Tropical diarrhea is the most common medical problem among people travelling
to the tropical and semitropical areas of Latin America, Haiti and the
Dominican Republic, southern Asia, Africa. It affects 20-50% of such
travelers. Bacterial enteropathogens cause at least 80% of traveler's
diarrhea. The most common sources of traveler's diarrhea are contaminated
food and, to a lesser degree, contaminated water. In many tropical countries,
crops are grown in soil fertilized with human excreta, thus ensuring the
widespread contamination of food with enteropathogens. Viral pathogens are
spread primarily by water, particularly during rainy seasons.
From a longer article on causes and sources of tropical diarrhea, clinical
features, prophylaxis and treatment in the New England J.of Med. 328 (1993),
1821-1827.