Partly because of an outbreak of salmonella from a Georgia plant's tainted peanuts last year, the effort to eliminate foodborne illness has not improved much, the Centers for Disease Control and Prevention reported Thursday.

"Progress has plateaued," said Robert Tauxe, the deputy director of the agency's Division of Foodborne, Bacterial and Mycotic Diseases.

Officials were looking at 2008 data from 10 states, including Georgia, through the Foodborne Diseases Active Surveillance Network, or FoodNet, which is jointly operated by the CDC, the Food and Drug Administration and the U.S. Department of Agriculture.

After improvements from the mid-1990s when FoodNet began, rates of foodborne disease such as salmonella have essentially stayed the same for the past four years, and some, such as Escherichia coli 0157, have increased slightly.

It points out the need for greater efforts and resources and better ways of tracing food once an outbreak has been detected, said David Acheson, the associate commissioner for foods for the FDA.

This is particularly true with the globalization of the food supply and the rapid distribution of food through the system, Dr. Acheson said.

For instance, it took several weeks to track an outbreak from peppers back to its source, he said.

Or sometimes the reverse is true, Dr. Acheson said, "when we're dealing with situations with peanut butter or pistachios where you know where it started, from a firm in Georgia or California, but what you don't know for several weeks is where it's all gone."

The FDA has expanded overseas to places such as China to do more testing, particularly in problem areas, Dr. Acheson said.

"I think FDA certainly needs to do more inspections," he said.

The CDC is also trying to beef up its laboratory surveillance network by increasing the capacity of some county health departments "so that outbreaks can be better detected and investigated in the first place, starting from people who become ill to determine what it is, what is the food source in that outbreak and then coordinating closely with our regulatory partners to trace it back to a source and do something about it," Dr. Tauxe said.

The plateau over the past year comes despite proactive efforts to curb foodborne illness that, for instance, have reduced the amount of broiler chicken contaminated with salmonella by more than 50 percent, said Dr. David Goldman, the assistant administrator of the Food Safety Inspection Service for the USDA.

"Why has it plateaued? Perhaps we should be grateful that it hasn't really increased," Dr. Tauxe said.