Three weeks after the Food and Drug Administration warned consumers to avoid certain types of tomatoes linked to the salmonella outbreak, people are still falling ill, says Robert Tauxe with the Centers for Disease Control and Prevention.
The latest numbers as of Monday afternoon were 851 cases, some of whom fell ill as recently as June 20, says Tauxe, deputy director of the CDC's division of foodborne diseases.
The CDC launched a new round of interviews over the weekend. "We're broadening the investigation to be sure it encompasses food items that are commonly consumed with tomatoes," Tauxe says.
If another food is found to be the culprit after tomatoes were recalled nationwide and the produce industry sustained losses of hundreds of millions of dollars, food safety experts say the public's trust in the government's ability to track foodborne illnesses will be shattered.
"It's going to fundamentally rewrite how we do outbreak investigations in this country," says Michael Osterholm of the Center for Infectious Disease Research and Policy at the University of Minnesota. "We can't let this investigation, however it might turn out, end with just the answer of 'What caused it?' We need to take a very in-depth look at foodborne disease investigation as we do it today."
At a news conference Friday, representatives of the FDA and the CDC were more forceful in saying that they aren't sure tainted tomatoes caused the outbreak of salmonella saintpaul, a fairly rare strain. Previous statements had been more vague.
Over the weekend, the tide of opinion among epidemiologists, produce companies and food safety officials also began to turn in that direction.
Tomatoes couldn't have caused an outbreak that has stretched from early April to late June, says Jim Prevor, editor of Produce Business magazine. "There's not a field in the world" that produces that long, he says.
If not tomatoes, what else? "Something that people find difficult to remember but which is always served with tomatoes," says Tauxe.
That would put salsa, jalapeño peppers, green onions and cilantro at the top of the list of potential culprits, says Doug Powell, director of the International Food Safety Network at Kansas State University in Manhattan, Kan.
Food safety experts caution that outbreaks are very difficult to trace back to their source, especially tomatoes, which are often mixed and matched at the packing plant to get uniform sizes and ripeness.