Norovirus and salmonella were the leading causes of foodborne illness in 2006, according to a report issued Thursday by the Centers for Disease Control and Prevention (CDC).

That year, there were 1,270 reported foodborne disease outbreaks, which resulted in 27,634 illnesses and 11 deaths. Of the outbreaks, 621 had a confirmed single cause, with norovirus (54%) and salmonella (18%) responsible for most cases.

Norovirus infection usually occurs when infected food handlers fail to wash their hands adequately after using the toilet. Salmonella infection usually occurs when foods that have been contaminated with animal feces are eaten raw or insufficiently cooked.

The foods associated with most outbreaks were poultry (21%), leafy vegetables (17%) and fruits/nuts (16%).

“Determining the proportion of outbreak-associated cases of foodborne illness due to the various food commodities is an important step,” says Patricia M. Griffin, MD, chief of the CDC′s Enteric Diseases Epidemiology Branch. “Identification of particular food commodities that have caused outbreaks can help public health officials and the food industry to target control efforts from the farm to the table.”

But Dr. Griffin offers an important caveat: While this report is useful, some outbreaks are not detected, investigated or reported because many states lack the resources to handle testing.

Photo by James Gathany/CDC