Aug. 25--Earlier this summer, a Food and Drug Administration warning about particular varieties of raw tomatoes being linked to a nationwide salmonella outbreak kept them off supermarket shelves, your favorite submarine sandwich and the salad you planned on making with dinner when the news broke.
The warnings, which devastated the tomato industry with multi-million dollar losses and fed the news cycle for weeks, were eventually lifted, only to be replaced by similar warnings about certain varieties of hot peppers.
It certainly wasn't the first time consumers had been faced with a food scare. In 2006, it was spinach. Earlier this year, cantaloupes from a Honduran company were implicated with a nationwide cluster of salmonella cases.
The United States is said to have one of the safest food supplies in the world, but many criticized the handling of the investigation by the FDA and the cooperating Centers for Disease Control and Prevention, saying the investigation was too slow and caused unnecessary public panic.
Why was the outbreak a several-month ordeal? Because for all the touting of the U.S. food supply as safe, it's also complex. And because of large-scale food production and distribution, it becomes increasingly difficult to trace products back to the source.
Earlier this month, the CDC issued a report updating the salmonella outbreak investigation. In addition to explaining that the main source of the outbreak was likely raw jalapeno and serrano peppers grown, harvested or packed in Mexico, the report also helps the public understand the long and tangled series of investigative work that led to this conclusion. Here's how it happened:
¦ The illness:Beginning in late April, illnesses caused by a similar strain of salmonella -- Salmonella Saintpaul -- are reported in several states, the most cases from Texas and New Mexico. Clinics that saw patients had samples of the bacteria sent to their states' department of health laboratories for analysis, where it was concluded that the samples had the same DNA fingerprint, meaning they shared a source. The information is then forwarded to the federal government.
This process can be slow-going, taking as long as three weeks. Often, it takes one to three days just for the salmonella to have a noticeable effect on the body. It can take another one to five days just for the patient to see their health care provider, and then one to three days for the diagnosis to be made. Additional shipping time to get the bacteria to the state laboratories for analysis and the time spent conducting the tests explain why it took until June for the FDA to issue any kind of warning about a possible outbreak.
Collecting patient data is complicated because not everyone who may have the illness goes to the doctor and is tested. Even when it is determined that infection has occurred, people often have difficulty remembering what foods they ate and when and do not usually have samples of the food leftover that can then be tested.
Tracing the source to tomatoes: Investigators compared the diets of those who were not ill with the diets of Texas and New Mexico residents who were determined to have suffered from Salmonella Saintpaul exposure in May. It was determined that eating raw tomatoes was common among those with the salmonella strain.
In the meantime, the agency looked to pinpoint the source -- tracking the produce back to the restaurant or retailer where the ill people obtained the tomatoes, then to the distribution center where the tomatoes were packed, and then yet one step further back to where the food was harvested and grown. Investigators look for identifying details such as labeling and lot numbers to try to determine when the tomatoes were bought or prepared and how the food was handled both in the distribution centers and in the fields. That information is not always clear or available in written, traceable forms.
On June 3, the FDA issued its first warning about consuming raw red Roma, plum and round tomatoes and products containing them to those in Texas and New Mexico. By June 7, the warning was expanded to nationwide, when cases in all the other reporting states showed similar DNA fingerprints.
The FDA then issued warning updates several times a week as the investigation focused in, providing a list of states and nations where tomatoes grown there were deemed to be safe. In most of those places, tomatoes simply weren't yet in season and so they couldn't have been responsible for the outbreak. Other tomatoes that weren't reportedly consumed by those struck with the outbreak, such as grape, cherry and on-the-vine tomatoes, were never included in the warnings.
A turn in the investigation: Suspicion began to broaden beyond tomatoes when new cases of Salmonella Saintpaul were being reported even after the FDA issued its warning about tomato consumption. A larger study looking at those nationwide who became ill in June revealed that those salmonella sufferers were more likely to have eaten raw tomatoes, raw jalapeno peppers and raw cilantro. Because those ingredients are often eaten together -- in salsa -- it was difficult to pinpoint which ingredient was causing those illnesses.
Clusters of the disease were studied, and though in some cases tomatoes and jalapenos were eaten together, in other clusters, jalapeno peppers alone were consumed.
Once again, using the same kind of trace-back investigating, an FDA sample of a pepper taken from a distribution center in McAllen, Texas came up positive for Salmonella Saintpaul. Those peppers were then traced to a farm in Mexico and an FDA lab found the salmonella strain in a serrano pepper and an agricultural water sample taken there. A state laboratory in Colorado also found the strain in a jalapeno pepper provided by a patient who had become ill after eating the peppers.
The FDA issued a warning about eating raw Serrano and jalapeno peppers in late July, which still stands and applies only to raw jalapeno and serrano peppers grown in Mexico.
Jennifer Gish can be reached at 454-5089 or jgish@timesunion.com.
On the Web
To learn more about the Salmonella Saintpaul investigation, visit the FDA Web site at http://www.fda.gov/oc/opacom/hottopics/tomatoes.html.
-----
To see more of the Albany Times Union, or to subscribe to the newspaper, go to http://www.timesunion.com.
Copyright (c) 2008, Albany Times Union, N.Y.
Distributed by McClatchy-Tribune Information Services.
For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.