Gastroenteritis: Causes, Symptoms, Treatment, and Prevention

Gastroenteritis ("stomach flu") is inflammation of stomach and intestines causing diarrhea, vomiting, abdominal pain. Not influenza.

Etiology

• Viral (70–80%): Norovirus (adults), rotavirus (children), adenovirus, astrovirus, sapovirus.
• Bacterial: Salmonella, Campylobacter, Shigella, E. coli (ETEC, EHEC), C. difficile, Vibrio.
• Parasitic: Giardia, Cryptosporidium, Entamoeba histolytica, Cyclospora.

Transmission

• Fecal-oral: contaminated food/water, person-to-person, fomites.
• Zoonotic: animal contact, undercooked meat/seafood.

Symptoms

• Watery diarrhea (non-bloody usually viral; bloody suggests bacterial/parasitic)
• Nausea, vomiting
• Abdominal cramps
• Fever (low-grade viral; high bacterial)
• Malaise, myalgias, headache

Complications

• Dehydration, electrolyte imbalance (↑ risk: infants, elderly, immunocompromised)
• Hemolytic uremic syndrome (HUS) with STEC (O157:H7).
• Post-infectious IBS, reactive arthritis.

Management

• Oral rehydration (ORS): WHO formula—cornerstone.
• Diet: Early refeeding (complex carbs, lean protein, yogurt); avoid fatty/spicy.
• Antiemetics: Ondansetron (children >6 mo) reduces vomiting, IV need.
• Antidiarrheals: Loperamide (adults only; avoid bloody/febrile).
• Antibiotics: Only for specific bacterial/parasitic causes (culture-guided).
• Zinc (children): Reduces duration/severity.
• Probiotics: L. rhamnosus GG, S. boulardii modest benefit.

Prevention

• Handwashing (soap, 20 sec).
• Rotavirus vaccine (infants).
• Safe food/water practices.
• Exclude ill food handlers/children from daycare.