Federal health officials haven't yet traced the source of salmonella-tainted tomatoes but, amid an outcry from farmers, are clearing innocent crops as fast as possible. "We're getting very close" to identifying the outbreak's source, Dr. David Acheson of the Food and Drug Administration told reporters Wednesday. The outbreak, which has sickened 167 people in 17 states since April, is not over even though it has been two weeks since the last confirmed case of a person falling ill, said Dr. Ian Williams of the Centers for Disease Control and Prevention. That's because state and local health departments still are investigating possibly more recent infections.

The FDA has warned consumers against eating certain raw tomatoes: red plum, red Roma or round. Grape and cherry tomatoes or tomatoes still attached to the vine aren't linked to the illnesses.

Also ruled safe are tomatoes from more than 30 states or countries, including part but not all of major producer Florida, where some counties have been cleared but not others. The FDA can rule out as suspects farms and distributors that weren't harvesting or selling when the outbreak began. It is directing consumers to its Web site - - for updated lists of safe regions.http://www.fda.gov

State Agriculture (web|news) commissioners from the Southeast, meeting in Kentucky, blasted the FDA for harming the sale of untainted crops.

"The FDA needs to work with the states to pinpoint the source of the outbreak and eradicate it without unnecessarily harming producers whose products are not affected by the outbreak," Kentucky Agriculture Commissioner Richie Farmer said.

The FDA vigorously defended its consumer-protection warnings.

"We have gone overboard to try to inform consumers which tomatoes were not part of this outbreak," Acheson said.

It takes a long time to even tell an outbreak has begun, much less solve it. People with food poisoning don't always go to the doctor, or have a stool sample analyzed - and when they do, getting laboratory test results can take two to three weeks. Then health officials must spot a pattern of illness.

Health officials in New Mexico were first to alert the CDC (web|news) to a brewing problem on May 22. They had a cluster of salmonella cases, including seven of a rare subtype called Salmonella Saintpaul. The next day, New Mexico officials posted to a government database called PulseNet these cases' genetic fingerprint, allowing the CDC to check whether this same strain of Saintpaul was infecting people elsewhere.

It was, in Texas and other states, with the first illness dating back to April 16, Williams said. CDC then began the painstaking questioning of patients to see what they had in common. On May 30, FDA formally joined the investigation, and the next day established a link with tomatoes. Initial consumer warnings were aimed at a few states, until the FDA went national last weekend.

Salmonella sickens about 1.4 million people a year. But outbreaks aren't on the rise, although public attention may make it seem so, Acheson said.

"We don't want to stay quiet and have consumers get sick. The downside of that is consumers say, 'Oh, the system is in crisis,'" he said. "It's not getting worse."