Mark Thibault recently commented on foodborne illness on his "Hypercycle" blog.  Part of his post was about the cost of foodborne illness:

Gastrointestinal illnesses, also known as upset stomach, are fairly common. The main pathogens are Salmonella, E-coli, Listeria, Campylobacter (all bacteria), Rotavirus and Norovirus. Diarrhea is second only to the common cold as a cause of lost working time, with about 25 days lost from work or school each year for every 100 Americans. 4 out of 5 children under 5 will develop Rotavirus. The overall cost has been estimated at $6.9 billion for bacterial infections (Department of Agriculture) and $1 billion for Rotavirus alone. Although no estimate have been publicly released, the economic impact of Norovirus can be estimated between $4 and $8 billion, as the CDC believes that over 50% of all food-borne diseases are due to this virus.

This chart helps illustrate his point:

Foodborne Illness Cost