More than 1,000 people in 41 states and the District of Columbia have now been sickened in the nation’s salmonella outbreak, in what officials said Wednesday was the largest food-borne outbreak in the last decade. And some food safety experts this week tied problems in tracing the source of the contamination to what they say are shortcomings in the Bioterrorism Act of 2002.

Federal investigators have now linked at least some of the outbreak to fresh jalapeños, Dr. Robert Tauxe of the Centers for Disease Control and Prevention said, though they have not ruled out tomatoes.

But officials have still not pinpointed the source of the contamination. Nor do they know the country or state where the tainted produce was grown, despite a rule issued by the Food and Drug Administration under the bioterrorism law that was intended to give federal officials a way to respond immediately to threats to the nation’s food supply.

The rule requires importers, processors and distributors to keep track of where they buy produce and where it goes. A major hurdle facing investigators in this outbreak, however, is that processors frequently repack boxes of tomatoes to meet a buyer’s demands. In doing so, officials said, they are not required to record the tomatoes’ farm, state or even country of origin.