Bacterial Gastroenteritis: This is the most common cause of traveler's diarrhea, often due to consumption of contaminated food or water. Bacteria such as E. coli, Salmonella, and Shigella are frequent culprits.

Viral Gastroenteritis: Viruses like norovirus and rotavirus can also cause traveler's diarrhea, especially in areas with poor sanitation.
Giardiasis: An intestinal infection caused by the parasite Giardia lamblia, which can be contracted through contaminated water or food.
Food Poisoning: Consuming spoiled or contaminated food can lead to traveler's diarrhea, with symptoms often appearing within hours of eating.

Cholera: Although less common, cholera is a severe and potentially life-threatening cause of diarrhea that can be contracted through contaminated food or water, particularly in areas with poor sanitation.
Amoebic Dysentery: Caused by the parasite Entamoeba histolytica, this condition can lead to severe diarrhea and is more common in travelers to developing countries.
Clostridioides difficile (C. diff) Infection: While less common in travelers, C. diff can cause severe diarrhea, especially in individuals who have recently used antibiotics.

Cyclosporiasis: An intestinal infection caused by the parasite Cyclospora cayetanensis, which can be contracted through contaminated food or water.
Cryptosporidiosis: Caused by the parasite Cryptosporidium, this infection can lead to severe diarrhea, particularly in immunocompromised individuals.
Intestinal Parasites: Other parasites such as hookworm, roundworm, or tapeworm can also cause diarrhea in travelers, although these are less common causes.