In August 2022, the U.S. Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), and state partners conducted an outbreak investigation into a multistate outbreak of Salmonella Typhimurium linked to cantaloupe.

However, the public was not told about the outbreak until a few days ago.  Here are the numbers:

  • Total Illnesses: 88
  • Hospitalizations: 32
  • Deaths: 0
  • Last Illness Onset: September 11, 2022
  • States with Cases: Georgia (1), Illinois (5), Indiana (17), Iowa (39), Kentucky (3), Michigan (3), Minnesota (4), Missouri (2), Ohio (3), South Carolina (1), Wisconsin (10)

This is the explanation from the CDC why the outbreak this cantaloupe was not announced at the time it occurred:

A challenging part of communicating about an ongoing foodborne outbreak is deciding when to issue an outbreak notice. CDC works to balance the need for releasing information quickly with the need for an accurate, specific, and actionable message. CDC issues outbreak notices during foodborne outbreaks if there is an ongoing risk to the public and an actionable message for consumers or retailers.

CDC did not post an outbreak notice on the 2022 Salmonella outbreak linked to melons. By the time the source of the outbreak was identified, the contaminated melons were no longer available for sale in stores or in people’s homes. CDC reviewed FDA’s constituent update and supports the release of information about the 2022 outbreak to make the public aware of the findings from the investigation.

The outbreak response investigation found:

  1. In August 2022, CDC notified FDA about a multistate cluster of Salmonella Typhimurium illnesses with a potential signal for melon exposures. The cases were geographically distributed in the U.S. upper Midwest.
  2. The isolates in this cluster of illnesses were within 7 alleles / 11 single-nucleotide polymorphisms (SNPs) of two FDA soil swab samples collected from a 2020 outbreak investigation in Indiana. As a part of the 2022 investigation, FDA and state partners collected multiple samples, but none of the resulting isolates were a definitive match to the 2022 outbreak strain.
  3. FDA’s 2022 traceback investigation identified 11 points of service, of which 8 traced back to a common packinghouse. Although a common packinghouse was identified, there was no convergence to a single shipment of products, and therefore three farms that supplied the common packing house were identified as potential sources of cantaloupe.

As a result of the traceback, FDA conducted investigations in Indiana at all three farms, their common packinghouse and nearby public lands. Salmonella positive environmental samples were found at each location, but none of the resulting Salmonella isolates conclusively matched the outbreak strain by whole genome sequencing (WGS). 

No cantaloupes were recalled, and no public warning was issued due to the implicated products no longer being on the market.

Download the Full Report (PDF 14MB)

The U.S. Food and Drug Administration (FDA) has released a report on its investigation of the Salmonella Typhimurium outbreak that caused 88 reported illnesses and 32 hospitalizations in the U.S. between July and September 2022. The FDA worked with the U.S. Centers for Disease Control and Prevention (CDC) and state partners to investigate the outbreak, which was linked through epidemiology and traceback to cantaloupe grown in Southwest Indiana during the summer of 2022. The report released today includes an overview of the traceback investigation, investigation results, and various factors that potentially contributed to the contamination of cantaloupe with Salmonella.

As a result of the traceback, FDA conducted investigations in Indiana at three farms, their common packinghouse and nearby public lands. Salmonella positive environmental samples were found at each location, but none of the resulting Salmonella isolates conclusively matched the outbreak strain by whole genome sequencing (WGS). Although the investigation did not result in identification of a specific microbial source or route that resulted in this outbreak, the agency identified Salmonella spp. in on-farm, post-harvest, and off-farm environments.

In light of the investigational findings, FDA highlights the following recommendations and requirements applicable to firms, such as growers of melons and similar produce:

  • Review current conditions and practices to determine whether they are adequate or if additional prevention measures are warranted.
  • Understanding previous land use can help farms identify and address potential sources of pathogens that may affect their farming operations.  
  • Be cognizant of and assess risks that may be posed by adjacent and nearby land uses, especially as it relates to the presence of livestock, including poultry, and the interface between farmland, and other agricultural areas.
  • Consider additional tools such as pre-harvest and/or post-harvest sampling and testing of products to help inform the need for specific prevention measures.
  • Poultry manure, while valued for its fertilizer value, is a known reservoir for Salmonella spp.  Proper application of a manure that has been treated with a validated and verified process to reduce pathogens (e.g. composting with time and temperature measurements) can significantly reduce the potential for the integration of Salmonella or other human pathogens into soils (as compared to the use of raw manures).
  • Inspect, maintain, and clean and, when necessary and appropriate, sanitize all food contact surfaces of equipment and tools used as frequently as reasonably necessary to protect against contamination.
  • When appropriate, use EPA-approved products according to the label for cleaning and sanitizing.
  • Inconsistent adherence to or deviation from existing SOPs for cleaning and sanitizing by farms can affect produce safety. Effective communication on farms about SOPs and any changes to those SOPs can help ensure that food safety practices are being followed.
  • Root cause analyses may be useful in identifying for growers how human pathogen sources in the broader agricultural environment may contribute to contamination.
  • Improve traceability through increased digitization, interoperability, and standardization of traceability records which would expedite traceback and help remove contaminated product from the marketplace more quickly, thereby preventing further illnesses. This is not only important for growers, but also critical for shippers, manufactures, and retailers as well, to improve overall traceability throughout the supply chain.

FDA will work in conjunction with the Indiana State Department of Health to increase awareness amongst the melon growing industry of pathogenic environmental strains in the region to develop and promote risk reduction strategies related to melon growing and harvesting to minimize the impact of these strains.

Food safety is a shared responsibility that involves food producers, distributors, manufacturers, retailers, and regulators. Recognizing the interconnection between people, animals, plants, and their shared environment when it comes to public health outcomes, we encourage collaboration among various groups in the broader agricultural community (i.e., produce growers, state government and academia) to address this issue. Over a decade ago I penned a post entitled “Towards a Policy of Secrecy or Transparency in Public Health.” Here is a bit of it:

A.  Although there is no written policy, it is the way we have done things for years;

Why do I hear my mom saying, “just because so and so does that does not mean you should too.” Like all government policies (and neckwear) – change is good.

B.  Since the outbreak has concluded, there is not an immediate public health threat.

Frankly, that is true in most foodborne illness outbreaks.  In nearly every single outbreak investigated by the CDC the outbreak is figured out far after the peak of the illnesses happened.  However, disclosure gives the public information on which companies have a strong or weak food safety record.

C.  Disclosing the name of the company jeopardizes cooperation from the company in this and future outbreaks; and

If a company will only cooperate if they are placed in a witness protection program and with promises of non-disclosure, it does not say much for our governments and the company’s commitment to safe food.

D.  Bad publicity may cause economic hardship on the restaurant.

True, but not poisoning your customers is a better business practice.

I would also add a couple more reasons that I have received via email (mostly anonymously):

1.  The source was an unknown supplier, so naming the restaurant might place unfair blame on the restaurant.

This one does make some sense.  However, is this the unnamed restaurants first problem with a faulty supplier, or is this a pattern?  And, even if it is the first time, perhaps some of the unnamed product is still in the market? 

2.  Since the outbreak involves a perishable item, by the time the CDC announces the outbreak, the tainted product has long been consumed.

This one I have heard a “bunch” of times – especially in leafy green outbreaks.  However, why should the public be left in the dark about the type of product that sickens as well as the likely grower and shipper so they can make future decision who to buy from?

3.  Going public with the name of the restaurant compromises the epidemiologic investigation by suggesting the source of the outbreak before the investigation is complete.

I completely agree with this one.  This is a tough call, and one that must create the most angst for public health officials – they decide the balance between having enough data to go forward to protect the public health or wait for more data.  The point is do not go forward until the investigation is complete.

4.  Public health is concerned of making an investigation mistake like, it’s the tomatoes, err, I mean peppers; and

See my answer to 3 above.  This is why under the law; public health officials are immune for liability for the decisions that they make in good faith to protect the public.

5.  Public health – especially surveillance – is under budgetary pressures and there is simply not the resources to complete investigations; and

There is no question that this is true.  I have seen it in dropped investigations over the last few years.  Labs are not doing genetic fingerprinting to help reveal links between ill people.  And many tracebacks are stopped by the lack of peoplepower to do the research necessary to find the “root cause” of an outbreak.

For me it is easy – the public has a right to know and to use the information as it sees fit, and people – especially government employees – have no right to decide what we should and should not know.