Virus Transmission via Food
Dean O. Cliver

Viruses have emerged as causes of foodborne disease, according to data compiled by the Centers for Disease Control and Prevention. During 1983-87 in the United
States, Norwalk virus was the fifth leading cause of foodborne disease among outbreak-associated illnesses; hepatitis A virus was the sixth; and other viruses (principally rotaviruses) were tenth (Bean et al., 1990). By 1988-1992, the most recent period for which data have been issued, Hepatitis A virus had risen to the fourth leading cause and Norwalklike
viruses first appeared on the top 10 list as the ninth leading cause (Bean et al., 1996).

The numbers of reported foodborne illnesses are fewer than actually occur because the CDCs passive data collection system records only illnesses occurring as outbreaks, rather than those occurring sporadically. Hepatitis A, which is notoriously under reported in the United States (Cliver, 1985), is the only foodborne viral disease in which official reporting is mandatory for all diagnosed cases. Thus, records of the incidence of the other viral diseases are certain to be less accurate. And, just as with Norwalk-like viruses, other new viral agents are likely to appear among the top 10 causes of foodborne disease in future compilations.

Link: http://members.ift.org/NR/rdonlyres/A59805EA-5938-45A8-B24B-BF5CAC2E2A7F/0/virustransmissionviafood.pdf

I guess for Hep A you can get an immunization if you are traveling to a country in which food preparation standards are low.

Otherwise it's common sense; Wash your hands after using the toilet, wash uncooked food before eating and heat cooked food through properly. Maybe also, wash hands before eating and after sneezing into them.