What causes vomiting and diarrhea?

Causes of Vomiting and Diarrhea

Vomiting and diarrhea are most commonly caused by viral gastroenteritis, particularly norovirus in adults and rotavirus in unvaccinated children, followed by bacterial and parasitic infections, with specific pathogens identifiable based on clinical presentation patterns. 1

Common Infectious Causes

Viral Causes (Most Common)

• Norovirus: Leading cause of viral gastroenteritis outbreaks

  • Characterized by acute onset, vomiting and nonbloody diarrhea lasting 2-3 days
  • Low-grade fever may be present during first 24 hours in 40% of infections 1
  • Highly contagious through person-to-person contact, contaminated food/water, or aerosolization during vomiting

• Rotavirus: Primary cause in young children (especially before vaccine introduction)

  • Now less common due to rotavirus vaccine implementation
  • Causes more severe and prolonged illness than norovirus 1

• Other viral agents:

  • Adenovirus (especially serotypes 40 and 41): Causes diarrhea more prominently than vomiting, often with respiratory symptoms
  • Astrovirus: Incubation period 24-36 hours, illness lasting 1-4 days
  • Calicivirus: Incubation period 1-3 days, illness lasting about 4 days 1

Bacterial Causes

• Salmonella: Most common cause of hospitalization and death from foodborne illness in the US 1

  • Associated with abdominal pain, fever, and sometimes bloody diarrhea

• Campylobacter: Common bacterial cause with abdominal pain and sometimes bloody stools 1

• Shigella: Causes dysentery with bloody diarrhea and fever 1

• Escherichia coli (STEC): Particularly E. coli O157:H7

  • Often presents with severe abdominal pain and bloody stools
  • Usually not febrile at presentation 1

• Clostridium difficile: Most common identifiable infectious cause in long-term care facilities

  • Associated with recent antibiotic use 1

• Toxin-producing bacteria:

  • Staphylococcus aureus enterotoxin: Causes nausea and vomiting lasting ≤24 hours
  • Bacillus cereus: Short-incubation emetic syndrome (vomiting) or long-incubation syndrome (diarrhea and abdominal cramping lasting 1-2 days) 1

Parasitic Causes

• Giardia lamblia: Common cause of persistent diarrhea
• Cryptosporidium species: Associated with chronic diarrhea
• Other parasites: Cyclospora cayetanensis, Cystoisospora belli, Entamoeba histolytica 1

Clinical Presentation Patterns

The pattern of symptoms can help identify the likely pathogen:

1. Vomiting predominant, short duration (≤24 hours):

   • Likely Staphylococcus aureus or Bacillus cereus toxin ingestion 1

2. Vomiting with nonbloody diarrhea (2-3 days):

   • Likely norovirus 1

3. Bloody diarrhea with abdominal pain:

   • Consider STEC, Salmonella, Shigella, Campylobacter, Yersinia, or Entamoeba histolytica 1

4. Persistent diarrhea (>14 days):

   • Consider parasitic infections (Cryptosporidium, Giardia) 1
   • May also indicate post-infectious irritable bowel syndrome

5. Diarrhea with recent antibiotic use:

   • Strongly suggests Clostridium difficile infection 1

Diagnostic Approach

When evaluating a patient with vomiting and diarrhea:

1. Assess for warning signs:

   • Visible blood in stool
   • Fever (higher temperatures suggest bacterial etiology)
   • Severe abdominal pain
   • Duration >7 days
   • Recent antibiotic use
   • Recent travel
   • Immunocompromised status

2. Consider testing based on clinical presentation:

   • Most acute, self-limited episodes don't require laboratory testing
   • Testing is warranted for severe, prolonged, or bloody diarrhea 1
   • For suspected outbreaks, follow public health department guidance 1

Treatment Considerations

1. Hydration is the cornerstone of management:

   • Oral rehydration therapy for mild to moderate dehydration
   • Intravenous fluids for severe dehydration or inability to tolerate oral intake 1

2. Antimicrobial therapy:

   • Generally not indicated for viral gastroenteritis or most cases of bacterial diarrhea
   • May be considered for specific bacterial infections based on severity and patient factors
   • Avoid antimicrobials in suspected STEC infections due to potential harm 1

3. Antiemetics:

   • Use with caution as they may mask progressive ileus or gastric distention 2
   • Ondansetron may be considered for severe vomiting but monitor for adverse effects

4. Avoid antidiarrheal agents:

   • Not recommended in infectious diarrhea, especially in children
   • May prolong bacterial shedding and worsen certain infections 1

Prevention

• Hand hygiene with soap and water (alcohol-based sanitizers are less effective against norovirus and C. difficile)
• Proper food preparation and storage
• Avoidance of high-risk foods
• Rotavirus vaccination for infants
• Isolation of symptomatic individuals, especially in institutional settings 1

Remember that most cases of vomiting and diarrhea are self-limited viral infections requiring only supportive care, but careful assessment for warning signs of more serious illness is essential.