Hunt for source of salmonella-tainted tomatoes continues

The search for the source of salmonella-tainted tomatoes drags on, federal officials said today, even after they cleared two more states and part of Mexico over the weekend.

Health experts are still unsure if the outbreak originated at a farm or at a packing station, David Acheson, the Food and Drug Administration’s associate commissioner for foods, told reporters in a conference call today.

Acheson said a cluster of nine cases, all from the same geographical region and involving similar types of tomatoes, was “the most fruitful lead to date.” Acheson confirmed Friday that the nine people contracted salmonella after eating at two restaurants from the same chain, but would not name the chain or give any identifying characteristics, such as the location of the restaurants.

“We are focusing on that fairly heavily,” he said. “It’s a very solid lead for us to take back on the trace-back.”

But Acheson would not say if the cases are the same nine that the Chicago Department of Public Health identified as salmonella cases linked to tomatoes eaten at a restaurant in May.

And though health officials are also following other cases, “there is no one chain of restaurants or a grocery chain that accounts for all of the cases” in the outbreak, said Dr. Ian Williams, chief of the OutbreakNet Team at the Centers for Disease Control and Prevention.

The rare Salmonella Saintpaul strain has caused 228 reported infections nationwide since mid-April and has led to at least 25 hospitalizations. The FDA eliminated several areas, including Baja California in Mexico, New Mexico and Indiana, as potential sources over the weekend.

The search has focused on southern and central Florida and Mexico, though the FDA said tomato shipments from Mexico and northern Florida are safe if they are accompanied by a certificate from the areas’ respective agriculture departments.

Though the agency has stepped up its sampling of tomatoes, Acheson said that none of the tested fruit came back positive for salmonella. Williams said the CDC has heard no reports of salmonella infections in Mexico.

Consumers and farmers alike have criticized health officials for the slow pace of the investigation, which the FDA says is unavoidable because of the wide scope of the outbreak, the shaky memories of victims and the difficulties of tracing tomatoes. As a result, wary shoppers have shunned the fruit and growers have suffered plunging sales as they destroy stalled shipments of the rapidly ripening produce.

Acheson said he did not know how much the FDA has spent on the investigation.

Consumers should continue to steer clear of any fresh Roma, plum or standard round tomatoes that are not from the 37 states that have been excluded as the source of the outbreak, according to the FDA. California is not associated with the outbreak. Any tomatoes with an indeterminate origin should not be eaten.

The agency said cherry and grape tomatoes and tomatoes still attached to the vine are fine.

Though Williams said the outbreak is still classified as ongoing, with the most recent reported illness on June 1, many of the tomatoes harvested during the initial outbreak period have exceeded their shelf life and are likely no longer in circulation.

“There’s a lot of aggressive work going on,” Acheson said. “I’m optimistic that this cluster [of nine cases] will help us, but as we’ve found before, especially with tomatoes, things can become disconnected even when you think you’re almost there.”

 tiffany.hsu@latimes.com