• Globalization of the food supply, particularly of perishable foods, like fresh produce
U.S. citizens can now eat fresh fruits and vegetables all year round, produced in both Northern and Southern Hemispheres. However, some fresh foods may be contaminated during picking, packaging, transport, or delivery.

•The development of new food production industries in developing nations to meet the needs of the export market
This includes growing nonindigenous fruits and vegetables that may be susceptible to contamination by indigenous microbes. For example, raspberries were recently introduced into Guatemala with U.S. support as a potentially valuable commercial crop. Some of the exported raspberries were found to be contaminated with Cyclospora, a waterborne protozoan parasite not previously associated with foodborne disease.

• Centralized processing of human and animal foods, followed by widespread distribution
If an ingredient used in an animal feed, for example, is contaminated with a strain of Salmonella, that strain can be quickly disseminated to food animals around the world. Or, if ground beef is contaminated with E. coli O157:H7 at a factory, hamburgers sold at fast-food restaurants in many different locations may transmit infection.

• Expanded U.S. market for “ethnic” foods
There is increased familiarity with—and preferences for—foods from different countries, due to international travel by U.S. citizens, the growing ethnic diversity of our population, and our many immigrant communities. A recent outbreak of typhoid fever was associated with imported frozen mamey fruit pulp, popular among Central Americans living in Florida. Outbreaks of gastroenteritis caused by antibiotic-resistant Salmonella have occurred in people who ate traditionally-prepared Mexican cheese made from raw milk and sold informally.

• Increased international travel
International tourists and business travelers often develop “traveler’s diarrhea,” caused by foodborne bacteria that generally do not affect local adults, most of whom have acquired immunity from repeated childhood exposures.