What causes enteritis?

Causes of Enteritis

Enteritis is primarily caused by infectious pathogens, with bacterial infections being the most clinically significant, followed by viral and parasitic agents. 1

Bacterial Causes

• Bacterial pathogens are major causes of enteritis, particularly:

  • Campylobacter - one of the most common bacterial causes 1, 2
  • Salmonella species - including non-typhoidal and typhoidal strains 1
  • Shigella - associated with more severe, bloody diarrhea 1
  • Escherichia coli (particularly STEC) - can cause serious complications 1
  • Clostridium difficile - especially following antibiotic use or in healthcare settings 1
  • Vibrio cholerae - associated with post-infectious IBS in 16.5% of cases 1

• Bacterial enteritis often causes more severe symptoms than viral infections, including:

  • Fever
  • Bloody diarrhea
  • Abdominal pain
  • More pronounced inflammation 1

Viral Causes

• Viral agents are the most common overall cause of enteritis, particularly:
  • Norovirus - the leading cause of gastroenteritis outbreaks 1
  • Rotavirus - significantly reduced in children due to vaccination 3
  • Other viral pathogens generally cause less mucosal damage than bacterial agents 1

Parasitic Causes

• Parasitic infections causing enteritis include:
  • Giardia lamblia - causing giardiasis with symptoms of diarrhea, abdominal cramps, bloating 4
  • Cryptosporidium - extremely chlorine-tolerant and difficult to control in institutional settings 1
  • Cyclospora and Cystoisospora - more likely to cause severe disease in immunocompromised patients 1
  • Microsporidia - particularly problematic in immunocompromised hosts 1

Risk Factors and Special Populations

• Travel-related risk factors:

  • Recent travel to endemic areas increases risk of specific pathogens 1, 4
  • Consumption of contaminated food or water 4
  • Approximately 10% of traveler's diarrhea is caused by parasitic infections 1

• Host factors increasing risk:

  • Immunocompromised status - particularly HIV infection, transplant recipients 1
  • Advanced age (>65 years) - associated with up to 20-fold increased risk 1
  • Malnutrition or obese BMI - both increase susceptibility 1
  • Active inflammatory bowel disease - increases risk of opportunistic infections 1

• Medication-related factors:

  • Immunosuppressive medications - particularly combination therapies 1
  • Antibiotics - disrupt normal gut flora, predisposing to C. difficile 1
  • Specific immunosuppressants carry different risks: corticosteroids (fungal), thiopurines (viral), anti-TNF agents (fungal and mycobacterial) 1

Post-Infectious Complications

• Post-infectious irritable bowel syndrome (PI-IBS):

  • Develops in 10.1% of patients within 12 months after infectious enteritis 1
  • Risk remains elevated (14.5%) even beyond 12 months 1
  • 4.2-fold increased risk compared to uninfected individuals 1
  • Bacterial infections carry higher risk than viral infections 1
  • C. difficile infection associated with PI-IBS in up to 25% of cases 1

• Other post-infectious complications:

  • Post-infectious functional dyspepsia (PI-FD) - occurs in approximately 9% of cases 1
  • Lactose intolerance - common after infectious enteritis 3
  • Higher risk of overlapping PI-FD and PI-IBS in children than adults 1

Diagnostic Considerations

• Diagnostic approach should be guided by:

  • Presence of fever or bloody diarrhea - warrants evaluation for specific bacterial pathogens 1
  • Duration of symptoms - persistent symptoms beyond 14 days suggest parasitic infection 4
  • Recent antibiotic exposure - increases suspicion for C. difficile 5
  • Travel history - critical for identifying endemic pathogens 1, 4

• Multiple stool examinations may be necessary for detecting certain pathogens like Giardia 4, 5

• Immunocompromised patients may present atypically and require more extensive testing 5