Shiga toxin-producing escherichia coli O157:H7 outbreak associated with school field trips at a “farm days” animal exhibit—Tennessee, September–October 2023

Authors: THOMAS, CHRISTINE - Centers For Disease Control And Prevention (CDC) - United States; FOSTER, ALLISON - Tennessee Department Of Health; KIRSCHKE, DAVID - Tennessee Department Of Health; MOONEY, HOPELYN - Tennessee Department Of Health; REID, ISABELLA - Tennessee Department Of Health; MAY, ANDEREW - Sullivan County Regional Health Department; MULLINS, HEATHER - Sullivan County Regional Health Department; FILL, MARY-MARGARET - Tennessee Department Of Health; GARMAN, KATIE - Tennessee Department Of Health; GOLWALKAR, MUGDHA - Tennessee Department Of Health; JONES, TIMOTHY - Tennessee Department Of Health; MARR, JACK - Tennessee Department Of Health; OREJUELA, KELLY - Tennessee Department Of Health; RIPLEY, DANNY - Tennessee Department Of Health; RASNIC, ROBIN - Tennessee Department Of Health; TERRELL, ERICA - Tennessee Department Of Health; SCHAFFNER, WILLIAM - Vanderbilt University Medical Center; Durso, Lisa; DUNN, JOHN - Tennessee Department Of Health

Submitted to: Zoonoses and Public Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2024
Publication Date: 11/1/2024
Citation: Thomas, C.M., Foster, A., Kirschke, D., Mooney, H., Reid, I., May, A.S., Mullins, H., Fill, M.A., Garman, K.N., Golwalkar, M., Jones, T.F., Marr, J.H., Orejuela, K., Ripley, D., Rasnic, R., Terrell, E., Schaffner, W., Durso, L.M., Dunn, J.R. 2024. Shiga toxin-producing escherichia coli O157:H7 outbreak associated with school field trips at a “farm days” animal exhibit—Tennessee, September–October 2023. Zoonoses and Public Health. 71(7):829-835. https://doi.org/10.1111/zph.13161.
DOI: https://doi.org/10.1111/zph.13161

Interpretive Summary: This manuscript reports the result of and outbreak of Shiga-toxigenic E. coli O157:H7 among elementary school students attending a school field trip to a farm. Health Department officials led a collaborative team to investigate the source of the outbreak. This is the largest reported STEC O157:H7 outbreak associated with an animal exhibit in Tennessee. We identified opportunities for educating school staff, event organizers, and families about zoonotic disease risks associated with animal contact and published prevention measures.

Technical Abstract: Background: In October 2023, the Tennessee Department of Health identified an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 infections among elementary students who attended school “Farm Days” field trips to the same animal exhibit. To determine STEC source and prevent additional illnesses, we initiated epidemiologic, laboratory, and environmental investigations. Methods: We identified cases using laboratory-based surveillance and by surveying parents and guardians of children who attended the exhibit. Probable cases were defined as illness with abdominal cramps or diarrhea after attendance; confirmed cases were laboratory-confirmed STEC infection in an attendee or household contact. A site visit was conducted and event organizers were interviewed. Human stool, animal feces, and environmental samples were tested for STEC O157:H7 by polymerase chain reaction (PCR), culture, and whole genome sequencing (WGS). Results: Approximately 2,300 elementary school students attended the animal exhibit over 2 days. Field trip activities included contact with different farm animal species, drinking pasteurized milk outside animal enclosures, and eating lunch in a separate building onsite. We received survey responses for 443 (19%) persons. We identified 9 confirmed and 55 probable cases with illness onset dates during September 26–October 12. Seven children aged 1–7 years were hospitalized. Four children aged 1–6 years developed hemolytic uremic syndrome; none died. Laboratory testing identified STEC O157:H7 by culture from 8 human stool samples with 0–1 allele difference by WGS. Three environmental samples had Shiga toxin detected by PCR; culture did not identify STEC isolates. Three other environmental samples had E. coli O157:H7 culture isolates that were genetically distinct from the human isolates. Conclusions: This is the largest reported STEC O157:H7 outbreak associated with an animal exhibit in Tennessee. We identified opportunities for educating school staff, event organizers, and families about zoonotic disease risks associated with animal contact and published prevention measures.