Acute Gastroenteritis Overview

Acute Gastroenteritis and Dehydration

• Acute gastroenteritis (AGE) is the passage of excessively liquid and/or frequent stools for a few days, up to one week. Diarrhea lasting more than 3 weeks is no longer considered acute.
• AGE can be accompanied by vomiting, fever, cramping abdominal pain, loss of appetite, and diaper rash in young children.
• Worldwide, there are 3-5 billion cases of AGE, and nearly 1.6 million deaths occur each year in children under 5 years old. The annual hospital admission rate for AGE is approximately 7 per 1,000 children. Children with poor nutrition are at increased risk of complications. AGE is a major cause of death in developing countries.
• Etiology:
  • Viruses (~70%): Rotaviruses, Noroviruses (Norwalk-like viruses), Enteric adenoviruses, Caliciviruses, Astroviruses, Enteroviruses
  • Protozoa (<10%): Cryptosporidium, Giardia lamblia, Entamoeba histolytica
  • Bacteria (10-20%): Campylobacter jejuni, Non-typhoid Salmonella spp, Enteropathogenic E. coli, Shigella spp, Yersinia enterocolitica, Shiga toxin-producing E. coli, Salmonella typhi and S paratyphi, Vibrio cholerae
  • Helminths: Strongyloides stercoralis
• Viral Infections:
  • Damage small bowel enterocytes, causing low-grade fever and watery diarrhea, sometimes with blood.
  • Rotavirus infection is seasonal, peaking in late winter but can occur year-round.
  • Rotavirus strains vary geographically and seasonally.
  • Peak age for infection is 6 months to 2 years.
  • Transmission is fecal-oral or respiratory.
  • Usually lasts 2-3 days.
• Bacterial Gastroenteritis:
  • C. jejuni and Salmonella spp: Invade the lining of the small and large intestine, triggering inflammation.
  • Shiga toxin-producing E. coli or Shigella: Cause hemorrhagic colitis (severe bloody diarrhea).
  • Enteric fevers (S. typhi and S. paratyphi): Cause severe illness in children, involving high fever, diarrhea, constipation, leucopenia, and sometimes, CNS involvement (encephalopathy).
  • Vibrio cholera: Cholera toxin causes excessive chloride and water secretion in the small bowel, resulting in "rice water" stools, high in sodium chloride, but without mucus or blood.
• Food Poisoning:
  • Caused by ingestion of toxins from bacteria in contaminated food or drink.
  • S. aureus, C. perfringens, B. cereus: Common causes, often associated with undercooked or improperly stored cooked/processed meats and seafood.
  • Rapid onset of vomiting/diarrhea (usually 12-24 hours).

Diagnosis

• Primarily based on the patient's history and physical examination.
• Factors considered include recent contact with others with gastroenteritis, travel history to endemic areas, antibiotic or other diarrhea-inducing drug use.
• Nature and frequency of stool and vomitus.
• Symptoms of dehydration (fever, etc).
• Oral intake and urine output observed.
• Lab tests are usually not necessary in uncomplicated acute gastroenteritis.
• Supplementary lab tests might include stool exam, serum electrolytes, or stool cultures (indicated in cases of dysentery, i.e., bloody diarrhea). Stool antigen tests for viruses (Rota virus, Adeno virus, Norwalk agent) and protozoa (Giardia, E. histolytica) could also be considered.

Assessment of Dehydration

• Primary morbidity associated with AGE is dehydration and electrolyte imbalance.
• Assessment goals include identifying patients needing treatment intensity variation or hospitalisation.
• Guidelines (CDC '92, AAP '96) categorize dehydration severity: Mild (<3% body weight loss); Moderate (3-9% body weight loss); Severe (>10% body weight loss, shock or near shock).
• Clinical signs of dehydration assessed include decreased mental status, thirst, heart rate, and pulse quality, breathing pattern, eye dryness, mouth and tongue moisture, skin turgor, capillary refill time, and urine output.
• Recent weight loss is a key indicator of dehydration severity.
• Prolonged capillary refill (>2 seconds), abnormal skin turgor, absent tears, and dry oral mucosa are indicators of possible dehydration.

Treatment of Dehydration

• Treat dehydration, not the AGE itself, as it is generally self-limiting.
• Oral rehydration solution (ORS) is used when possible.
• Intravenous (IV) fluids are used for cases requiring more intensive treatment (severe dehydration).
• Maintain nutrition; keep the patient eating and drinking normally, but avoid foods causing discomfort if they are present.

Physiological Basis for Oral Rehydration Therapy (ORT)

• Effective ORT depends on sodium and glucose co-transport at the intestinal brush border.
• This mechanism remains efficient even with severe diarrhea.

WHO/UNICEF Standard ORS vs Home Recipe

• Composition of ORS solutions (Sodium, chloride, glucose, potassium, and citrate).
• Standard ORS solutions have precise electrolyte and carbohydrate concentrations.
• Home remedies can deviate significantly in electrolyte and carbohydrate content.

Therapy of Minimal Dehydration

• If the patient can tolerate drinking without nausea, manage at home.
• For children under 10kg, give 60-120mL ORS for each episode; 120-240mL for those above 10kg.
• Encourage age-appropriate feeding/breastfeeding.

Therapy of Mild Dehydration

• Children who do not tolerate oral fluids, need observation, admission for observation.
• Small frequent feedings, continued breast feeding.
• ORS (50-100 mL/kg over 3-4 hours) given orally or via NGT, if refusal.
• Avoid drinks high in sugar (e.g., cola, sports drinks) as these can worsen symptoms.

Therapy of Severe Dehydration

• Severe dehydration is a medical emergency demanding immediate intravenous (IV) fluid administration.
• Administration of 20mL/kg normal saline within 30-40 minutes until improved perfusion.
• Maintenance of hydration via 100 mL/kg ORS over 4 hours.
• Frequent monitoring of vital signs (heart rate, blood pressure, capillary refill, urine output, urine concentration).
• Transition to oral rehydration therapy once consciousness/perfusion improves.
• Administering the remaining estimated deficit via the oral route.

When Hospitalization is Indicated

• Severe dehydration (body weight loss > 9%).
• Mild or moderate dehydration with difficulties with ORS administration or caregiver's inability to manage complications at home.
• Intractable vomiting/ORS refusal.
• Worsening diarrhea despite adequate ORT.
• Dehydration in children ≤6 months or those with abnormal conditions.
• Progressive course with uncertain diagnosis.

Frequent Complications of Acute Gastroenteritis

• Dehydration (with potential electrolyte imbalances like hyponatremia, hypokalemia, hypernatremia)
• Metabolic acidosis
• Carbohydrate intolerance (lactose, glucose)
• Secondary lactase deficiency
• Malnutrition (increased risk of reinfection).

Diet and Drugs During Acute Diarrhea

• Breastfeeding/formula should continue.
• Probiotics can help shorten the duration of AGE (e.g. Rotavirus).
• Early reintroduction of solid foods and complex carbohydrates recommended.
• Antibiotic use is generally not indicated in viral or uncomplicated bacterial AGE; indicated only in severe bacterial infections (cholera, shigella, septicemia, dysentery). Antidiarrheal or antimotility agents are not recommended.
• Some antiemetics (without extrapyramidal side effects) may help reduce vomiting duration/frequency.

This quiz focuses on acute gastroenteritis (AGE), including its symptoms, causes, and global impact, particularly on children. Learn about the various etiological agents involved, such as viruses, bacteria, and protozoa. Understand the significance of AGE in public health and the associated risks, especially in developing countries.