and meta-analyses confirm that a single dose of ondansetron in children with AGE and moderate dehydration significantly reduces vomiting, increases success of ORT, and decreases the need for IV fluids and hospitalization. It is endorsed by AAP, CPS (Canadian Pediatric Society), and ESPGHAN.
Rapid (accelerated) rehydration: Studies support giving ORS at 50 mL/kg over 2 hours (rather than 75 mL/kg over 4 hours) in children with mild-moderate dehydration in the emergency department setting, with equivalent efficacy and reduced time in ED. Rapid IV rehydration (60 mL/kg in 2 hr) also studied with good outcomes.
⚡ Key Points — Quick Revision
One-Liners for Exam
- Definition of diarrhea: ≥3 loose/watery stools in 24 hours (WHO)
- Most common cause of AGE (globally): Rotavirus (in unvaccinated); Norovirus (vaccinated populations)
- Most common bacterial cause (developing countries): ETEC
- Peak age for Rotavirus: 6 months – 2 years
- Dysentery implies: Bloody + mucoid stool → bacterial/amoebic etiology → treat with antibiotics
- Most reliable sign of dehydration: Prolonged skin turgor (>2 sec) + sunken eyes + altered sensorium (combination)
- Hypernatremic dehydration trap: Skin turgor may be normal ("doughy") despite severe dehydration
- Gold standard for dehydration assessment: Acute weight loss (% body weight)
- ORS osmolarity (WHO 2002): 245 mOsm/L (Low osmolarity: Na 75, Glucose 75)
- WHO Plan A: No dehydration → ORS 50–100 mL/loose stool at home + zinc + continue feeding
- WHO Plan B: Some dehydration → 75 mL/kg ORS over 4 hours at health facility
- WHO Plan C: Severe dehydration → IV RL 100 mL/kg (30 mL in 1 hr first if infant)
- Zinc dose: 10 mg/day (<6 months), 20 mg/day (≥6 months) for 14 days
- Safe antiemetic in children: Ondansetron only
- Antiemetics to avoid: Metoclopramide (EPR), Promethazine (<2 yr)
- Antidiarrheals to avoid: Loperamide in <2 yr; avoid in all bloody diarrhea
- Do NOT give antibiotics in: Viral AGE, STEC O157:H7, non-typhi Salmonella in immunocompetent
- HUS triad: Microangiopathic hemolytic anemia + Thrombocytopenia + AKI (post-STEC)
- Rotavirus vaccine in India (NIP): Rotavac — 3 doses at 6, 10, 14 weeks
- Probiotic with best evidence: LGG (L. rhamnosus GG) and S. boulardii
- Racecadotril mechanism: Antisecretory (enkephalinase inhibitor) — not antimotility
- BRAT diet: Not recommended — nutritionally inadequate
- Breastfeeding during AGE: Continue throughout — do NOT stop
- Lactose-free formula: NOT routinely required in AGE
- IV fluid of choice: Ringer's Lactate (NOT 5% dextrose alone)
📊 Dehydration Quick Reference
| Grade | % Weight Loss | Key Signs | Plan |
|---|---|---|---|
| None | <5% | Alert, moist mucosa, normal CRT | A |
| Some | 5–10% | Irritable, sunken eyes, dry mouth, slow turgor, CRT 2–3 s | B |
| Severe | >10% | Lethargic, very sunken eyes, unable to drink, CRT >3 s, shock signs | C |