What is the differential diagnosis for a patient with violent vomiting, headache, body aches, and mild diarrhea that started after traveling?

Differential Diagnosis for Acute Gastroenteritis After Travel

This presentation is most consistent with acute viral gastroenteritis, specifically norovirus, which typically causes violent vomiting and nonbloody diarrhea lasting 2-3 days or less with associated headache and body aches. 1

Most Likely Diagnosis

Norovirus gastroenteritis is the primary diagnosis given:

• Violent vomiting that has now resolved (classic for norovirus) 1
• Duration of symptoms (<24 hours of active vomiting) 1
• Associated headache and body aches (constitutional symptoms common with viral gastroenteritis) 2
• Mild diarrhea (nonbloody, consistent with viral etiology) 1
• Low-grade fever is present in approximately 40% of norovirus infections during the first 24 hours 1

Other Viral Causes to Consider

Rotavirus can cause similar presentation with:

• Vomiting for approximately 3 days followed by watery diarrhea for 3-8 days 2
• However, the rapid resolution of vomiting makes this less likely 2

Adenovirus (types 40,41) typically causes:

• Longer illness duration (≥1 week), making this less likely given symptom improvement 2

Bacterial Causes (Less Likely But Important)

Food poisoning from preformed toxins should be considered:

• Staphylococcus aureus enterotoxin or Bacillus cereus cause nausea and vomiting lasting ≤24 hours 1
• Clostridium perfringens or B. cereus (long-incubation) cause diarrhea and cramping lasting 1-2 days 1
• The absence of fever and rapid improvement make these possibilities 1

Bacterial gastroenteritis (Salmonella, Shigella, Campylobacter) is less likely because:

• These typically present with fever and bloody stools 1
• Abdominal pain is usually more severe 1
• The patient lacks visible blood in stool 1

Enteric fever (typhoid/paratyphoid) must be considered in travelers with:

• Fever, headache, and body aches (present in this case) 1
• However, diarrhea is uncommon in enteric fever, and violent vomiting is not characteristic 1
• This diagnosis becomes more likely if fever persists beyond 3-5 days 1

Parasitic Causes (If Symptoms Persist)

If diarrhea continues beyond 14 days, evaluate for:

• Giardia lamblia (most common parasitic cause in travelers) 1
• Cryptosporidium, Cyclospora, Entamoeba histolytica 1, 3

When to Pursue Diagnostic Testing

Do NOT pursue stool testing at this point because:

• Most traveler's diarrhea is self-limited and does not require testing 1
• Diagnostic testing is not recommended in uncomplicated traveler's diarrhea 1

Pursue stool testing if:

• Diarrhea persists ≥14 days (test for parasites) 1, 3
• Fever develops or persists 1
• Bloody stools appear 1
• Severe dehydration occurs 1
• Recent antibiotic use within 8-12 weeks (test for C. difficile) 1, 3

Critical Management Points

Assess for dehydration immediately:

• Dehydration increases risk of life-threatening illness, especially in vulnerable populations 1
• Physical examination is the best method to evaluate hydration status 4

Supportive care is the mainstay:

• Oral rehydration therapy for mild-to-moderate dehydration 4, 5
• Resume normal diet as tolerated 6

Red Flags Requiring Immediate Evaluation

• Signs of severe dehydration (altered mental status, decreased urine output, orthostatic hypotension) 1, 2
• High fever (>38.5°C) persisting beyond 24-48 hours 2
• Bloody stools 1, 2
• Severe abdominal pain (may indicate STEC, Yersinia, or surgical abdomen) 1, 2
• Symptoms persisting beyond expected viral duration (>7 days) 2

Common Pitfalls to Avoid

• Do not empirically treat with antibiotics unless bacterial etiology is confirmed, as this can worsen outcomes in STEC infections and increase C. difficile risk 1
• Do not overlook C. difficile if the patient received antibiotics for any reason in the past 8-12 weeks, even as self-treatment for traveler's diarrhea 1, 3
• Do not assume all vomiting is benign—if symptoms worsen or new neurological symptoms develop, consider other diagnoses like meningitis or increased intracranial pressure 7