As the number of cases in an ongoing salmonella outbreak climbed past 800 Friday, federal health officials said that they might never find the cause -- and that tomatoes might not be the culprit after all.
The news was greeted with resignation and a degree of anger from shoppers and growers who have seen millions of tomatoes taken off grocery shelves in the last month.
Of 1,700 domestic and international tomato samples collected for investigators so far, none has tested positive, said David Acheson, associate commissioner with the Food and Drug Administration.
Though fresh tomatoes have a "strong association" with many of the cases and remain a top suspect, he said health officials have not confirmed that the fruit carried the rare Salmonella Saintpaul strain.
Dr. Patricia Griffin of the Centers for Disease Control and Prevention would not divulge whether any other produce was being seriously investigated, only saying that it would "continue to keep an open mind about the possible source."
The most recent reported incident of the illness was June 15, and for each reported case there are likely to be more that have gone undetected, she said.
Some consumers said that they were becoming increasingly wary -- and weary -- of produce in general.
While clutching a shopping bag filled with red round tomatoes at a produce stand in Grand Central Market downtown, Jose Valadez, 39, of El Monte -- who happens to be a produce clerk at a Ralphs supermarket -- said he was worried that his children might get sick from unsafe fruits and vegetables.
"It's all very confusing, since I was under the impression that the problem was solved," he said. "Now I don't know what to think. I'm frustrated with the information being given out, and with the sense that agencies aren't coming clean."
Griffin said 810 people across 36 states and Washington, D.C., had fallen ill since mid-April and that at least 95 had been hospitalized.
Tomato growers were startled by the news that tomatoes may not be to blame for the outbreak. "It's a shocking revelation that many innocent people who took devastating losses may have taken a fatal blow unnecessarily," said Tom Nassif, chief executive of the Western Growers Assn., whose members cultivate about half of the nation's produce.
"The entire country is suffering in every tomato-growing area," Nassif said. "Demand and the market price is down, and sales could be affected for many years to come."
"We hope the rest of the produce industry will not be painted with this broad brush," United Fresh Produce Assn. spokeswoman Amy Philpott said. "We've lost a lot of money, but we have done it in the interest of public health."
Far from being ruled out as the source of the salmonella, tomatoes that could be carrying the bacteria might still be entering the market because of large growing areas, long harvesting periods or unsanitary warehouse conditions, Acheson said.
Last week, health agencies said they tracked some of the implicated tomatoes to farms in Florida and Mexico, but officials stressed that contamination could have happened in transit or at a packing station.
The FDA has cleared 41 U.S. states, including California; several Mexican states; and parts of Florida
"The longer this goes on, the less likely it's all originating from a single farm source," Acheson said.
"It's possible this investigation will not produce a smoking gun," Acheson said. "We need to look at all possibilities. We need to reexamine all the information."
Food safety experts said the agencies were doing the best they could with limited staff and budgets and, to stay on the safe side, were not ruling out other produce.
"There are going to be a lot of theories, but I would hesitate to try to second-guess the investigators," said Caroline Smith DeWaal, food safety director at the Washington-based Center for Science in the Public Interest. "The people in the field probably know a lot more than they're telling us, but they need a very high level of certainty."
The FDA said its consumer advisory remained the same -- that Roma, plum and red round tomatoes from cleared states and grape, cherry and vine tomatoes from all areas were safe to eat.
Yasmin Tarver, 34, a social worker from Los Angeles, said she did not blame health agencies for the long investigation.
As she emerged from a downtown El Pollo Loco with bagged chicken and avocado salsa on the side, she said she's stopped eating fresh tomatoes and only uses ketchup from bottles she owned before the outbreak began.
"I have no control over needing to go to the grocery store to buy food, but until I can grow my own -- which I don't see happening -- I guess I'll just have to be extra mindful," Tarver said.