The onset of TD usually occurs within the first week of travel but may occur at any time while traveling, and even after returning home. The most important determinant of risk is the traveler's destination. High-risk destinations are the developing countries of Latin America, Africa, the Middle East, and Asia.
Attack rates are similar for men and women.
The primary source of infection is ingestion of fecally contaminated food or water. Most TD cases begin abruptly. The illness usually results in increased frequency, volume, and weight of stool. Altered stool consistency also is common. Other commonly associated symptoms are nausea, vomiting, diarrhea, abdominal cramping, bloating, fever, urgency, and malaise.