Abstract
During September 2019, public health authorities in El Paso County, Colorado, were notified of four patients who had presented to nearby hospitals with clinical features consistent with botulism, a paralytic illness caused by botulinum neurotoxin. One patient died soon after presentation; the other three patients required intensive care but recovered after receiving botulism antitoxin. Botulinum toxin type A was detected in serum from all patients. On further investigation, all four patients had shared a meal that included commercially prepared roasted potatoes from an individual package without refrigeration instructions that had been left unrefrigerated for 15 d. Storage of the product at ambient temperature likely allowed botulism spores to produce botulinum toxin, resulting in severe illness and death. The manufacturer improved labeling in response to this outbreak. Public health officials should consider unrefrigerated potato products as a potential source of botulism; clinicians should consider botulism as a possible cause of paralytic illness.
On September 21, 2019, clinicians notified El Paso County Public Health (EPCPH) and Colorado Department of Public Health and Environment (CDPHE) of three patients with suspected foodborne botulism, a paralytic illness caused by toxin from Clostridium botulinum (Rao et al, 2017). CDPHE contacted the Centers for Disease Control and Prevention (CDC) to request clinical consultation, testing, and antitoxin.
All patients had symptoms consistent with botulism, including ptosis, diplopia, blurred vision, dysphagia, subjective weakness, and descending paralysis (Centers for Disease Control and Prevention, 1998). An 80-year-old woman became ill on September 18, developed respiratory failure, and died on September 20; she was not intubated due to a pre-existing nonresuscitation order. The other patients were her 58-year-old son and 55-year-old daughter; they developed symptoms on September 19 and presented to two different hospitals. On September 22, EPCPH and CDPHE were notified of a fourth patient who presented to a third hospital, a 58-year-old family friend who became ill on September 20.
Within the 24 h of public health notification, the three surviving patients received antitoxin while in an intensive care unit; two required intubation. Botulinum toxin type A was detected in serum from all patients using mass spectrometry, and in C. botulinum isolated from stool of the surviving patients (Centers for Disease Control and Prevention, 1998; Kalb et al, 2012).
To investigate further, EPCPH conducted interviews with ∼15 people including the surviving patients, household contacts, relatives, and friends. EPCPH made a visit to the family's home during a concurrent law enforcement investigation of the initially unexplained death. At the time of the investigation, eight members of this multigenerational family resided in the home. All patients had shared a meal on September 17 that included roasted potatoes from a sealed, preservative-free, and ready-to-eat package. Patients reported eating very little of the potatoes and discarding them because they tasted “foul.” No other persons were present for the meal or consumed the potatoes, and no other household contacts had symptoms of botulism. No food from the meal was available for testing.
A family member purchased the product from a national retailer on September 3, 2019, as a refrigerated double pack, and consumed the first package the following day without adverse effects. The second package was stored unrefrigerated for 15 d before being warmed in a microwave by the patients. Examination of another package of the same product revealed that the external sleeve was marked “Keep Refrigerated” in letters 6.35 mm tall; individual packages had no refrigeration instructions.
Conclusions
This outbreak of foodborne botulism was caused by consuming a commercially produced roasted potato product that was not properly refrigerated. C. botulinum spores were likely present on the potatoes and survived roasting; C. botulinum spores are heat resistant and can survive high temperatures allowing them to persist in the product during roasting (Angulo et al, 1998; Centers for Disease Control and Prevention, 1998). Storage of the second package at ambient temperature for 15 d likely allowed botulism spores to germinate and produce botulinum toxin, resulting in one death and three admissions to intensive care.
Development of botulism in everyone who consumed the meal suggests contamination throughout the product. C. botulinum spores can be found in soil and in a variety of foods, but require favorable conditions to produce toxin, including temperature ≥3°C (>10°C for strains producing type A toxin), an anaerobic environment, and pH >4.6 (Peck, 2010). Although the manufacturer described the film sealing the packages as semipermeable, this environment still allowed botulism spores to produce toxin.
Investigations of some previous outbreaks have attributed illness to toxin production in commercial products left at ambient temperature, sometimes despite refrigeration instructions (Angulo et al, 1998; Kalluri et al, 2003; Peck, 2006; Seaman et al, 2011; Sheth et al, 2008). This investigation was challenging because the patients were admitted to three different hospitals, it was not possible to communicate with patients who were intubated, and investigation of an initially unexplained death occurred concurrently, requiring careful coordination with social services and other community members.
In response to this outbreak, CDPHE recommended that the manufacturer enlarge the refrigeration instructions on the external sleeve, add refrigeration instructions to individual packages, and explore techniques to prevent toxin production if unrefrigerated. The manufacturer improved product labeling in 2020 but was not able to modify the processing techniques to prevent toxin production. When investigating possible food sources for patients with botulism, public health professionals should consider inadequately refrigerated commercial products that contain potatoes in addition to home-canned vegetables, low-acid foods, and insufficiently preserved fish or meat (Kalb et al, 2012).
Clinicians should contact their state health department for advice on antitoxin treatment and confirmatory testing for any patient with an illness consistent with botulism, particularly if there was a relevant exposure. For consumers, the risk of foodborne botulism can be reduced by discarding commercially produced potato-containing products that are improperly stored at ambient temperature.
Footnotes
Authors' Contributions
N.G. contributed to conceptualization, investigation, writing—original draft. I.D.P. and R.H.J. were involved in conceptualization, investigation, supervision, writing—original draft. L.E. carried out investigation, supervision, writing—review and editing. M.P. was involved in investigation. R.K.H., R.J., K.P., and J.D. were in charge of conceptualization, investigation, and supervision. G.A.G.: investigation.
Disclosure Statement
No competing financial interests exist.
Funding Information
Some work described in the article was supported by the Epidemiology and Laboratory Capacity for Infectious Disease Cooperative Agreement through the Centers for Disease Control and Prevention (CK19-1904).