Lessons Learned From the Stakeholder Engagement in Research: Application of Spatial Analytical Tools in One Health Problems.

Stakeholder engagement in research is widely advocated as a tool to integrate diverse knowledge and perspectives in the management of health threats while addressing potential conflicts of interest. Although guidelines for stakeholder engagement exist in public health and environmental sciences, the feasibility of actionable decisions based on scientific analyses and the lessons learned from the stakeholder engagement in the process co-creation of knowledge have been rarely discussed in One Health literature and veterinary sciences. Risk maps and risk regionalization using spatiotemporal epidemiological/analytical tools are known to improve risk perception and communication. Risk maps are useful when informing policy and management decisions on quarantine, vaccination, and surveillance intended to prevent or control threats to human, animal, or environmental health interface (i.e., One Health). We hypothesized that researcher-stakeholder engagement throughout the research process could enhance the utility of risk maps; while identifying opportunities to improve data collection, analysis, interpretation, and, ultimately, implementation of scientific/evidence-based management and policy measures. Three case studies were conducted to test this process of co-creation of scientific knowledge, using spatiotemporal epidemiological approaches, all related to One Health problems affecting Minnesota. Our interpretation of the opportunities, challenges, and lessons learned from the process are summarized from both researcher and stakeholder perspectives. By sharing our experience we intend to provide an understanding of the expectations, realizations, and "good practices" we learned through this slow-moving iterative process of co-creation of knowledge. We hope this contribution benefits the planning of future transdisciplinary research related to risk map-based management of One Health problems.

Epidemiologic evaluation of calcium oxalate urolithiasis in dogs in the United States: 2010-2015.

BACKGROUND: Positive health implications of early recognition of calcium oxalate (CaOx) urolithiasis include increased opportunity for nonsurgical removal, early dietary modification to minimize urolith growth, early removal to avoid urinary obstruction, and early recognition of genetic and metabolic diseases before they contribute to additional morbidity. OBJECTIVES: To identify high- and low-risk dog breeds for CaOx uroliths and to determine the relationship of age and sex to the development of CaOx uroliths. ANIMALS: Calcium oxalate urolith submissions between 2010 and 2015. METHODS: A comparative cross-sectional study was conducted to identify high- and low-risk breeds for CaOx uroliths by comparing cases to multiple comparison groups. At-risk breeds were identified if odds ratios were significant (P value <.05) across all comparison groups. RESULTS: Of 258 898 urolith submissions, 124 285 were CaOx. Calcium oxalate was identified in 212 breeds. Twelve breeds were identified as high-risk breeds, and 14 breeds were identified as low-risk breeds. All high-risk breeds were small dog breeds, and all low-risk breeds were medium to large dog breeds. Overall, the mean age ± standard deviation of the first CaOx urolith was 8.4 ± 2.8 years. CONCLUSIONS AND CLINICAL IMPORTANCE: To achieve the health benefits of preclinical evaluation, breeds at high risk for CaOx urolithiasis should be screened at 5 to 6 years of age, which is 2 to 3 years before likely development of clinical urolithiasis.

Comparison of spatiotemporal patterns of historic natural Anthrax outbreaks in Minnesota and Kazakhstan.

Disease spread in populations is a consequence of the interaction between host, pathogen, and environment, i.e. the epidemiological triad. Yet the influences of each triad component may vary dramatically for different settings. Comparison of environmental, demographic, socio-economic, and historical backgrounds may support tailoring site-specific control measures. Because of the long-term survival of Bacillus anthracis, Anthrax is a suitable example for studying the influence of triad components in different endemic settings. We compared the spatiotemporal patterns of historic animal Anthrax records in two endemic areas, located at northern latitudes in the western and eastern hemispheres. Our goal was to compare the spatiotemporal patterns in Anthrax progression, intensity, direction, and recurrence (disease hot spots), in relation to epidemiological factors and potential trigger events. Reported animal cases in Minnesota, USA (n = 289 cases between 1912 and 2014) and Kazakhstan (n = 3,997 cases between 1933 and 2014) were analyzed using the spatiotemporal directionality test and the spatial scan statistic. Over the last century Anthrax occurrence in Minnesota was sporadic whereas Kazakhstan experienced a long-term epidemic. Nevertheless, the seasonality was comparable between sites, with a peak in August. Declining number of cases at both sites was attributed to vaccination and control measures. The spatiotemporal directionality test detected a relative northeastern directionality in disease spread for long-term trends in Minnesota, whereas a southwestern directionality was observed in Kazakhstan. In terms of recurrence, the maximum timespans between cases at the same location were 55 and 60 years for Minnesota and Kazakhstan, respectively. Disease hotspots were recognized in both settings, with spatially overlapping clusters years apart. Distribution of the spatiotemporal cluster radii between study sites supported suggestion of site-specific control zones. Spatiotemporal patterns of Anthrax occurrence in both endemic regions were attributed to multiple potential trigger events including major river floods, changes in land use, agriculture, and susceptible livestock populations. Results here help to understand the long-term epidemiological dynamics of Anthrax while providing suggestions to the design and implementation of prevention and control programs, in endemic settings.

Effects of Gestation Pens Versus Stalls and Wet Versus Dry Feed on Air Contaminants in Swine Production.

OBJECTIVE: Evolving production practices in the swine industry may alter the working environment. This research characterized the influence of stall versus pen gestation housing and wet versus dry feed in finishing on air contaminant concentrations. METHODS: Eight-hour time-weighted ammonia, hydrogen sulfide, respirable dust, respirable endotoxin, and carbon dioxide concentrations and temperature were measured regularly at stationary locations throughout a year in a facility with parallel gestation stall and open pen housing and parallel finishing rooms using dry and wet feed delivery systems. Hazard indices were calculated using ammonia, hydrogen sulfide, and endotoxin concentrations and relevant occupational exposure limits. Statistical analyses were performed to assess the influence of time of year, housing, and feed on measured parameters. RESULTS: Due to reductions in ventilation rates as outdoor temperatures decreased, season affected pollutant levels more than other factors, with concentrations approximately one order of magnitude greater in winter than during summer. Ammonia, dust, and endotoxin were 25%, 43%, and 67% higher, respectively, on average, in the room with gestation pens than in the room with stalls. Endotoxin concentrations were more than five times higher, on average, with the dry feed system than with wet feed. While individual contaminant concentrations were generally below regulatory limits, hazard index calculations suggest that the effects of combined exposures on respiratory health may present a risk to workers. Elevated levels of respirable endotoxin and hydrogen sulfide were observed during power washing. CONCLUSIONS: Ventilation changes in response to seasonal requirements influenced air contaminant concentrations more than production practices, especially housing type. Wet feed systems substantially reduced airborne endotoxin concentrations.

Longitudinal study of Staphylococcus aureus colonization and infection in a cohort of swine veterinarians in the United States.

BACKGROUND: People working with pigs are at elevated risk of harboring methicillin resistant S. aureus (MRSA) in their nose, which is attributable to occupational exposure to animals harboring livestock adapted S. aureus. To obtain insight into the biological nature of occupationally related nasal culture positivity, we conducted a longitudinal study of 66 swine veterinarians in the USA. METHODS: The study cohort resided in 15 US states and worked predominantly with swine. Monthly for 18 months, participants self-collected nasal swabs and completed a survey to report recent exposure to pigs and other animals; the occurrence of work related injuries; and any relevant health events such as skin and soft tissue infections or confirmed staphylococcal infections. Nasal swabs were cultured using selective methods to determine the presence of MRSA and methicillin susceptible S. aureus (MSSA), and isolates were characterized by spa typing and MLST. RESULTS: Prevalences of S. aureus (64%, monthly range from 58 to 82%) and MRSA (9.5%; monthly range from 6 to15%) were higher than reported for the US population (30% and 1.5% respectively). Predominant spa types were t034 (ST398, 37%), t002 (ST5, 17%) and t337 (ST9/ST398 13%), a distribution similar to that found in a concurrent study in pigs in the USA. Veterinarians were classified into three groups: Persistent carriers (PC, 52%), Intermittent carriers (IC, 47%) and Non-carriers (NC, 1%). Persistent carriage of a single spa type was observed in 14 (21%) of participants, and paired (first and last) isolates from PC subjects had minor genetic differences. Swabs from PC veterinarians carried higher numbers of S. aureus. Among IC veterinarians, culture positivity was significantly associated with recent contact with pigs. CONCLUSIONS: Exposure to pigs did not lead to prolonged colonization in most subjects, and the higher numbers of S. aureus in PC subjects suggests that unknown host factors may determine the likelihood of prolonged colonization by S. aureus of livestock origin. Exposure to S. aureus and persistent colonization of swine veterinarians was common but rarely associated with S. aureus disease.

Needlestick Injuries in Agriculture Workers and Prevention Programs.

There are a variety of biologics, vaccines, antibiotics, and hormones used in animal agriculture. Depending upon the procedure or pharmaceutical used, accidental injections or product exposures can result in mild to severe injuries. Needlestick injury (NSI) prevention, research, and education for veterinarians and agriculture workers is limited. The objective of this study was to collect and review published case reports and case series/surveys on human needlestick exposure to veterinary biologics and to summarize needlestick prevention strategies for agricultural workers/veterinarians. A search was conducted of PubMed and Centre for Agriculture Bioscience International (CABI) databases. References were reviewed to identify additional articles. NSI among agricultural workers were primarily included in this review. Thirty articles were applicable to exposures in agricultural settings. Relevant literature consisted of case reports, survey/case series articles, prevention documents, and background articles. Fifty-nine case patients were identified. Most of these cases were associated with exposures to specific vaccines or veterinary products. Injury location was identified from 36 individuals: 24 (67%) NSI to the hands, 10 (28%) injuries to the legs, and 2 to other body locations. Of the 59 cases, 20 (34%) involved oil-adjuvant vaccines. Evidence of hospitalization was recorded for 30 case patients. The length of hospitalization was available from 11 case patients. Median length of hospitalization was 3 days (range: 1-4). Surgical intervention was reported in 25 case patients. Outcome information was available on 30 case patients. Fifteen made a complete recovery within 2 weeks of treatment, 14 had residual sequelae attributed to the injury, and there was 1 reported death. Of the 13 survey/case series articles: 2 focused on oil-adjuvant products, 1 on Brucellosis RB-51 vaccine, 3 on tilmicosin, 1 on Salmonella enteritidis vaccine, 1 on high-pressure injection, and 5 were nonspecific. NSI in agriculture workers and veterinarians can result in significant bodily injury and loss of work. There is a need for varied and comprehensive educational programs for agricultural workers and veterinarians to prevent NSI on livestock operations.

Personal Protective Equipment Use and Handwashing Among Animal Farmers: A Multi-site Assessment.

The goal of this study was to compare and contrast the use of personal protective equipment (PPE) and the practice of handwashing among participants of four studies assessing poultry and swine farms in the midwestern United States and in Thailand. This largely descriptive exercise was designed to assess and compare the frequency of these protective practices among the study populations. There were a total of 1113 surveys analyzed across the four studies. The respondents included workers in direct contact with animals as well as flock owners and veterinarians tending to farms. Handwashing was the most common practice observed among all participants with 42% "always" and 35% "sometimes" washing their hands after contact with the animals. This practice was least common among Minnesota swine workers. Even Thai poultry farmers, who demonstrated the lowest overall PPE use, reported a higher frequency of handwashing. Mask use during animal farming activities ("always" or "sometimes") was least commonly practiced, ranging from 1% in Thailand to 26% among backyard poultry farmers in Minnesota. Minnesota poultry and swine farmers had similar frequencies of mask (26%) and glove use (51% and 49%). All other comparisons differed significantly across the four sites (p-values <0.05). The use of PPE in animal farming differed by study location and is likely related to prevalent norms in the respective regions. Overall, the use of PPE did not appear to be influenced by the particular animal (poultry or swine) being farmed. These findings may prove useful to regulating bodies and farm owners in formulating policy or planning strategies for improving personal hygiene practices in animal farming and preparing for influenza and other potential zoonotic disease outbreaks.

Herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria on dairy farms in Minnesota, USA.

This study aimed to identify herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria (STB) on dairy cattle farms in Minnesota, USA. After adjustment for farm size, risk factors included: use of total mixed ration (TMR) for lactating dairy cows [odds ratio (OR) = 3.0; 95% confidence interval (CI): 1.8 to 5.1], no use of monensin for weaned calves (OR = 4.8, 95% CI: 2.5, 9.3), and no use of decoquinate for preweaned calves (OR = 2.2, 95% CI: 1.4, 3.6). Fecal shedding of STB was more common in small herds (< 100 cows, OR = 3.6, 95% CI: 2.1, 6.2) than in large herds (≥ 100 cows). Herd management factors related to cattle feeding practices were associated with fecal shedding of STB.

Facteurs de risque au niveau du troupeau associés à l'excrétion fécale des bactéries encodant la toxine de Shiga dans les fermes laitières du Minnesota, États-Unis. Cette étude avait pour but d'identifier les facteurs de risque au niveau du troupeau associés à l'excrétion fécale de bactéries encodant la shiga-toxine dans les fermes de bovins laitiers au Minnesota, États-Unis. Après un ajustement pour la taille de la ferme, les facteurs de risque incluaient : l'utilisation de la ration mixte totale (RMT) pour les vaches laitières en lactation [rapport de cotes (RC) = 3,0; intervalle de confiance (IC) de 95 % : de 1,8 à 5,1], pas d'utilisation de monensin pour les veaux sevrés (RC = 4,8, IC de 95 % : 2,5, 9,3) et pas d'utilisation de décoquinate pour les veaux présevrés (RC = 2,2, IC de 95 % : 1,4, 3,6). L'excrétion fécale de la bactérie encodant la shiga-toxine était plus commune dans les petits troupeaux (< 100 vaches, RC = 3,6, IC de 95 % : 2,1, 6,2) que dans les grands troupeaux (≥ 100 vaches). Des facteurs de gestion du troupeau se rapportant aux pratiques d'alimentation du bétail ont été associés à l'excrétion fécale de la bactérie encodant la shiga-toxine.(Traduit par Isabelle Vallières).

Influenza A(H1N1)pdm09 virus among healthy show pigs, United States.

Within 5 months after the earliest detection of human influenza A(H1N1)pdm09 virus, we found molecular and culture evidence of the virus in healthy US show pigs. The mixing of humans and pigs at swine shows possibly could further the geographic and cross-species spread of influenza A viruses.

Salmonella infections in food workers identified through routine Public Health Surveillance in Minnesota: impact on outbreak recognition.

The frequency of Salmonella-infected food workers identified through routine surveillance from 1997 to 2004 in Minnesota was determined in order to evaluate the impact of surveillance on the detection of outbreaks in restaurants and to quantify the duration of Salmonella shedding in stool. Of 4,976 culture-confirmed Salmonella cases reported to the Minnesota Department of Health, 110 (2.2%) were identified as food workers; this was less than one-half the number expected based on the incidence of Salmonella in the general population. Twenty food workers (18%) were associated with outbreaks. Twelve were involved in nine independent outbreaks at the restaurants where they worked. The identification of the index food worker in six of these outbreaks was critical to the initiation of outbreak investigations that revealed much larger problems. Among food workers who submitted specimens until at least one negative result was obtained (n = 69), the median duration of shedding was 22 days (range, 1 to 359 days). Among the four most common serotypes (Enteritidis, Typhimurium, Heidelberg, and Newport) the median duration of shedding was significantly longer for Salmonella Newport (80 days; P = 0.02) and for Salmonella Enteritidis (32 days; P = 0.04) than for Salmonella Heidelberg (8 days). Food workers should be considered an important source of Salmonella transmission, and those identified through surveillance should raise a high index of suspicion of a possible outbreak at their place of work. Food service managers need to be alert to Salmonella-like illnesses among food workers to facilitate prevention and control efforts, including exclusion of infected food workers or restriction of their duties.

Cattle-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria on dairy farms, Minnesota, USA.

The objective of this study was to identify individual cattle-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria (STB), a surrogate for Shiga toxin-producing E. coli (STEC), on 28 organic and conventional dairy farms. It was found that small organic herds (fewer than 100 cows) were associated with higher odds of Shiga toxin-encoding bacteria (STB) shedding from 2 (all cattle and all cows) of 3 cattle models, followed by small conventional herds, compared with large conventional herds. Preweaned calves [odds ratio (OR) = 2.6, 95% confidence interval (CI): 1.2, 5.7] had higher odds of shedding STB compared with adult cows. Calves more than 28 days of age (OR = 2.0, 95%CI: 1.0, 4.4) were more likely to shed STB than calves less than 28 days of age. This information may be helpful for identifying potential control strategies such as targeted vaccination or management practices.

Outbreaks of salmonellosis in Minnesota (1998 through 2006) associated with frozen, microwaveable, breaded, stuffed chicken products.

From 1998 through 2006, four outbreaks of salmonellosis associated with raw, frozen, microwaveable, breaded, prebrowned, stuffed chicken products were identified in Minnesota. In 1998, 33 Salmonella Typhimurium cases were associated with a single brand of Chicken Kiev. In 2005, four Salmonella Heidelberg cases were associated with a different brand and variety (Chicken Broccoli and Cheese). From 2005 to 2006, 27 Salmonella Enteritidis cases were associated with multiple varieties of product, predominately of the same brand involved in the 1998 outbreak. In 2006, three Salmonella Typhimurium cases were associated with the same brand of product involved in the 2005 Salmonella Heidelberg outbreak. The outbreak serotype and pulsed-field gel electrophoresis subtype of Salmonella were isolated from product in each outbreak. In these outbreaks, most individuals affected thought that the product was precooked due to its breaded and prebrowned nature, most used a microwave oven, most did not follow package cooking instructions, and none took the internal temperature of the cooked product. Similar to previous salmonellosis outbreaks associated with raw, breaded chicken nuggets or strips in Canada and Australia, inadequate labeling, consumer responses to labeling, and microwave cooking were the key factors in the occurrence of these outbreaks. Modification of labels, verification of cooking instructions by the manufacturer, and notifications to alert the public that these products contain raw poultry, implemented because of the first two outbreaks, did not prevent the other outbreaks. Microwave cooking is not recommended as a preparation method for these types of products, unless they are precooked or irradiated prior to sale.

Antimicrobial susceptibility of Shiga toxin-producing Escherichia coli isolated from organic dairy farms, conventional dairy farms, and county fairs in Minnesota.

This study compared the antimicrobial susceptibility of Shiga toxin-producing Escherichia coli (STEC) isolates from organic dairy farms, conventional dairy farms, and Minnesota county fairs. A total of 83 STEC isolates (43 O157 and 40 non-O157 STEC) were tested for antimicrobial susceptibility as determined by the automated broth microdilution method. Resistance to tetracycline was identified in 19 (23%) isolates and to sulphadimethoxine in 40 (48%) isolates. Half of the STEC isolates were resistant to at least one antimicrobial agent. Resistance to at least one antimicrobial agent was observed in 18 (62%) isolates from conventional farms and in 11 (48%) isolates from organic farms. Resistance to at least one antimicrobial agent was more frequent in isolates from calves (77%) than from cows (39%). Multidrug resistant patterns were more common in non-O157 STEC than O157 STEC. This study provides data to document the degree of STEC antimicrobial resistance from dairy cattle sources in Minnesota. The use of antimicrobial agents on farms, and other environmental influences, may affect resistance patterns in isolates from cattle sources. Systematic surveillance of STEC from cattle could potentially detect emergence of antimicrobial resistance that may be spread to humans through the food chain.

Prevalence of shiga toxin-encoding bacteria and shiga toxin-producing Escherichia coli isolates from dairy farms and county fairs.

Shiga toxin-encoding bacteria (STB) and shiga toxin-producing Escherichia coli (STEC) were detected and isolated from dairy cattle and their farm environment and from manure piles at Minnesota (MN) county fairs from 2001 to 2002. A total of 2,540 samples were collected from 28 dairy cattle farms (8 organic and 20 conventional), 17 calf pens (5 organic and 12 conventional), and 12 county fairs. STB were detected from 71 (3.2%) of 2208 fecal samples with 20 (71.4%) of 28 dairy farms having at least one positive animal sample. In samples collected from conventional farms, 41 (2.3%) of 1750 fecal samples were STB-positive and 13 (65%) of 20 farms had at least one positive animal. Thirty (6.6%) of 458 fecal samples from organic farms were STB-positive and 7 (87.5%) of 8 farms had at least one positive animal. STB was detected from 31 (17.4%) of 178 samples and 7 (58.3%) out of 12 manure piles at county fairs. A total of 43 STEC isolates were recovered and belonged to 26 different serotypes (19 O and 18 H types). Among STEC, 60.5% possessed only stx1, 30.2% stx2, and 9.3% both stx1 and stx2. The genes eae and hlyA were detected in more than 50% of the STEC isolates. STB can be found on most dairy cattle farms including organic and conventional herds and county fairs. The presence of these potentially pathogenic bacteria in county fairs may pose a risk to the public who have contact with cattle or their environment.

Recent animal disease outbreaks and their impact on human populations.

Over the past 20 years, headlines have documented an increasing number of emerging diseases; most have an animal source (zoonoses). Recent examples include West Nile virus, severe acute respiratory syndrome (SARS), avian influenza, and monkeypox. While some emerging diseases occur among both humans and animals, others affect only animals or only humans. Nevertheless, all these new or reemerging infections have societal implications, often tied to local and national economies. It is important to understand the implications of emerging animal diseases and encourage stronger collaboration of veterinary and medical practitioners, especially in rural areas. Illnesses in agricultural workers may be the index cases for newly emerging diseases.

Salmonella outbreaks in restaurants in Minnesota, 1995 through 2003: evaluation of the role of infected foodworkers.

The 23 restaurant-associated salmonellosis outbreaks that occurred in Minnesota from 1995 through 2003 were reviewed to characterize the role of infected foodworkers. The median duration of the outbreaks was 21 days (range, 1 to 517 days). The median number of culture-confirmed patron cases per outbreak was seven (range, 1 to 36 cases). The median incubation for patron cases ranged from 9 h to 5.9 days. A specific food vehicle was implicated in four outbreaks and suspected in five. Salmonella of the same serotype and pulsed-field gel electrophoresis subtype as that found in patrons was recovered from foodworkers in 19 outbreaks. Overall, 12% (129 of 1,033) of foodworkers tested positive for Salmonella. Sixty-four (53%) of 121 Salmonella-positive foodworkers reported not having had a recent gastrointestinal illness. Overall, the median duration of Salmonella shedding was 16 days. Among foodworkers who reported gastrointestinal illness, the median shedding duration was 30 days as compared with 3 days for asymptomatic foodworkers. Positive environmental samples were recovered in 4 (33%) of 12 outbreaks. No specific food vehicle was identified in any outbreaks associated with Salmonella-positive environmental samples. The median duration of outbreaks with positive environmental samples (187 days) was significantly longer than the median duration of outbreaks with negative environmental results (26 days, P = 0.03). A higher proportion of Salmonella-positive foodworkers (22 versus 8%) was identified in outbreaks with positive environmental samples. Salmonella outbreaks in restaurants are frequently prolonged yet produce a small number of confirmed patron cases. Prolonged outbreak durations suggest a persistent reservoir of contamination. Infected foodworkers likely serve as an important source for Salmonella transmission. Therefore, assessment of foodworker infection is essential for controlling restaurant outbreaks.

Emergence of multidrug-resistant Salmonella enterica serotype Newport in Minnesota.

We report a concurrent increase in the number of isolates of Salmonella enterica serotype Newport and the rate of multidrug resistance in S. Newport isolates from animal and human populations in Minnesota. Antimicrobial susceptibility and pulsed-field gel electrophoresis analysis demonstrated heterogeneity of isolates and showed that 1 pulsed-field gel electrophoresis cluster contained most of the multidrug-resistant isolates with a resistance pattern and most class 1 integron isolates, implying the clonal origin of the isolates.

Prevalence and characterization of Escherichia coli O157 isolates from Minnesota dairy farms and county fairs.

Samples were collected from 26 organic and conventional farms and 12 county fairs in Minnesota during 2001 and 2002 to identify the presence of Escherichia coli O157. Immunomagnetic separation was used for isolation of E. coli O157. Isolates were further characterized by the presence of virulence marker genes (stx1, stx2, eaeA, E-hly, katP, etpD, and espP), antimicrobial susceptibility profiles, and genotypes. During 2001, E. coli O157 was isolated from 16 (5.2%) of 305 fecal samples and from 7 (36.8%) of 19 farms. During 2002, E. coli O157 was isolated from 6 (4.5%) of 132 fecal samples from weaned calves at 4 (23.5%) of 17 farms. During 2001 and 2002, cattle manure samples were collected from 12 county fairs, and E. coli O157 was isolated from 19 (11%) of 178 samples and 9 (75%) of 12 county fairs. Among 40 E. coli O157 isolates, 17 isolates (43%) had both the stx1 and stx2 genes, and 21 strains (53%) had the stx2 gene only. Thirteen percent of O157 isolates were resistant to tetracycline, and 25% were resistant to sulfadimethoxine. Heterogeneity of E. coli O157 strains was demonstrated by the presence of 22 different pulsed-field gel electrophoresis (PFGE) patterns. Four PFGE patterns matched those of isolates previously found in humans. The presence of E. coli O157 at county fairs suggests the potential for transmission to the public, who may have contact with cattle or their environment.