Shiga toxin-producing Escherichia coli O157:H7 outbreak associated with school field trips at a farm animal exhibit-Tennessee, September-October 2023.

AIMS: In October 2023, the Tennessee Department of Health identified an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 infections among elementary school students who attended school field trips to the same farm animal exhibit. Our aim was to determine STEC source and prevent additional illnesses by initiating epidemiologic, laboratory and environmental investigations. METHODS AND RESULTS: We identified cases using laboratory-based surveillance and by surveying caregivers of children who attended the exhibit. Probable cases were defined as illness with abdominal cramps or diarrhoea 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 faeces and environmental samples were tested for STEC O157:H7 by real-time polymerase chain reaction (PCR), culture and whole-genome sequencing (WGS). Approximately 2300 elementary school students attended the animal exhibit during 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 from 399 caregivers for 443 (19%) animal exhibit attendees. We identified 9 confirmed and 55 probable cases with illness onset dates during 26 September to 12 October. Seven children aged 1-7 years were hospitalized. Four children aged 1-6 years experienced haemolytic uraemic syndrome; none died. Laboratory testing identified STEC O157:H7 by culture from eight human stool samples with 0-1 allele difference by WGS. Three environmental samples had Shiga toxin (stx 2) genes detected by PCR, but no STEC isolates were recovered by culture. 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.

Multistate outbreak of Salmonella Mbandaka infections linked to sweetened puffed wheat cereal - United States, 2018.

In May of 2018, PulseNet, the national molecular subtyping network for enteric pathogens, detected a multistate cluster of illnesses caused by an uncommon molecular subtype of Salmonella serovar Mbandaka. A case was defined as an illness in a person infected with the outbreak strain of Salmonella Mbandaka with illness onset on or after 3 March 2018 and before 1 September 2018. One-hundred thirty-six cases from 36 states were identified; 35 hospitalisations and no deaths were reported. Ill people ranged in age from <1 year to 95 years (median: 57 years). When standardised questionnaires did not generate a strong hypothesis, opened-ended interviews were performed. Sixty-three of 84 (75%) ultimately reported consuming or possibly consuming a specific sweetened puffed wheat cereal in the week before illness onset. Environmental sampling performed at the cereal manufacturing facility yielded the outbreak strain. The outbreak strain was also isolated from open cereal samples from ill people's homes and from a sealed retail sample. Due to these findings, the brand owner of the product issued a voluntary recall of the cereal on 14 June 2018. Additional investigation of the manufacturing facility identified persistent environmental contamination with Salmonella Mbandaka that was closely genetically related to other isolates in the outbreak. This investigation highlights the ability of Salmonella to survive in low-moisture environments, and the potential for prolonged outbreaks linked to products with long shelf lives and large distribution areas.

Phylogenetic Analysis Reveals Source Attribution Patterns for Campylobacter spp. in Tennessee and Pennsylvania.

Campylobacteriosis is the most common bacterial foodborne illness in the United States and is frequently associated with foods of animal origin. The goals of this study were to compare clinical and non-clinical Campylobacter populations from Tennessee (TN) and Pennsylvania (PA), use phylogenetic relatedness to assess source attribution patterns, and identify potential outbreak clusters. Campylobacter isolates studied (n = 3080) included TN clinical isolates collected and sequenced for routine surveillance, PA clinical isolates collected from patients at the University of Pennsylvania Health System facilities, and non-clinical isolates from both states for which sequencing reads were available on NCBI. Phylogenetic analyses were conducted to categorize isolates into species groups and determine the population structure of each species. Most isolates were C. jejuni (n = 2132, 69.2%) and C. coli (n = 921, 29.9%), while the remaining were C. lari (0.4%), C. upsaliensis (0.3%), and C. fetus (0.1%). The C. jejuni group consisted of three clades; most non-clinical isolates were of poultry (62.7%) or cattle (35.8%) origin, and 59.7 and 16.5% of clinical isolates were in subclades associated with poultry or cattle, respectively. The C. coli isolates grouped into two clades; most non-clinical isolates were from poultry (61.2%) or swine (29.0%) sources, and 74.5, 9.2, and 6.1% of clinical isolates were in subclades associated with poultry, cattle, or swine, respectively. Based on genomic similarity, we identified 42 C. jejuni and one C. coli potential outbreak clusters. The C. jejuni clusters contained 188 clinical isolates, 19.6% of the total C. jejuni clinical isolates, suggesting that a larger proportion of campylobacteriosis may be associated with outbreaks than previously determined.

Disparities in Shigellosis Incidence by Census Tract Poverty, Crowding, and Race/Ethnicity in the United States, FoodNet, 2004-2014.

BACKGROUND: Shigella causes an estimated 500 000 enteric illnesses in the United States annually, but the association with socioeconomic factors is unclear. METHODS: We examined possible epidemiologic associations between shigellosis and poverty using 2004-2014 Foodborne Diseases Active Surveillance Network (FoodNet) data. Shigella cases (n = 21 246) were geocoded, linked to Census tract data from the American Community Survey, and categorized into 4 poverty and 4 crowding strata. For each stratum, we calculated incidence by sex, age, race/ethnicity, and FoodNet site. Using negative binomial regression, we estimated incidence rate ratios (IRRs) comparing the highest to lowest stratum. RESULTS: Annual FoodNet Shigella incidence per 100 000 population was higher among children <5 years old (19.0), blacks (7.2), and Hispanics (5.6) and was associated with Census tract poverty (incidence rate ratio [IRR], 3.6; 95% confidence interval [CI], 3.5-3.8) and household crowding (IRR, 1.8; 95% CI, 1.7-1.9). The association with poverty was strongest among children and persisted regardless of sex, race/ethnicity, or geographic location. After controlling for demographic variables, the association between shigellosis and poverty remained significant (IRR, 2.3; 95% CI, 2.0-2.6). CONCLUSIONS: In the United States, Shigella infections are epidemiologically associated with poverty, and increased incidence rates are observed among young children, blacks, and Hispanics.

Mumps Outbreaks at Four Universities - Indiana, 2016.

From February to April 2016, the Indiana State Department of Health (ISDH) confirmed mumps outbreaks at four universities (three public and one private). All universities were located within 65 miles of Indianapolis; however, epidemiologic links among outbreaks were limited. ISDH and local health departments investigated the outbreaks and initiated control measures at all universities. A protocol describing recommended testing for mumps, testing priorities during the outbreak, and a preauthorization process for submitting specimens to the ISDH Laboratory (ISDHL) was developed and disseminated to providers and public health partners (1). Outbreaks at each university were declared over after two incubation periods* elapsed without identified cases; the last outbreak ended September 10, 2016. Among the 281 confirmed and probable cases identified, 216 (76.9%) persons had documentation of presumptive evidence of immunity† (2). At some universities, documentation of receipt of 2 doses of measles, mumps, rubella vaccine (MMR), which is a criterion for evidence of immunity, was not available and required substantial personnel time to verify. Implementation of policies for excluding susceptible persons from classes and other group settings was also difficult. The laboratory testing protocol increased the percentage of specimens testing positive and improved case detection. Outbreak-specific laboratory testing guidance on specimen collection for mumps confirmation and standardized vaccination documentation in highly vaccinated settings could aid outbreak management. Evaluation of exclusion policies might also be necessary. In 2018, the Advisory Committee on Immunization Practices (ACIP) published a recommendation that persons previously vaccinated with 2 doses of MMR who are determined by public health authorities to be part of a group at increased risk for infection during a mumps outbreak receive a third dose of MMR (3).

Immunization documentation practices and vaccine-preventable disease surveillance capacity among institutions of higher education in Indiana.

OBJECTIVE: Complete and accurate documentation of immunization records and surveillance of disease transmission are critical to the public health response to outbreaks of communicable disease in institutions of higher education (IHEs). This study aims to describe immunization documentation practices and disease surveillance capacity among IHEs in Indiana in order to inform public health action. METHODS: IHEs in Indiana were identified and included in the study if they offered on-campus housing and had a dedicated student health center. Phone surveys were administered in September 2015 to each institution, inquiring about current immunization documentation policies and practices, disease surveillance capacity, and use of statewide electronic reporting systems. Additionally, IHE websites were searched to identify immunization documentation requirements for matriculating students. RESULTS: Surveys were completed for 33 of 38 eligible IHEs. Twenty-three (70%) IHEs reported that student immunization records are entered into an accessible electronic system or database. Matriculating student immunization requirements were identified for 32 institutions. Of these, 22 (69%) required a physician-signed proof of immunization. No IHEs reported documenting historical immunizations in the statewide electronic immunization system and three IHEs (9%) reported utilizing the state electronic disease surveillance program. CONCLUSIONS: Immunization documentation practices vary among IHEs in Indiana and use of statewide immunization and disease reporting systems is minimal. Robust utilization of immunization and disease surveillance systems has been shown to improve public health response to communicable disease outbreaks. Improving mutual understanding of policy and practice between health departments and IHEs could improve the ability to respond to public health challenges.