2008 United States salmonellosis outbreak

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Fresh jalapeño peppers are likely responsible for much of the salmonellosis outbreak

The 2008 United States salmonellosis outbreak began in the spring of 2008 when hundreds of people throughout the United States fell ill after consuming contaminated food. The U.S. Food and Drug Administration currently believes that the contaminated food products responsible are fresh jalapeño and serrano peppers from Mexico, and perhaps raw tomatoes. Fresh cilantro is also under investigation. The FDA and the Centers for Disease Control and Prevention narrowed their investigation to certain farms in Mexico that they believed were responsible for the contaminated produce.

Salmonellosis[edit]

CDC map of cases per million of Salmonella Saintpaul by state

From April 10 to July 31, 2008,[1] the rare Saintpaul serotype of Salmonella enterica caused at least 1329 cases of salmonellosis food poisoning in 43 states throughout the United States and in the District of Columbia. It was the largest reported salmonellosis outbreak in the United States since 1985. New Mexico and Texas were proportionally the hardest hit, with 56.9 and 21.3 reported cases per million, respectively.[2][3] The greatest number of reported cases have occurred in Texas (508 reported cases), New Mexico (112), Illinois (116), and Arizona (57). Some other significantly impacted states include Maryland, Oklahoma, Kansas, Arkansas, and Nevada which have been collectively affected by 118 reported cases.[4] All of the above-mentioned states suffered more than five reported cases per million.[5] Additionally, five cases were reported in residents of Canada, four of whom appeared to have been infected after traveling to the United States.

There were at least 257 reported hospitalizations linked to the outbreak, leading to at least one death, and the outbreak may have been a contributing factor in at least one additional death.[6] The CDC maintains that "it is likely many more illnesses have occurred than those reported." If applying a previous CDC estimated ratio of non-reported salmonellosis cases to reported cases (38.6:1), one would arrive at an estimated 52,826 illnesses from this outbreak, and 173 estimated cases per million throughout the United States.[7]

Type of contaminated food[edit]

A sign posted at a Havelock, North Carolina Burger King telling customers that no tomatoes are available due to the outbreak.

Based on an initial case control study, the FDA and the CDC had maintained that the Salmonella was spread through raw tomatoes. The study showed that more than 80 percent of infected case subjects recalled consuming "fresh, raw tomatoes" or foods that may have contained fresh tomatoes. Only around 68 percent of control subjects recalled consuming the same.[8][9] However, inconsistencies in the survey results and the broad geographical and temporal distribution of cases led federal agencies to suggest the possibility that the Salmonella might have been spread through other "food items that are commonly consumed with tomatoes."[10] According to James Prevor, Editor of Produce Business, the extended period of new onsets of salmonellosis precludes the possibility that a specific tomato crop could be solely responsible for the outbreak.[11] That leaves the possibilities open that multiple tomato crops (possibly in different areas) were somehow concomitantly contaminated at various points of origin, multiple crops from the same area were contaminated by a single environmental factor (such as the water supply), contamination of tomatoes from various crops has been occurring at a central location along the distribution chain (such as during repacking), or some food other than tomato is responsible for the outbreak.[12] According to Dr. Douglas Powell, Director of the International Food Safety Network, possible suspects aside from tomatoes include salsa, jalapeño peppers, green onions, and cilantro.[13]

Throughout the end of June and beginning of July, the FDA has been changing its position regarding the source or sources of the Salmonella. It first admitted the possibility that foods "commonly consumed with tomatoes" might be possible suspects in the outbreak, though it declined to elaborate with specifics. Days later, it commented on specific suspects aside from fresh tomatoes: fresh serrano peppers, fresh cilantro, fresh bulb onions, fresh scallions, and fresh jalapeño peppers. The FDA still maintained, however, that tomatoes were the prime suspect. A couple of days later, the FDA began to focus on jalapeño peppers above other non-tomato suspects. Most recently, the FDA has disclosed that jalapeño peppers are now the main suspects in the outbreak, and that "the accumulated data from all investigations indicate that jalapeño peppers caused some illnesses but that they do not explain all illnesses." It has narrowed its list of suspects to fresh jalapeño peppers, raw tomatoes, fresh serrano peppers, and fresh cilantro. The FDA now maintains with confidence that tomatoes are not responsible for at least some of the illnesses. The CDC has stated that some illness clusters involved people who were certain that they ate foods with jalapeño peppers but not tomatoes, and other clusters were vice-versa. The CDC considers it most likely that contaminated tomatoes, jalapeños, and serrano peppers have all been responsible for the outbreak.

According to the FDA, types of tomatoes likely affected with Salmonella include red plum, red Roma, and round red tomatoes. The FDA writes that "types of tomatoes not linked to any illnesses are cherry tomatoes, grape tomatoes, and tomatoes with the vine still attached," and the CDC agrees that these types of tomatoes are "not the likely source of this outbreak." The FDA website provides a list of areas from which it has deemed tomato farms not to be the source of the outbreak.[14]

On July 18, 2008, the FDA lifted its warnings regarding tomato consumption, given that hardly any tomatoes from winter crops are still in circulation. On July 21, after discovering a single contaminated pepper in a load imported from Mexico, the FDA recommended that consumers throughout the United States avoid eating any fresh jalapeño peppers, regardless of the source. On July 25, the FDA announced that American grown peppers are not considered a risk to consumers. On July 30, the after tracing the outbreak strain to a Mexican farm, the FDA revised its recommendations again and warned all consumers to avoid jalapeño and serrano peppers from Mexico. People who would be in the most danger if infected with Salmonella (infants, the elderly, and those with compromised immune systems), should be especially careful to avoid eating fresh jalapeño and serrano peppers from Mexico.

Source of the contamination[edit]

As of July 31, 2008, the CDC has sent 39 people into the field to work with other health officials in investigating the outbreak. The exact sources of the contaminated food are not yet known. The time frame of the outbreak had led the FDA to suspect that a source or sources of the outbreak may be among tomato farms producing winter crops in either of the following areas:

  • Parts of Mexico, such as the State of Sinaloa, which exports over 300 million pounds of winter tomatoes to the U.S. via the Arizona border. Tomatoes from Sinaloa enter the U.S. through the hardest hit region of the southwest, which has suffered over half of the total reported cases in the outbreak. By contrast, tomatoes from Baja California, which have been listed by the FDA as "not associated with the outbreak," are exported to the relatively unaffected California.[15]
  • The southern and east-central regions of Florida. Southern and central Florida produce the majority of domestically consumed winter tomatoes, though only two cases of food poisoning have actually been reported in Florida - and one of those involved a Florida man who had eaten a raw tomato in New York.[6][16]

As of July 31, the latest reported illness onset occurred on July 12, and the latest estimated illness onset occurred on July 25. Illness onsets well into July suggest that fresh winter tomatoes are not the only source of the outbreak. In response to the continuing progression of illness onset dates, the CDC has proposed that a contaminated farm might have switched from tomato production to jalapeño production in the middle of the outbreak, causing crops of both types of foods to become contaminated. Jalapeño peppers, a food strongly suspected in the outbreak by the FDA, are primarily grown throughout Mexico, Texas, and New Mexico.

Contaminated pepper samples[edit]

On July 21, 2008, the FDA released a notice that the outbreak strain of Salmonella Saintpaul was found on a sample of jalapeño pepper from the McAllen, Texas produce importer/distributor Agricola Zaragoza, Inc. Agricola Zaragoza is a small distributor with only $600,000 in annual sales and three employees. It distributes only jalapeños and tomatillos,[17] the latter of which is not a suspect in the outbreak. No other samples, swabs, or tests taken at the facility have tested positive for Salmonella.

The contaminated pepper sample in question was imported from Mexico, and it is from a load that had been distributed to Texas and Georgia beginning on June 30.[18] No other peppers from the same load have yet been found to be contaminated. The means by which the pepper became contaminated is unknown. Between June 30 and July 12, there have been approximately 40 reported new illness onsets, representing three percent of total reported illness onsets. The number of illnesses thought to be associated with Mexican peppers from Agricola Zaragoza is undisclosed. Peppers from that distributor are the main suspects in an illness cluster involving a restaurant in Minnesota.

On July 29, a jalapeño pepper bought at a Wal-Mart in Montezuma County, Colorado, tested positive for the outbreak strain of Salmonella. Brian Grubbs, a Colorado man who was hospitalized for salmonellosis, is suing Wal-Mart for allegedly selling him contaminated peppers that got him sick in early July.[19]

On July 30, the FDA announced that it found samples of the outbreak strain of Salmonella in samples of serrano peppers and groundwater at a Mexican farm in Nuevo León. That same farm also supplied jalapeños to a packing facility in Mexico that did business with Agricola Zaragoza. Mexico's Agriculture Ministry is protesting the findings of the FDA, claiming that a soil sample was taken after the harvest and was not "scientifically valid."[20]

A different farm in Tamaulipas actually supplied the contaminated peppers found at Agricola Zaragoza. Results from FDA samples taken at that farm are pending,[21] and Mexican investigators have already found Salmonella on samples taken in Tamaulipas.[22]

Health officials have not yet indicated any positive Salmonella cultures from other samples (aside from a load of basil from Mexico[23] and loads of jalapeño and serrano peppers imported from Mexico,[24][25] none of which were found to be contaminated with the particular strain of Salmonella responsible for the outbreak).

Tracebacks[edit]

The FDA has posted on its website that "the agency has been able to trace the pathway of some tomatoes from the point of purchase (e.g. supermarket) or consumption (e.g. restaurant) to each point on the distribution chain down to certain farms in Mexico and Florida." In a press conference on June 20, the FDA elaborated: "What the traceback has done is take us back to a number of different farms in Florida and in Mexico.... [W]e've got several farms in both Florida and Mexico and those are the places along with their associated distribution chain that we are going to be getting into as quickly as possible." At the very same press conference, however, the FDA also stated: "Right now all of the traceback data that we have point to this being Mexico or Florida. Currently we do not believe it's both."

Notably, the FDA states that "there's no clear indication that there's any obvious crossover point" where tomatoes from both Mexico and Florida could have been contaminated at the same place. Dismissing the possibility of coincidence of outbreaks from two independent distribution chains as "very unlikely from a natural perspective," the FDA also insists that there is "nothing to suggest that this [food poisoning outbreak] is deliberate." The FDA expects to find that the contaminated tomatoes have been coming from only one area. This expectation is based in part on the FDA's consultations with the United States Department of Agriculture and the United States Department of Homeland Security, neither of which support the conclusion that tomatoes were deliberately poisoned.[26]

The FDA now thinks that tomatoes are responsible for only part of the outbreak, at most. The agency is no longer advising caution regarding tomato consumption, given that winter tomatoes are generally no longer in circulation.

Criticism of the FDA[edit]

James Prevor, Editor of Produce Business, has criticized the FDA for maintaining a list of areas where crops "have not been associated with the outbreak," because if tomatoes have in fact been contaminated elsewhere along the supply line, the FDA's list of safe farm areas would be inappropriate and misleading to consumers.[11] Charles H. Bronson, Agriculture Commissioner of the State of Florida, also indicated that repacking could be responsible for Salmonella contamination. Bronson said that there is a "99.99 percent" chance that the Florida tomato farms are not the source of the Salmonella outbreak.[16]

Prevor has also criticized the FDA for refusing to disclose data on whether subjects generally recalled eating suspected foods from restaurants or from retail stores: "Retail and restaurants often have completely different products with a completely different supply chain." For example, mature green winter tomatoes, which are primarily distributed to the foodservice market, are dominated by Florida producers. Vine ripe winter tomatoes, which are distributed to both the foodservice and retail markets, usually come from Mexican producers.[27] "All this information is not confidential," Prevor writes concerning data on the origins of purchase. "There is no reason not to release it." [28] At least three Mexican restaurants (two Adobo Grills and one Los Tres Amigos) in Illinois have been publicly identified by the Chicago Department of Public Health and the Madison County Health Department as responsible for clusters of the outbreak, despite the FDA's nondisclosure stance.[29][30] According to unnamed sources close to the investigation, most illness clusters in the outbreak involve Mexican restaurants.[31]

Earlier in the investigation, some produce industry insiders expressed doubt that fresh produce is to blame for the outbreak. They pointed to the absence of Salmonella on all of the tested produce samples to date, as well as divergent results from produce tracebacks. They also said that the extended time frame of new sicknesses made it unlikely that either raw tomatoes or fresh jalapeños, the government's two main suspects, could be solely responsible. Some have looked to cross-contamination at restaurants as a more probable cause of the outbreak. Contaminated foods such as raw chicken could have spread the Salmonella to fresh salsa at restaurants. Customers would not have become ill from contaminated chicken once it was cooked, but they might have become ill from the raw produce that had contacted raw chicken.[32]

Others suggested that processed foods such as canned tomatoes and canned jalapeños might have been responsible for the outbreak. Health officials generally do not consider processed foods high-risk suspects in food outbreaks, as the canning and bottling processes are supposed to kill any bacteria. Nevertheless, the FDA and the CDC were surprised in 2007 by outbreaks from Salmonella contamination in pasteurized peanut butter[33] and from Clostridium botulinum contamination in improperly pasteurized canned chili.[34] Will Steele, President and CEO of Frontera Produce, said that "the outbreak is probably related to processed goods and [the FDA is] looking in the wrong closets."[35]

The FDA's recommendation that consumers stop eating any fresh jalapeños, regardless of their origin, has elicited more disapproval from the produce industry. Criticism of the FDA's decision comes on the grounds that there was only a solitary positive sample among numerous negative samples both at the distribution facility and at many other farms and facilities. Additionally, Agricola Zaragoza is a small distributor that imports from a known source in Mexico and distributes peppers to limited parts of the country.[36] Four days after making the recommendation not to eat any fresh jalapeños, the FDA announced that peppers grown in the United States are indeed safe to eat.

See also[edit]

References[edit]

  1. ^ Centers for Disease Control and Prevention (2008-07-16). "Interpretation of Epidemic Curves During an Active Outbreak". 
  2. ^ "New Mexico Department of Health Home Page".  The outbreak was concentrated on both sides of the northern part of the Arizona-New Mexico border.
  3. ^ Texas Department of State Health Services, News Updates
  4. ^ "Cases infected with the outbreak strain of Salmonella Saintpaul, United States, by state".  For some states, such as Arizona and California, the CDC has recently revised the tally of confirmed illnesses downward.
  5. ^ "Incidence of cases of infection with the outbreak strain of Salmonella Saintpaul, United States, by state".  Seventeen other states, aside from the eight mentioned above, have each been affected by 10 or more reported cases.
  6. ^ a b August 12, 2008: Investigation of Outbreak of Infections Caused by Salmonella Saintpaul | Salmonella CDC
  7. ^ Voetsch, et al. (2004-04-15). "FoodNet Estimate of the Burden of Illness Caused by Nontyphoidal Salmonella Infections in the United States". Clinical Infectious Diseases, 2004; 38:S3.  The CDC has cautioned that in a widely publicized outbreak, the multiplier for estimated illnesses may be smaller; they stated that an outbreak's publicity may prompt more sick people to go to their physicians and give stool samples for Salmonella testing. The CDC also estimates that there are around double the number of Salmonella hospitalizations than the number reported. In this case, that would be an estimated 514 hospitalizations from the current outbreak.
  8. ^ [1]
  9. ^ Weise, Elizabeth (June 18, 2008). "How modern science and old-fashioned detective work cracked the salmonella case". USA Today. Retrieved April 22, 2010. 
  10. ^ Salmonella Blog (2008-06-30). "CDC's Tauxe Says Salmonella Saintpaul Outbreak Investigation Now Looking Beyond Tomatoes". Retrieved 2008-06-30. [dead link]
  11. ^ a b Jim Prevor's Perishable Pundit
  12. ^ http://www.fda.gov/bbs/transcripts/2008/tomato070108.pdf
  13. ^ USA Today (2008-06-30). "CDC broadens its investigation of salmonella outbreak". Retrieved 2008-06-30. 
  14. ^ Salmonella Saintpaul Outbreak
  15. ^ Lauran Neergaard (2008-06-13). "More illnesses linked to bad tomatoes". San Diego Union-Tribune. 
  16. ^ a b Susan Salisbury (2008-06-26). "State ag chief urges precise tomato IDs". Palm Beach Post. Retrieved 2008-06-26. 
  17. ^ [2]
  18. ^ The Associated Press: FDA finds salmonella strain in jalapeno pepper[dead link]
  19. ^ "Man who says he got salmonella from jalapeños sues Wal-Mart". Denver Post. August 3, 2008. 
  20. ^ Fox, Maggie (July 31, 2008). "FDA says Salmonella strain found on Mexican farm". Reuters. 
  21. ^ Shin, Annys (July 31, 2008). "Mexican Farm Tied to Salmonella Outbreak". The Washington Post. Retrieved April 22, 2010. 
  22. ^ http://www.coalingarecord.com/articles/2008/08/03/ap/health/d9294g800.txt
  23. ^ FDA: Salmonella found in basil grown in Mexico
  24. ^ http://www.charlotte.com/109/story/717746.html
  25. ^ eFoodAlert.com: Avocados And Peppers From Mexico Recalled
  26. ^ "Transcript for FDA Media Briefing: Salmonella Outbreak Involving Certain Type of Tomatoes". 2008-06-20.  "What the traceback has done is take us back to a number of different farms in Florida and in Mexico.... [T]here's no clear indication that there's any obvious crossover point [where tomatoes from both Mexico and Florida could have been contaminated at the same place].... I don't want to give the impression that we think even remotely this is deliberate. I put that out there not to raise concerns but simply to complete the picture for you. Because now that we have narrowed this down to two tracks - two pathways that the tomatoes began their life in Florida or they began their life in Mexico and they tracked through and we're looking at the whole pathway there is the obvious question -- could it have happened in two places at once? Very unlikely from a natural perspective. That raises the question of was it deliberate? Absolutely no indication it was deliberate. And I want to continue to emphasize that. We've got nothing to suggest that this is deliberate."
  27. ^ "North American Greenhouse Tomatoes Emerge as a Major Market Force". April 2005. 
  28. ^ "Plea For CDC To Release Sickness Details And Origin Of Purchase". 2008-07-03. 
  29. ^ "City IDs salmonella cluster - chicagotribune.com". Chicago Tribune. 
  30. ^ STLtoday - Salmonella outbreak in Wood River
  31. ^ Annys Shin and Simone Baribeau (2008-07-08). "Deconstructing Salsa In Search of Salmonella". Washington Post. 
  32. ^ "Lukewarm Indictment of Jalapeños: Solving Outbreak Requires Thinking Outside the Box". Perishable Pundit. 2008-07-10. 
  33. ^ Weise, Elizabeth (February 16, 2007). "Salmonella outbreak, rare in peanut butter, stuns health officials". USA Today. Retrieved April 22, 2010. 
  34. ^ Tainted chili cans bursting with botulism - Diet and nutrition - MSNBC.com
  35. ^ Mira Slott (2008-07-10). "Reality On The Border: Businesses Suffer At Hands Of FDA". Perishable Pundit. 
  36. ^ Jim Prevor's Perishable Pundit