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18 Jul 2013

Foodborne Outbreak of Group A Streptococcus Pharyngitis Associated With a High School Dance Team Banquet—Minnesota, 2012 (Clin Infect Dis., abstract, edited)

[Source: Clinical Infectious Diseases, full page: (LINK). Abstract, edited.]

Foodborne Outbreak of Group A Streptococcus Pharyngitis Associated With a High School Dance Team Banquet—Minnesota, 2012

Sarah K. Kemble 1,4, Amy Westbrook 1, Ruth Lynfield 1, April Bogard 1, Nicole Koktavy 1, Kelly Gall 2, Victoria Lappi 2, Aaron S. DeVries 1, Edward Kaplan 3, and Kirk E. Smith 1

Author Affiliations: 1Minnesota Department of Health 2Minnesota Department of Health Public Health Laboratory, Saint Paul 3Department of Pediatrics, University of Minnesota Medical School, Minneapolis 4Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, Georgia

Correspondence: Sarah K. Kemble, MD, Rush University Medical Center, Division of Infectious Diseases, 600 South Paulina St, Ste 140, Chicago, IL 60615 (




On 20 March 2012, the Minnesota Department of Health (MDH) was notified of multiple Facebook postings suggestive of a foodborne outbreak of Group A Streptococcus (GAS) pharyngitis occurring among attendees of a high school dance team banquet. An investigation was initiated.


Associations between GAS pharyngitis and specific food items were assessed among banquet attendees. Pharyngeal swabs were performed on attendees, household contacts, and food workers. Patient GAS isolates from clinical laboratories were also obtained. Pharyngeal and food specimens were cultured for GAS by the MDH Public Health Laboratory. Isolates were further characterized by pulsed-field gel electrophoresis (PFGE) and emm typing.


Among 63 persons who consumed banquet food, 18 primary illnesses occurred, yielding an attack rate of 29%. Although no food or beverage items were significantly associated with illness, pasta consumption yielded the highest relative risk (risk ratio, 3.56; 95% confidence interval, .25–50.6). GAS colonies with indistinguishable PFGE patterns corresponding to emm subtype 1.0 were isolated from 5 patients and from leftover pasta. The pasta was prepared at home by a dance team member parent; both parent and child reported GAS pharyngitis episodes 3 weeks before the banquet.


In this foodborne outbreak of GAS pharyngitis, pasta was implicated as the vehicle. Recognition of foodborne GAS illness is challenging because transmission is typically assumed to occur by respiratory spread; foodborne transmission should be considered when clusters of GAS pharyngitis patients are encountered. DNA-based typing can reveal potentially epidemiologically related isolates during GAS disease outbreaks and facilitate understanding and control of GAS disease.

Key words: Streptococcus pyogenes – pharyngitis - foodborne diseases - pulsed-field gel electrophoresis - social media

Received February 19, 2013. Accepted May 17, 2013.

Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2013.