How Did The Tomato Scare Start?

If they don’t know the source of the recent salmonella scare, then how did they trace it back to the tomato - specific varieties no less - as the culprit? The reports I’ve read never go into detail about the origins of this.

They generally start by identifying who got sick, where they got sick, and what they bought within the last 48-72 hours that could have made them sick. They then identify commonalities between the known patients: What is/are the common food(s) that they all ate? Did they buy it from the same place? If not, do the places they bought the foodstuffs from all have the same supplier? If so, where did the supplier get it from? If not, do the various suppliers buy from the same farm/importer/central distributor? And so on down down the line until they can pinpoint what, where, when, and possibly how much, as well as what it was that that spoiled the foods – pesticides? Contaminated groundwater? Contaminated additives or preservatives (where applicable)? Etc.

The process takes weeks if not months, especially for an outbreak the size of this one, which so far has affected over 1,000 people across 41 states and has been traced to both tomatoes and possibly jalapeno peppers as well.

The CDC always publishes details on things like this:
Investigation of Outbreak of Infections Caused by Salmonella Saintpaul

Not for Salmonella. salmonellosis has a longer incubation period than some gastrointestinal disorders so you need to look at a much longer dietary history.

What is interesting about this outbreak is that it is, in a sense, an artifact of recent advances in laboratory and information technology and recent huge investments in communicable disease surveillance. Outbreaks such as this or even multiple similar outbreaks could have occurred frequently throughout the last century and no one would have ever been aware of them.

One thing the CDC has not highlighted and science reporters have missed is that, despite all the laboratory and media attention, the number of reported cases of salmonellosis in the United States this year is DOWN from last year meaning that the chance of the average person getting salmonellosis from eating their usual diet is has been LOWER the first half of this year than last. As of week 27 of 2008, there were 15721 cases reported whereas at the same time last year there were 16595 reported.

Here are the cumulative totals for salmonellosis from Table II in the MMWR from week 27 for the past 7 years: 15721, 16595, 15148, 14546, 14478, 14153, 14191. Given the population increase during that time and assuming that the sensitivity of salmonellosis reporting has not declined, I’d say that the incidence of salmonellosis has remained fairly constant.