Cross-contamination has been identified by WHO and CDC as a risk-factor that could lead to foodborne illness. Some folks, me included, have suggested that we don’t know a whole lot about cross-contamination (mechanisms for transfer and how often they happen). In a study a couple of years ago, we video recorded handling practices in food service kitchens, and saw quite a bit of cross-contamination. 
And most of it was indirect – where equipment or utensils (like sinks and knives) was an intermediate that facilitated transfer.
The newest food safety infosheet, a graphical one-page food safety-related story directed at food businesses, demonstrates some of the consequences of indirect cross-contamination.
Food Safety Infosheet Highlights:
– 75 ill with salmonellosis after eating at the Tenth Hole Tea Rooms in Southsea (U.K.)
– Salmonella found in pre-cooked pasta and dishcloths, staff tested positive
– Don’t wash raw meats. Salmonella and other bugs can be sprayed up to 3 feet away by washing.