(HealthDay News) -- Each year, as many as 50 percent of international travelers develop diarrhea. The condition usually occurs within the first week of travel, but may occur at any time -- even after returning home.

High-risk destinations are the developing countries of Latin America, Africa, the Middle East and Asia. The primary source of infection is ingestion of contaminated food or water.

Travelers can minimize their risk by practicing these preventive measures, courtesy of the U.S. Centers for Disease Control and Prevention:

• Avoid eating foods or drinking beverages purchased from street vendors and establishments that appear to have unclean conditions.
• Avoid eating raw or undercooked meat and seafood.
• Avoid eating raw fruits and vegetables unless you peel them.

Avoid drinking tap water, drinks with ice, unpasteurized milk, and dairy products, which also can increase your risk. Safer beverages include bottled carbonated drinks, hot tea or coffee, beer, wine and water that's been boiled or chemically treated.