Estimate of the annual burden of foodborne illness in nondeployed active duty US Army Service Members: five major pathogens, 2010-2015.

In this study, we estimate the burden of foodborne illness (FBI) caused by five major pathogens among nondeployed US Army service members. The US Army is a unique population that is globally distributed, has its own food procurement system and a food protection system dedicated to the prevention of both unintentional and intentional contamination of food. To our knowledge, the burden of FBI caused by specific pathogens among the US Army population has not been determined. We used data from a 2015 US Army population survey, a 2015 US Army laboratory survey and data from FoodNet to create inputs for two model structures. Model type 1 scaled up case counts of Campylobacter jejuni, Shigella spp., Salmonella enterica non-typhoidal and STEC non-O157 ascertained from the Disease Reporting System internet database from 2010 to 2015. Model type 2 scaled down cases of self-reported acute gastrointestinal illness (AGI) to estimate the annual burden of Norovirus illness. We estimate that these five pathogens caused 45 600 (5%-95% range, 30 300-64 000) annual illnesses among nondeployed active duty US Army Service members. Of these pathogens, Norovirus, Campylobacter jejuni and Salmonella enterica non-typhoidal were responsible for the most illness. There is a tremendous burden of AGI and FBI caused by five major pathogens among US Army Soldiers, which can have a tremendous impact on readiness of the force. The US Army has a robust food protection program in place, but without a specific active FBI surveillance system across the Department of Defence, we will never have the ability to measure the effectiveness of modern, targeted, interventions aimed at the reduction of specific foodborne pathogens.

Magnitude, distribution, risk factors and care-seeking behaviour of acute, self-reported gastrointestinal illness among US Army Soldiers: 2015.

Throughout history, acute gastrointestinal illness (AGI) has been a significant cause of morbidity and mortality among US service members. We estimated the magnitude, distribution, risk factors and care seeking behaviour of AGI among the active duty US Army service members using a web-based survey. The survey asked about sociodemographic characteristics, dining and food procurement history and any experience of diarrhoea in the past 30 days. If respondents reported diarrhoea, additional questions about concurrent symptoms, duration of illness, medical care seeking and stool sample submission were asked. Univariable and multivariable logistic regression were used to identify the factors associated with AGI and factors associated with seeking care and submitting a stool sample. The 30-day prevalence of AGI was 18.5% (95% CI 16.66-20.25), the incidence rate was 2.24 AGI episodes per person-year (95% CI 2.04-2.49). Risk factors included a region of residence, eating at the dining facility and eating at other on-post establishments. Individuals with AGI missed 2.7-3.7 days of work, which costs approximately $ 847 451 629 in paid wages. Results indicate there are more than 1 million cases of AGI per year among US Army Soldiers, which can have a major impact on readiness. We found that care-seeking behaviours for AGI are different among US Army Service Members than the general population. Army Service Members with AGI report seeking care and having a stool sample submitted less often, especially for severe (bloody) diarrhoea. Factors associated with seeking care included rank, experiencing respiratory symptoms (sore throat, cough), experiencing vomiting and missing work for their illness. Factors associated with submitting a stool sample including experiencing more than five loose stools in 24 h and not experiencing respiratory symptoms. US Army laboratory-based surveillance under-estimates service members with both bloody and non-bloody diarrhoea. To our knowledge, this is the first study to estimate the magnitude, distribution, risk factors and care-seeking behaviour of AGI among Army members. We determined Army service members care-seeking behaviours, AGI risk factors and stool sample submission rates are different than the general population, so when estimating burden of AGI caused by specific foodborne pathogens using methods like Scallan et al. (2011), unique multipliers must be used for this subset of the population. The study legitimises not only the importance of AGI in the active duty Army population but also highlights opportunities for public health leaders to engage in simple strategies to better capture AGI impact so more modern intervention strategies can be implemented to reduce burden and indirectly improve operational readiness across the Enterprise.

Climate, lactation, and treatment factors influence faecal shedding of Escherichia coli O157 pathotypes in dairy cows.

Among pathogens shed by cattle, Escherichia coli O157 ranks highest in those causing human illness. To date, prevalence and risk factors for O157 shedding have been assessed in feedlot, but not dairy cattle. The study aimed to determine prevalence levels and risk factors for O157 atypical enteropathogenic E. coli (aEPEC) and enterohaemorrhagic E. coli (EHEC) shedding in dairy cattle. Dairy cattle (n = 899) within the first 21 days of lactation were sampled monthly over the course of 1 year, on three dry lot dairies surrounding Fort Collins, CO. During visits multiple factors were measured (disease history, pharmaceutical use, climate measures, etc.), and cattle faeces were collected and assessed for presence of O157 and virulence genes. Logistic regression analysis was performed using O157 outcomes and measured factors. Prevalence of O157 aEPEC was 3·7%, while EHEC was 3·0%. Many potential risk factors were highly correlated, and used to build separate multivariable models. An increase in humidity was positively associated with aEPEC, while fluid faeces and history of disease showed a negative association. Meanwhile, an increase in temperature and antibiotic treatment was positively associated with EHEC, while more days in milk, higher hygiene score and cow contact were negatively associated. These results may guide mitigation strategies that reduce O157 shedding, and contamination of the human food chain.

Rapid Salmonella detection in experimentally inoculated equine faecal and veterinary hospital environmental samples using commercially available lateral flow immunoassays.

REASONS FOR PERFORMING STUDY: Salmonella enterica is the most commonly reported cause of outbreaks of nosocomial infections in large animal veterinary teaching hospitals and the closure of equine hospitals. Rapid detection may facilitate effective control practices in equine populations. Shipping and laboratory testing typically require ≥48 h to obtain results. Lateral flow immunoassays developed for use in food-safety microbiology provide an alternative that has not been evaluated for use with faeces or environmental samples. OBJECTIVES: We aimed to identify enrichment methods that would allow commercially available rapid Salmonella detection systems (lateral flow immunoassays) to be used in clinical practice with equine faecal and environmental samples, providing test results in 18-24 h. STUDY DESIGN: In vitro experiment. METHODS: Equine faecal and environmental samples were inoculated with known quantities of S. enterica serotype Typhimurium and cultured using 2 different enrichment techniques for faeces and 4 enrichment techniques for environmental samples. Samples were tested blindly using 2 different lateral flow immunoassays and plated on agar media for confirmatory testing. RESULTS: In general, commercial lateral flow immunoassays resulted in fewer false-negative test results with enrichment of 1 g faecal samples in tetrathionate for 18 h, while all environmental sample enrichment techniques resulted in similar detection rates. The limit of detection from spiked samples, ∼4 colony-forming units/g, was similar for all methods evaluated. CONCLUSIONS: The lateral flow immunoassays evaluated could reliably detect S. enterica within 18 h, indicating that they may be useful for rapid point-of-care testing in equine practice applications. Additional evaluation is needed using samples from naturally infected cases and the environment to gain an accurate estimate of test sensitivity and specificity and to substantiate further the true value of these tests in clinical practice.

Efficacy of intranasal administration of a modified live feline herpesvirus 1 and feline calicivirus vaccine against disease caused by Bordetella bronchiseptica after experimental challenge.

BACKGROUND: Studies suggest that intranasal vaccination can stimulate nonspecific immunity against agents not contained within the vaccine, but this effect is not reported for cats. HYPOTHESIS: A modified live feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV) intranasal vaccine will reduce clinical signs of disease caused by experimental infection with Bordetella bronchiseptica. ANIMALS: Twenty specific pathogen-free 12-week-old kittens. METHODS: Experimental study. Cats were randomized into 2 groups of 10 cats each. The vaccinated group was administered a single intranasal dose of a commercially available vaccine containing modified live strains of FHV-1 and FCV, and the control group remained unvaccinated. All 20 cats were administered B. bronchiseptica by nasal inoculation 7 days later and were observed daily for clinical signs of illness for 20 days. RESULTS: In the first 10 days after B. bronchiseptica challenge, vaccinated cats were less likely to be clinically ill than control cats with a median clinical score of 0/180 (range 0-5) versus 2/180 (range 0-8) (P = .01). Nine of 10 control cats and 2 of 10 vaccinated cats were recorded as sneezing during days 1-10 after challenge (P = .006). CONCLUSIONS AND CLINICAL IMPORTANCE: Intranasal vaccination against FHV-1 and FCV decreased signs of illness due to an infectious agent not contained in the vaccine. This nonspecific immunity could be beneficial for protection against organisms for which vaccines are not available and as protection before development of vaccine-induced humoral immunity.

Risk associated with transportation and lairage on hide contamination with Salmonella enterica in finished beef cattle at slaughter.

Transportation of cattle to the slaughter plant could influence hide contamination with Salmonella enterica. Fecal and hide samples were obtained from 40 lots of cattle at the feedlot and again at the slaughter plant. Potential risk factors for hide contamination were evaluated. A multilevel Poisson regression model was used to determine whether transportation and lairage were associated with hide contamination by Salmonella. Cattle with hide samples positive for Salmonella at the feedlot had twice the risk of having positive slaughter hide samples compared with cattle without positive feedlot hide samples (relative risk [RR], 1.9). Cattle transported in trailers from which samples positive for Salmonella were collected had twice the risk of having positive slaughter hide samples compared with cattle transported in culture-negative trailers (RR, 2.3). Cattle transported for long distances had twice the risk of having positive hide samples at slaughter compared with cattle transported shorter distances (RR, 2.3). Cattle held in lairage pens contaminated with feces had twice the risk of having positive slaughter hide samples compared with cattle held in clean pens (RR, 1.8). Cattle held off feed longer than 18 h before loading had twice the risk of having positive slaughter hide samples compared with cattle held off feed for shorter times (RR, 1.7). Cattle that were agitated during loading had twice the risk of having positive slaughter hide samples compared with cattle that were calm (RR, 2.2). These findings suggest that variables associated with transportation and lairage can impact the presence of Salmonella on the hides of cattle at slaughter.

Impact of transportation and lairage on hide contamination with Escherichia coli O157 in finished beef cattle.

Transportation of cattle from the feedlot to the slaughter plant could influence hide contamination of Escherichia coli O157. A study was initiated to investigate the influence of transportation and lairage on shedding and hide contamination of E. coli O157. Fecal and hide samples were obtained from 40 pens of harvest-ready beef cattle at the feedlot prior to transport and again at the slaughter plant immediately after slaughter. Potential risk factors for hide contamination at the feedlot, during transport, and at slaughter were evaluated. A multilevel Poisson regression model was used to evaluate if transportation and lairage were associated with hide contamination by E. coli O157 in finished beef cattle. Lots of cattle held in E. coli O157-positive lairage pens had eight times greater risk of having positive slaughter hide samples compared with cattle held in culture-negative pens (relative risk, 8.0; 95% confidence interval, 1.6 to 38.8). Lots of cattle that were held in lairage pens contaminated with feces had three times greater risk for positive slaughter hide samples compared with cattle held in clean pens (relative risk, 3.1; 95% confidence interval, 1.2 to 7.9). Lots of cattle that were transported for long distances (> 160.9 km) had twice the risk of having positive hide samples at slaughter compared with cattle transported a shorter distance (relative risk, 2.4; 95% confidence interval, 1.1 to 5.1). These findings suggest that transportation and lairage should be considered in E. coli O157 control strategies.

Comparison of Salmonella enterica serotype Infantis isolates from a veterinary teaching hospital.

AIMS: To compare Salmonella enterica serotype Infantis isolates obtained from patients or the environment of a veterinary teaching hospital over a period of 9 years following a nosocomial outbreak to determine whether isolates were epidemiologically related or represented unrelated introductions into the hospital environment. METHODS AND RESULTS: Fifty-six S. Infantis isolates were compared based on their phenotypic (antimicrobial drug [AMD] susceptibility pattern) and genotypic (pulsed-field gel electrophoresis [PFGE] pattern and presence of integrons) characteristics. Epidemiologically unrelated S. Infantis isolates clustered separately from all but two of the hospital isolates, and several isolates from different years and various sources were indistinguishable from each other in cluster analysis of two-enzyme PFGE results. A high percentage of isolates (80.3%) were resistant to at least one AMD, with 67.8% showing resistance to >5 AMD. The majority (74.1%) of isolates tested contained type 1 integrons. CONCLUSION: Results strongly suggest that there was nosocomial transmission of S. Infantis during the initial outbreak, and that contamination arising from this outbreak persisted across years despite rigorous hygiene and biosecurity precautions and may have led to subsequent nosocomial infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Evidence of persistence and transmission of Salmonella clones across years, even in the face of rigorous preventive measures, has important implications for other facilities that have experienced outbreaks of Salmonella infections.

Prevalence and antibiotic susceptibility of Salmonella isolated from beef animal hides and carcasses.

This study determined the prevalence of Salmonella on beef animal hides and carcasses and antimicrobial susceptibility profiles against a panel of 13 antibiotics. In each of the eight commercial packing facilities, of which five processed primarily heifers and steers and the remaining three processed primarily cows and bulls, hide and carcass sponge swab samples were obtained immediately before hide removal and before carcass chilling, respectively. Overall, prevalence of Salmonella on external surfaces (hides) of cattle was 15.4% (49 of 319), whereas prevalence after dehiding and other slaughtering/dressing processes, including the application of decontamination treatments, was, as expected, reduced (P < 0.05) to 1.3% (4 of 320) on carcass surfaces. From 53 total Salmonella-positive hide and carcass samples, 526 biochemically confirmed isolates were obtained to determine antimicrobial susceptibility profiles. Of 53 Salmonella-positive samples, individually, 24 (45.3%), 17 (32.1%), 17 (32.1%), 11 (20.8%), 8 (15.1%), 8 (15.1%), 8 (15.1%), 4 (7.5%), and 2 (3.8%) samples yielded at least one isolate resistant to amoxicillin/clavulanic acid, tetracycline, streptomycin, sulfonamides, ampicillin, ampicillin/sulbactam, chloramphenicol, gentamicin, and trimethoprim/sulfamethoxazole, respectively. None of the Salmonella-positive samples yielded an isolate resistant to ceftriaxone, ciprofloxacin, enrofloxacin, or levofloxacin. Although none of the samples yielded an isolate simultaneously resistant to three or four antimicrobials, a total of eight samples yielded at least one isolate resistant to five or more antimicrobials tested. Included among the 18 group B-positive samples were three samples that, individually, yielded at least one Salmonella Typhimurium var. Copenhagen DT104 isolate resistant to at least six antimicrobials tested. Results from this study support current prudent therapeutic and subtherapeutic antimicrobial use recommendations.

Prevalence, antibiotic susceptibility, and diversity of Escherichia coli O157:H7 isolates from a longitudinal study of beef cattle feedlots.

Prevalence, antibiotic susceptibility, and genetic diversity were determined for Escherichia coli O157:H7 isolated over 11 months from four beef cattle feedlots in southwest Kansas. From the fecal pat (17,050) and environmental (7,134) samples collected, 57 isolates of E. coli O157:H7 were identified by use of bacterial culture and latex agglutination (C/LA). PCR showed that 26 isolates were eaeA gene positive. Escherichia coli O157:H7 was identified in at least one of the four feedlots in 14 of the 16 collections by C/LA and in 9 of 16 collections by PCR, but consecutive positive collections at a single feedlot were rare. Overall prevalence in fecal pat samples was low (0.26% by C/LA, and 0.08% by PCR). No detectable differences in prevalence or antibiotic resistance were found between isolates collected from home pens and those from hospital pens, where antibiotic use is high. Resistant isolates were found for six of the eight antibiotics that could be used to treat E. coli infections in food animals, but few isolates were multidrug resistant. The high diversity of isolates as measured by random amplification of polymorphic DNA and other characteristics indicates that the majority of isolates were unique and did not persist at a feedlot, but probably originated from incoming cattle. The most surprising finding was the low frequency of virulence markers among E. coli isolates identified initially by C/LA as E. coli O157:H7. These results demonstrate that better ways of screening and confirming E. coli O157:H7 isolates are required for accurate determination of prevalence.

Usefulness of a commercially available enzyme immunoassay for Shiga-like toxins I and II as a presumptive test for the detection of Escherichia coli O157:H7 in cattle feces.

The performance of a commercially available enzyme immunoassay (EIA) for determining the presence of Shiga toxin I and II in human diarrheal stool samples was evaluated for use as a presumptive test for the presence of Escherichia coli O157:H7 in nondiarrheal bovine fecal samples collected from 10 Kansas cow-calf ranches. The prevalence of E. coli O157:H7 in 2,297 samples, as determined by selective bacterial culture, was 1.6%. The sample prevalence of non-E. coli O157:H7 Shiga toxin-producing bacteria, as detected by the Shiga toxin EIA, was 5.8%. Only 2 of 136 samples that tested positive with the Shiga toxin EIA were positive for E. coli O157:H7 by culture. Compared with bacterial culture, the sensitivity of the Shiga toxin EIA was 5.5% and the specificity was 94.1%. Agreement between the 2 tests, as measured by the kappa statistic, was poor (kappa = -0.002). Although the Shiga toxin EIA was not a good presumptive test for the determination of E. coli O157:H7 in bovine fecal samples because of its low sensitivity (5.5%), it might be a useful test for the detection of Shiga toxin producing non-E. coli O157:H7 organisms in bovine feces.

Results of a longitudinal study of the prevalence of Escherichia coli O157:H7 on cow-calf farms.

OBJECTIVE: To describe the frequency and distribution of Escherichia coli O157:H7 in the feces and environment of cow-calf herds housed on pasture. SAMPLE POPULATION: Fecal and water samples for 10 cow-calf farms in Kansas. PROCEDURE: Fecal and water samples were obtained monthly throughout a 1-year period (3,152 fecal samples from 2,058 cattle; 199 water samples). Escherichia coli O157:H7 in fecal and water samples was determined, using microbial culture. RESULTS: Escherichia coli O157:H7 was detected in 40 of 3,152 (1.3%) fecal samples, and 40 of 2,058 (1.9%) cattle had > or = 1 sample with E coli. Fecal shedding by specific cattle was transient; none of the cattle had E coli in more than 1 sample. Significant differences were not detected in overall prevalence among farms. However, significant differences were detected in prevalence among sample collection dates. Escherichia coli O157:H7 was detected in 3 of 199 (1.5%) water samples. CONCLUSIONS AND CLINICAL RELEVANCE: Implementing control strategies for E coli O157:H7 at all levels of the cattle industry will decrease the risk of this organism entering the human food chain. Devising effective on-farm strategies to control E coli O157:H7 in cow-calf herds will require an understanding of the epidemiologic characteristics of this pathogen.

Analysis of the lytic activity of the Serpulina hyodysenteriae hemolysin.

The hemolysins of Serpulina hyodysenteriae are active at 27 to 40 degrees C and pH 3 to 9 and are unaffected by enzymatic inhibitors. Pore formation was demonstrated by the inhibition of hemolysis with molecules of 2.0 to 2.3 nm in diameter and the release of 86rubidium from erythrocytes without hemoglobin release after exposure to native hemolysin.

Reduced virulence of Serpulina hyodysenteriae hemolysin-negative mutants in pigs and their potential to protect pigs against challenge with a virulent strain.

The role of the Serpulina hyodysenteriae hemolysin encoded by the tlyA gene in the pathogenesis of swine dysentery (SD) was studied. tlyA mutants of two S. hyodysenteriae strains (B204 and C5) were tested for virulence in pigs. None of the animals developed SD. However, after infection with wild-type strain B204 or C5, the incidence of SD was 100 or 60%, respectively. Thus, the tlyA-encoded hemolysin of S. hyodysenteriae is an important virulence factor in SD. The potential of these mutants to protect pigs against challenge with a virulent S. hyodysenteriae strain was also studied. After challenge with wild-type strain B204, 50% of pigs previously inoculated with the B204 tlyA mutant were protected, whereas all control pigs contracted SD. None of the pigs previously inoculated with the C5 tlyA mutant developed SD upon challenge with wild-type strain B204, whereas 40% of the control pigs developed SD in this experiment. Thus, previous colonization with S. hyodysenteriae tlyA mutants in pigs provides partial protection against challenge with a virulent S. hyodysenteriae strain.