Salmonella Outbreak Grows. Cantaloupes Recalled

The number of people infected with Salmonella Typhimurium in the USA’s most recent produce-related outbreak has increased to 178, according to data released this morning by CDC. Sixty-two people have been hospitalized. The death toll remains at two – both of them from Kentucky.

Twenty-one states have reported at least one illness – up from the previous total of twenty. Salmonella Typhimurium infections due to the outbreak strain were documented in Alabama (13), Arkansas (3), California (2), Georgia (3), Illinois (21), Indiana (18), Iowa (7), Kentucky (56), Massachusetts (2), Michigan (6), Minnesota (4), Mississippi (5), Missouri (12), New Jersey (2), North Carolina (3), Ohio (4), Pennsylvania (2), South Carolina (3), Tennessee (6), Texas (2), and Wisconsin (4).

Salmonella Typhimurium outbreak. Cases reported by state (from CDC)

Investigations by CDC, FDA and local and state agencies have concluded that cantaloupe originating from Chamberlain Farm Produce, Inc. of Owensville, Indiana is a likely source of this outbreak. Late yesterday, Chamberlain Farm Produce, Inc. announced a voluntary recall of all of its cantaloupes from the 2012 growing season that may remain in the marketplace. This follows a prior market withdrawal of cantaloupes initiated by Chamberlain on August 16th and 17th.

Chamberlain’s cantaloupes were marketed to four retail grocery stores with outlets in Vanderburgh, Warrick, Gibson, and Dubois County, Indiana, and Wabash County, Illinois during the period of June 21, 2012 to August 16, 2012; four wholesale purchasers in Owensboro, Kentucky, St. Louis, Missouri, Peru, Illinois, and Durant, Iowa also procured cantaloupes from Chamberlain during that same period. According to FDA, the cantaloupes were initially shipped to Indiana, Kentucky, Missouri, Tennessee, Ohio, Illinois, and Wisconsin, with further distribution likely.

Although the names of the retail and wholesale consignees have not been released, Wal-Mart has been named as the source of cantaloupes consumed by two outbreak victims from one family in Michigan, and by one of the Mississippi outbreak victims.

While FDA and CDC have identified “a source” of this outbreak, the investigation is continuing in order to determine whether there are other possible sources. The outbreak strain of Salmonella Typhimurium is a common one, and is typically the source of 10 to 15 “background” cases each month across the USA. Only 75% of the outbreak victims interviewed during the initial investigation reported having consumed cantaloupe before becoming ill.

Updated CDC Advice to Consumers, Retailers, and Others

Contaminated cantaloupe may still be in grocery stores and in consumers’ homes.

Consumers who recently purchased Chamberlain Farms cantaloupes are advised not to eat them and discard any remaining cantaloupe.
- Based on the available information, consumers can continue to purchase and eat cantaloupes that did not originate from Chamberlain Farms Produce, Inc.
- Many cantaloupes have the growing area identified with a sticker on the fruit. If no sticker is present, consumers should inquire about the source. When in doubt, throw it out.
- Consumers who are buying or have recently bought cantaloupe should ask their retailer if the cantaloupe originated from Chamberlain Farms Produce, Inc.
Cantaloupes should be disposed of in a closed plastic bag placed in a sealed trash can. This will prevent people or animals from eating them.
Dispose of any cantaloupes that you think may be contaminated. Washing them will not completely eliminate the contamination. Cutting, slicing and dicing may also transfer harmful bacteria from the fruit’s surface to the fruit’s flesh.
Retailers and food service operators should not sell or serve Chamberlain Farms cantaloupe.
Persons who think they might have become ill from eating possibly contaminated cantaloupes should consult their health care providers.

Salmonella Victim Bought Cantaloupe at Wal-Mart

Two Mississippi residents are among the 141 victims of this year’s cantaloupe-linked Salmonella Typhimurium outbreak. Only one of the Mississippians reported having consumed cantaloupe prior to becoming ill, according to Jim Newkirk of the Mississippi State Department of Health’s Office of Communications.

And that person purchased whole cantaloupe from Wal-Mart.

Bloomberg news reported on August 18th that Wal-Mart had withdrawn Indiana cantaloupes from its stores.

Neither of the two Mississippi outbreak victims was hospitalized, and no additional cases are currently under investigation in that state. The confirmed cases were reported from Rankin and Itawamba counties. Rankin County is east of Jackson, in the center of the state; Itawamba County is in Mississippi’s northeast corner.

As of August 17th, CDC reported that 141 outbreak cases of Salmonella Typhimurium had been documented in 20 US states. The agency expects to update those numbers later this week, according to CDC spokesperson Lola Russell.

While all of the 141 outbreak victims were infected with the same strain of Salmonella Typhimurium, only 75% (18 of 24) of those interviewed reported having consumed cantaloupe before becoming ill. Neither California victim was exposed to cantaloupe – or to other melons – and neither travelled to the hardest hit states (Kentucky, Indiana, Illinois). Only two of Iowa’s seven outbreak victims ate cantaloupe.

Ronald Owens of the California Department of Public Health offered this explanation when contacted by eFoodAlert:

It is not uncommon in these outbreak investigations to occasionally identify people who were infected by a similar strain of bacteria to the outbreak strain but who are considered “background” cases that are not related to an outbreak. The U.S. Centers for Disease Control and Prevention (CDC) estimates that there are about 10-15 background cases with this particular strain pattern that are detected each month.

This illustrates the difficulty faced by epidemiologists and public health officials in detecting and defining a foodborne disease outbreak that is caused by a relatively common genetic strain of bacteria. It’s far easier to recognize a needle in a haystack than to distinguish between two pieces of hay. In these circumstances, CDC defines an outbreak case as one that is a genetic match to the outbreak strain and falls within the outbreak timeframe.

Neither CDC nor FDA is yet prepared to identify the southwestern Indiana farm that is believed to be the source of the contaminated cantaloupes. No public recall has been announced.

CDC’s Advice to Consumers, Retailers and Others (as of August 17, 2012)

Contaminated cantaloupe may still be in grocery stores and in consumers’ homes.

Consumers who recently purchased cantaloupes grown in southwestern Indiana are advised not to eat them and discard any remaining cantaloupe.
- Based on the available information, consumers can continue to purchase and eat cantaloupes that did not originate in southwestern Indiana.
- Many cantaloupes have the growing area identified with a sticker on the fruit. If no sticker is present, consumers should inquire about the source. When in doubt, throw it out.
- Consumers who are buying or have recently bought cantaloupe should ask their retailer if the cantaloupe was grown in southwestern Indiana.
Cantaloupes should be disposed of in a closed plastic bag placed in a sealed trash can. This will prevent people or animals from eating them.
Dispose of any cantaloupes that you think may be contaminated. Washing them will not completely eliminate the contamination. Cutting, slicing and dicing may also transfer harmful bacteria from the fruit’s surface to the fruit’s flesh.
Retailers and food service operators should not sell or serve cantaloupe from southwestern Indiana.
Persons who think they might have become ill from eating possibly contaminated cantaloupes should consult their health care providers.

An Open Letter To The U.S. CDC

Last week, CDC released two “Final Update” reports on Salmonella outbreak investigations within a 48-hour period.

The first report, released on January 17th, summarized the results of an investigation into a 10-month long outbreak of Salmonella Typhimurium associated with exposure to clinical and teaching microbiology laboratories. The second report, released on January 19th, presented the results of an investigation into a 2-month long multi-state outbreak of Salmonella Enteritidis infections linked to a restaurant chain.

These two outbreaks had very little in common with each other; the outbreak settings were different, the scope and duration of the outbreaks were different, and the source of the infections was different. Nevertheless, the two outbreaks have one very important thing in common.

CDC, in conjunction with at least some of its public health partners at the state and local level, has chosen to withhold important information from the public.

What information has CDC withheld, and why should this information be released? Here is a list of questions that I sent to my media contact at CDC on January 18th, the day after the Salmonella Typhimurium outbreak report was released.

Is there a specific reason why CDC is not specifying the identity of the commercial strain of Salmonella Typhimurium that is associated with this outbreak (by the ATCC or NCTC strain number – not the commercial supplier)? Can you provide me with the strain number ID?
Does CDC have any hypothesis as to the trigger for this outbreak? Most of the commercial strains have been in use in various labs for many years. What may have happened to initiate the increase in cases? What determined the start date? With a baseline rate for the outbreak strain of 0 to 4 reports/week, how were the start and ending date established for this outbreak?
Were the outbreak cases all tied to the same commercial source of the S. Typhimurium “Strain X”?
Were the outbreak cases tied to the use of a specific format of the commercial source (for example, Bacti-discs or pre-filled inoculation loops)?
Have any cases involving this same strain been reported to CDC since the last “outbreak” case on June 29, 2011? If so, how has CDC differentiated those cases from the outbreak cases (keeping in mind the baseline of 0-4 cases per week mentioned in the CDC report).
Were the bulk of the cases linked to student labs or to clinical labs?

To these questions, I would now add, “Were the clinical lab cases tied mainly to in-hospital labs, or to free-standing commercial clinical labs? If the latter, was any single commercial lab chain disproportionately involved?”

When the Salmonella Enteritidis restaurant chain outbreak report hit the internet, I again contacted my CDC media liaison and asked, “Can you please explain why CDC has not revealed the name of the restaurant chain implicated in the above-mentioned outbreak? Even better, can you identify the chain by name?”

I realize that both outbreaks are “over” and that at least some of this information now is academic. Nevertheless, I question CDC’s actions in withholding information that could influence purchasing decisions on the part of consumers and of medical and lab professionals.

CDC reported on January 19th that Restaurant Chain A’s handling and cooking processes likely ruled out ground beef as a source of the Salmonella Enteritidis outbreak. This is favorable to the restaurant chain, and would give consumers comfort that the restaurants belonging to this fast food chain are following appropriate food-handling procedures – if only CDC had released the name of the chain.

As for the lab-related outbreak, if I was still running a microbiology lab, I would certainly want to know whether a specific packaging or format of commercially available control culture was more prone to contaminating the lab surroundings than others. I would opt to avoid this format, if I had the information and the choice. Likewise, as a medical doctor, I would opt to avoid a commercial clinical lab chain that was prone to in-lab contamination.

If either of these outbreaks had been traced to a specific packaged food, the offending food would have been named. There is no logical reason for restaurant-linked outbreaks to be handled differently. There is no logical reason for a lab-related outbreak to be handled differently.

I would appreciate receiving substantive answers to my questions.

Sincerely yours,

Phyllis Entis, MSc., SM(NRCM)
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