‘The Smoking Jalapeño’

August 2008

I wish I could claim the title as mine, but alas, I cannot. The correct attribution is Stephen Hedges, a reporter for the Chicago Tribune. He was reflecting on the fact that after more than 1,200 reported cases and two months of investigation, the causative strain, Salmonella enterica serotype Saintpaul, had finally been isolated directly from a food item — in this case, a jalapeño pepper.

Cases began to occur in early May, peaked in late May and early June and have since declined, according to the July 25, 2008 update from the CDC (www.cdc.gov/salmonella/saintpaul/archive/072508.html. Accessed July 30, 2008). Judging by the epidemic curve, the outbreak should be over. Almost 1,300 cases have been reported, and there are surely a larger number of unreported cases. The geographic distribution has been remarkably widespread; among the “lower 48,” only Nebraska, North Dakota, South Dakota and Wyoming have failed to report any cases. Alaska and Hawaii have escaped as well.

Here was an outbreak that should have been capable of a solution early on; it was due to a quite rare Salmonella serotype — one that had a unique genetic fingerprint. Thus, the amount of microbiologic “background noise” should have been quite small.

The investigation focused from the start on tomatoes, apparently for two reasons. First, initial food histories indicated a substantially higher rate of tomato consumption among infected people than among normal controls. Second, and perhaps more importantly, there were a dozen or more prior Salmonella outbreaks traced to the consumption of raw tomatoes. It was all too easy, therefore, to focus exclusively on tomatoes.

What proved to be most frustrating was the amount of intermixing of tomatoes grown in various states of this country as well as Latin American countries, notably Mexico. This made it virtually impossible to identify where any given tomatoes on supermarket shelves may have been grown. So concerned were the FDA investigators about raw tomatoes that on June 7, an official “warning” was released, advising consumers against eating certain kinds of raw tomatoes. Consumers and restaurants all responded, and fresh tomatoes were suddenly a vanishing part of the American diet. Cases continued to occur.

There was another small problem. Despite about 1,700 cultures, no laboratory succeeded in isolating S. enterica serotype Saintpaul from fresh tomatoes. The circle of evidence could not be closed. By late June, investigators began to look at other foods that contained tomatoes, especially salsas, peppers and cilantro. Also, the occurrence of several restaurant-associated case clusters in Texas provided helpful clues.

Then finally on July 21, the FDA announced the “smoking pepper,” a single contaminated jalapeño pepper that yielded the organism; it had been grown in Mexico and found in a distribution center in McAllen, Texas. Later, the FDA lifted its warning on tomatoes but still held out the possibility that they could have been responsible for some of the cases. Evidently, based on epidemiologic evidence, the FDA believes that only jalapeño peppers grown in Mexico are suspect; peppers grown in the United Sates are believed to be safe.

The source of the S. enterica Saintpaul in some Mexico-grown jalapeño peppers remains unknown; moreover, it is not clear how or by whom this is being further investigated. It is quite possible we will never know how this outbreak came about.

Meanwhile, to no one’s surprise, the tomato growers are asking taxpayers for compensation for their losses — to the tune of about $100 million!

Criticism of investigation

There has been a great deal of criticism of this investigation — some of it appropriate and some of it unjustified. Among the chief criticisms have been the initial, almost exclusive focus on tomatoes, the generally slow pace of the investigation and the multiplicity of federal agencies involved. There are 12 such federal agencies responsible for food safety, with the FDA in the lead. One can only imagine the coordination difficulties and the turf issues that must have played a role. There seems to be general agreement, however, on the need to reexamine the processes, to identify the gaps and to streamline future outbreak investigations.

Probably the biggest problem identified was tracing back the sources of various foodstuff, tomatoes in particular. Not only was there generally poor record-keeping, but tomatoes from many different farms and even many different areas were mixed and processed together, thus making any kind of “trace-back” virtually impossible. Furthermore, by the time the problem was recognized, many tomato fields were no longer in production. A system to enhance the FDA’s ability to trace the source of contaminated foods or foods believed on the basis of epidemiologic evidence to be contaminated is already taking shape within an intergovernmental working group.

Jalapeños were hard to pinpoint because they are used in many dishes, and people simply don’t remember eating them. As noted by the CDC’s Bob Tauxe, food histories won’t detect something people don’t remember eating.

From all of this may come some further progress in the technology of food safety. Two technologies may play a role here: high-pressure processing and irradiation. High-pressure processing involves literally squeezing bacteria to death, hopefully including any pathogens present. The trick is to be able to do this without destroying the texture of the food being processed. This technology is already being used to extend the shelf life of avocadoes and derivative products such as guacamole.

Irradiation might also play a role. Irradiated meats have been on the market for years, and this technology has played a key role in eliminating Escherichia coli from ground beef. Public acceptance of irradiated products has gained ground, albeit painfully slowly.

Only time will tell what has been learned from this outbreak and its investigation.