What is the likely cause of gastrointestinal illness with symptoms of vomiting, stomach pain, nausea, gas, and diarrhea in multiple travelers?

Likely Culprit: Norovirus

The most likely cause is norovirus gastroenteritis, given the acute onset within hours of each other affecting multiple travelers, prominent vomiting lasting 3-6 hours, and the constellation of nausea, stomach pain, gas, and some diarrhea. 1

Clinical Reasoning

Why Norovirus is Most Likely

• Norovirus characteristically presents with violent vomiting and nonbloody diarrhea lasting 2-3 days or less, with associated headache and body aches 1
• The simultaneous onset in 3 out of 5 travelers within hours strongly suggests a common-source exposure (contaminated food or water) with subsequent person-to-person transmission 2
• Norovirus requires only a small viral dose to cause infection, making it highly efficient at causing outbreaks in travel groups 2
• The short incubation period of 24-48 hours and illness duration of 12-60 hours fits the clinical picture 2
• Low-grade fever occurs in approximately 40% of norovirus cases during the first 24 hours, which may or may not be present here 1

Alternative Considerations

Bacterial causes (Salmonella, Shigella, Campylobacter, E. coli) are less likely because:

• Absence of fever makes invasive bacterial disease unlikely 2, 1
• No mention of bloody stools, which would suggest bacterial dysentery 2
• Bacterial gastroenteritis typically has longer incubation periods 2

Staphylococcal food poisoning could present similarly with rapid onset and prominent vomiting, but typically resolves within 6-12 hours 3

Management Approach

Immediate Actions

• Focus on supportive care with oral rehydration therapy as the mainstay of treatment 1
• Monitor for signs of severe dehydration (altered mental status, decreased urine output, orthostatic hypotension) 1
• No stool testing is recommended for uncomplicated traveler's gastroenteritis 2, 1

When to Escalate Care

Pursue stool testing and medical evaluation if: 1, 4

• Diarrhea persists ≥14 days (consider Giardia and other parasites)
• High fever >38.5°C develops or persists beyond 24-48 hours
• Bloody stools appear
• Severe dehydration occurs despite oral rehydration attempts

Critical Pitfall to Avoid

If fever develops or persists, do not assume simple viral gastroenteritis - the combination of fever with diarrhea in travelers suggests possible invasive bacterial disease (Salmonella, Shigella, Campylobacter) or even enteric fever, which requires broader evaluation and potential antibiotic therapy 2, 4

Infection Control

• Implement strict hand hygiene among all travelers to prevent secondary transmission 2
• Norovirus spreads efficiently through both fecal-oral and airborne routes (aerosolized vomit) 2
• Environmental surfaces should be disinfected if in shared accommodations 2