Acute gastroenteritis

Disease Description (Causes and Symptoms)

• Definition: Acute gastroenteritis is a disease primarily characterized by diarrhea and vomiting, caused by acute inflammation of the gastrointestinal mucosa due to pathogens such as viruses, bacteria, and parasites.
• Causes: Rotavirus, norovirus, Escherichia coli (E. coli) strains (enterotoxigenic and enteropathogenic), Salmonella, Shigella (dysentery), Campylobacter, parasites, and others. Routes of infection include contaminated food or water, contact between patients, and unhygienic food preparation.
• Pathophysiology (brief): Pathogens or toxins irritate or invade the intestinal mucosa, causing malabsorption, secretory diarrhea, and mucosal inflammation (potentially with bloody diarrhea). Some viruses (e.g., rotavirus) cause malabsorption by damaging the villi of the small intestine.
• Main symptoms: Diarrhea (watery or bloody), vomiting, abdominal pain and bloating, fever, dehydration (dry mouth, decreased urination, lethargy), headache, muscle aches, and others. The severity of symptoms varies depending on the cause, the patient's age, and underlying diseases.

Treatment

• Basic principles

  • Fluid and electrolyte replacement is key: In mild cases, oral rehydration (ORS: oral rehydration solution); in moderate or more severe cases, or when ORS is not possible due to vomiting, intravenous fluids (isotonic crystalloid solutions) are administered.
  • Focus on symptom control and prevention of complications.

• Drug treatment

  • Oral rehydration solution (ORS): First-line treatment for both children and adults.
  • Intravenous fluids: Used for severe dehydration, persistent vomiting, or suspected shock.
  • Antiemetics: When vomiting is severe and oral intake is impossible (e.g., ondansetron) — follow the indications for use in children.
  • Antidiarrheal agents: Loperamide and similar drugs may be used to relieve symptoms in adults, but are contraindicated or require caution in cases of high fever, bloody diarrhea, severe systemic symptoms, or in children (risk of worsening when used for infectious diarrhea).
  • Antibiotics: Not generally used for all cases of acute diarrhea. Consider in the following cases:
    • Confirmed or strongly suspected bacterial infection (e.g., Shigella, Vibrio, severe Campylobacter infection, cholera, etc.)
    • High fever, bloody diarrhea, or severe systemic symptoms
    • High-risk groups for complications, such as immunocompromised or older adults
    • Selection according to regional resistance patterns and guidelines (targeted treatment based on test results)
  • Antiparasitic agents: Use appropriate medication when protozoa (such as amoebae) are identified.

• Procedures/Surgery

  • Ordinary gastroenteritis is treated non-surgically. Complications (e.g., intestinal perforation) are rare.

• Lifestyle management and precautions

  • Drink sufficient fluids (ORS is recommended), rest, and limit greasy foods and dairy products until symptoms improve.
  • Practice thorough hand hygiene and avoid consuming contaminated food or water.
  • Resuming meals: When vomiting and diarrhea improve, start with small amounts of soft food.
  • Criteria for hospitalization: Severe dehydration, electrolyte abnormalities, inability to take fluids orally due to persistent vomiting, hemodynamic instability, or severe findings in infants, young children, or people with underlying diseases.

• Prevention

  • Wash hands, consume safe drinking water and food, and thoroughly cook food.
  • Rotavirus vaccination is recommended for children (according to national and age-based recommendations).

• Complications

  • Dehydration (mild → moderate → severe), electrolyte abnormalities (such as hypokalemia), metabolic acidosis, shock, renal failure (from severe dehydration), hemolytic uremic syndrome (HUS; particularly with enterohemorrhagic Escherichia coli infection), and subsequent functional gastrointestinal disorders (e.g., post-infectious irritable bowel syndrome).

Checklist Before an Outpatient Visit (Including Sample Questions)

• Items to prepare

  • List of medications being taken (including prescription drugs, over-the-counter medications, and supplements)
  • Recent test results (if available)
  • Symptom diary: time of onset and progression, number and amount of diarrheal episodes (including watery, bloody, or mucus-containing stool), number of vomiting episodes, amount of food intake, urine output (whether it has decreased compared with baseline), and whether there is a fever and the highest temperature
  • Travel history and recent meals (raw food or communal food service), and whether there has been contact with a hospital or long-term care facility
  • Underlying diseases (chronic diseases and whether immunosuppressive treatment is being received); for children, changes in feeding status and sleep patterns

• Information to provide at the outpatient visit (items to record in advance for the doctor's evaluation)

  • Time of symptom onset and progression (improvement/worsening)
  • Changes in urine output and fluid intake
  • Whether similar symptoms are present among household members, at work, or at school
  • Whether antibiotics have recently been administered

• Sample questions (questions patients can use during a medical consultation)

  • "Is my fluid intake currently sufficient? How should I replenish fluids at home?"
  • "Do I need antibiotics? If so, which medication should I take and for how long?"
  • "When can I start eating again? What foods should I eat first?"
  • "How long will I remain contagious after returning home? How long do I need to remain isolated or stay away from school?"

General Sample Questions to Ask the Doctor

• "What pathogen is suspected as the cause of my current symptoms (vomiting, diarrhea, fever, etc.)?"
• "Are tests needed (stool culture, PCR, antigen testing, electrolyte testing, etc.)?"
• "Can fluid therapy be done at home, or do I need to be hospitalized?"
• "What are the side effects of this medication (the prescribed antibiotic, antiemetic, etc.)?"
• "What is the expected recovery period, and how can I prevent recurrence?"

Disease-Specific Sample Questions

1. "There is blood and a high fever accompanying the diarrhea. Should I start antibiotics immediately, or should I wait for the test results?"
2. "For infants and young children, how much ORS should be given per day, and when should I take them to the hospital?"