Investigators are mum on exactly what other vegetables are getting tracked.
Items commonly served with fresh tomatoes is the only hint Food and Drug Administration food safety chief Dr. David Acheson would give, calling it "irresponsible" to point a finger until he has more evidence that some other food really deserves the extra scrutiny.
"Tomatoes aren't off the hook," he stressed. "It's just that there is clearly a need to think beyond tomatoes."
Still, Acheson widened FDA's probe on Tuesday, activating an emergency network of food laboratories around the country in anticipation of lots of additional samples to test.
The reason is that the outbreak continues, with 869 people now confirmed having taken ill. Most troublesome, at least 179 of them fell ill in June, the latest on June 20. That is more than two months after the first salmonella illnesses appeared, meaning the outbreak is continuing weeks longer than food-poisoning specialists had expected — and suggesting the culprit is still on the market.
Over the weekend, disease detectives with the Centers for Disease Control and Prevention began interviewing people sickened in June to find out what they ate and to compare their diets with those of healthy relatives and neighbors. Officials wouldn't reveal early findings, except to say they supported the investigation's new move.
Among the possibilities FDA is exploring is whether tomatoes and other produce are sharing a common packing or shipping site where both might become contaminated, or whether multiple foods might be tainted while being grown on adjoining farms or with common water sources.
Pressure is increasing on the FDA to solve the case, with the tomato industry suffering millions of dollars in losses and pushing for Congress to investigate how the agency handled the outbreak.
But Acheson said Tuesday that there's a growing misconception in the public that if tomatoes really were to blame, the outbreak would only have lasted six weeks.
That's just not true, he said, pointing to farms that rotate harvests so as to keep producing tomatoes for months.
Tomatoes first became a suspect because of what are called "case-control" studies rapidly conducted in New Mexico and Texas, the outbreak's center, CDC food-poisoning specialist Dr. Robert Tauxe said.
Those kinds of studies compare the sick to people who are otherwise similar — in income, lifestyle, where they live — but healthy. In those initial studies, about 80 percent of the ill reported eating certain types of fresh tomatoes, far more than the healthy group did, Tauxe said. Statistically, the association was too strong to think it a coincidence.
Some food-poisoning experts say the CDC missed a key step in not taking those studies a step further and trying to trace why some of the healthy ate tomatoes without harm.
For now, the FDA continues to urge consumers nationwide to avoid raw red plum, red Roma or red round tomatoes unless they were grown in specific states or countries that the agency has cleared of suspicion. Check the FDA's Web site — http://www.fda.gov — for an updated list. Also safe are grape tomatoes, cherry tomatoes and tomatoes sold with the vine still attached.
That advice is coming under fire too because tomatoes are sent through multiple repacking and distribution sites around the country, even to Mexico and back, regardless of where they're grown. But Acheson said the advice would be fine-tuned only if new science emerges.
Even Health and Human Services Secretary Michael Leavitt expressed frustration Tuesday that the case isn't solved.
"Nothing happens fast enough when you have a problem like this," Leavitt said as he asked Congress for more funds and stronger legal powers for food and consumer safety agencies. Still, "I feel confident we will find the solution to this problem."