Differential Diagnosis for Diarrhea after Traveling to Mexico with Close Contacts Sick Too

• Single most likely diagnosis:
  • Traveler's diarrhea (likely caused by bacteria such as E. coli, Salmonella, Shigella, or Campylobacter) - This is the most probable diagnosis given the context of recent travel to Mexico and the presence of similar symptoms in close contacts, suggesting a contagious cause.
• Other Likely diagnoses:
  • Viral gastroenteritis (e.g., norovirus, rotavirus) - These viruses are highly contagious and can cause outbreaks, especially in settings where people are in close proximity, such as during travel.
  • Parasitic infections (e.g., Giardiasis) - Although less common than bacterial causes, parasitic infections can also be acquired during travel, especially if the individual consumed contaminated water or food.
• Do Not Miss diagnoses:
  • Cholera - While less common in travelers, cholera is a severe and potentially life-threatening condition that requires immediate medical attention. It's particularly concerning in areas with poor sanitation.
  • Food poisoning from toxins (e.g., Staphylococcus aureus, Bacillus cereus) - These can cause severe symptoms and have a rapid onset, often related to the consumption of specific contaminated foods.
• Rare diagnoses:
  • Cyclosporiasis - This parasitic infection can cause prolonged diarrhea and is associated with consuming contaminated food or water, particularly in tropical regions.
  • Brucellosis - Although rare, this zoonotic infection can be acquired through contact with infected animals or their products, and it can present with gastrointestinal symptoms among others.
  • Intestinal amoebiasis - Caused by Entamoeba histolytica, this parasitic infection can lead to dysentery or chronic diarrhea and is more common in travelers to endemic areas who have consumed contaminated food or water.