Those nerds at the FDA and CDC have been at it again, thank goodness.
They took a crazy close look at the Listeria outbreak traced to Blue Bell Creameries ice cream and found evidence supporting the long-held assumption that very small amounts of the pathogen can lead to serious infections in some groups of people.
Though they didn’t name the iconic company, as is the practice for many of the reports that come out of the Centers for Disease Control and Prevention, the details of the outbreak spoke for themselves.
If the report ever makes it to the Jeopardy board, it will be easy for Alex Trebek to pose the question: “What listeriosis outbreak involved ice cream, spanned five years and included five victims at one Kansas hospital?”
The research report discusses the “dose-response relationship” between pathogens and human bodies, which can be difficult to determine because foods implicated in outbreaks are usually exposed to conditions that encourage pathogen growth.
“Understanding the likelihood of developing invasive listeriosis after ingesting a given number of Listeria monocytogenes cells — dose-response relationship — is important in managing risks linked to this pathogen in food,” the researchers reported.
With ice cream and Listeria, the product and pathogen are generally kept at below-freezing temperatures until consumption, giving the researchers a leg up on the dose-response relationship.
“This outbreak provided a unique opportunity to assess exposure levels to L. monocytogenes from implicated ice cream products among infected persons and the overall population,” according to the research report, published in the Journal Emerging Infectious Diseases.
“Because ice cream has a long shelf life and L. monocytogenes does not grow but survives for long periods in frozen products, the level of L. monocytogenes in implicated products manufactured during the outbreak, although collected after the outbreak, was likely to be representative of levels in products eaten by exposed persons.”
Based on information from the hospital in Kansas, the researchers calculated the outbreak victims there received about 80 grams, or 2.8 ounces, of ice cream per serving. For the three patients with information available, the victims consumed two or three servings over periods ranging from two to nine days.
“… the mean contamination level of L. monocytogenes in the milkshakes — 8 cells per gram of ice cream — was relatively low compared with contamination levels in some other outbreaks,” the researchers reported.
“Despite the relatively low levels of contamination of ice cream products in this listeriosis outbreak, the exceptionally high prevalence of contaminated products, combined with the protracted duration of contamination of the production line — at least one year and possibly longer — contributed to exposure of many persons to L. monocytogenes.”
That large pool of exposed people suggests low levels of Listeria contamination in products that don’t support growth of the pathogen probably means only a limited number of people — the very old, the very young, the very sick — will be come infected, according to the report.
Great news everybody, if you’re a healthy adult you’re less likely to get sick
On the flip side, if your immune system is compromised or not yet fully developed and you encounter Listeria, a little dab’ll do ya. Do you in, that is.
“This outbreak of ice cream-associated listeriosis recognized in 2015 demonstrates that illnesses can occur when products with low-level contamination that do not support growth are distributed widely to the public,” according to the research report.
“Finally, this outbreak adds yet further evidence of the risk for listeriosis faced by persons with weakened immune systems and calls for effective risk management to mitigate infections.”
So for all of those out there who are in pathogen denial, for those who claim that they ate bugs and dirt as children and never got sick, for those who say people today are a germ-a-phobic bunch of wimps, here’s hoping you get your milk shakes on schedule next time you’re in an intensive care unit.
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