Optimal Levels of Inputs to Control Listeria monocytogenes Contamination at a Smoked Fish Plant

Reducing the incidence of listeriosis from contaminated food has significant social health benefits, but reduction requires the use of additional or higher quality inputs at higher costs. We estimate the impact of three inputs in a food processing plant on the prevalence of L. monocytogenes contaminated finished cold smoked salmon. These three inputs were non-contamination of the raw fish fillets, non-contamination of the plant environment, and rate of glove changes on workers. We then estimate the levels of these inputs to use such that the marginal cost of these inputs become equal to the increased social health benefit of reduction in human listeriosis. Since the costs of these inputs are borne by the food processing plant, which may not be able to secure a higher product price because of asymmetric information, we show how social sub-optimal use of these inputs may result.Food Consumption/Nutrition/Food Safety,

VISOKO GOSPODARSKO UČILIŠTE U KRIŽEVCIMA PRILOG OBRAZOVANJU ZA ODRŽIVU I EKOLOŠKU POLJOPRIVREDU

The paper presents an overview of the role of the Križevci College of Agriculture within the professionally-oriented higher education and its contribution to sustainable and organic agriculture education. It gives a brief description of the past and present-day College focusing on its current agriculture study courses, i.e. the three-year professional courses (bachelor level), two-year specialist graduate professional course titled Sustainable and Organic Agriculture (master level) and specialist seminars as part of lifelong learning.Rad daje pregled uloge koju ima Visoko gospodarsko učilište u Križevcima u području stručnih studija za poljoprivredu u Hrvatskoj i doprinos visokoškolskom obrazovanju za održivu i ekološku poljoprivredu. U radu se također donosi kratki opis povijesnoga razvoja križevačkoga Učilišta i opis suvremenih studijskih programa na razini stručnog i specijalističkog diplomskog studija te specijalističkih seminara u sklopu cjeloživotnoga učenja

Salmonella Fecal Shedding and Immune Responses are Dose- and Serotype- Dependent in Pigs

Despite the public health importance of Salmonella infection in pigs, little is known about the associated dynamics of fecal shedding and immunity. In this study, we investigated the transitions of pigs through the states of Salmonella fecal shedding and immune response post-Salmonella inoculation as affected by the challenge dose and serotype. Continuous-time multistate Markov models were developed using published experimental data. The model for shedding had four transient states, of which two were shedding (continuous and intermittent shedding) and two non-shedding (latency and intermittent non-shedding), and one absorbing state representing permanent cessation of shedding. The immune response model had two transient states representing responses below and above the seroconversion level. The effects of two doses [low (0.65×106 CFU/pig) and high (0.65×109 CFU/pig)] and four serotypes (Salmonella Yoruba, Salmonella Cubana, Salmonella Typhimurium, and Salmonella Derby) on the models' transition intensities were evaluated using a proportional intensities model. Results indicated statistically significant effects of the challenge dose and serotype on the dynamics of shedding and immune response. The time spent in the specific states was also estimated. Continuous shedding was on average 10–26 days longer, while intermittent non-shedding was 2–4 days shorter, in pigs challenged with the high compared to low dose. Interestingly, among pigs challenged with the high dose, the continuous and intermittent shedding states were on average up to 10–17 and 3–4 days longer, respectively, in pigs infected with S. Cubana compared to the other three serotypes. Pigs challenged with the high dose of S. Typhimurium or S. Derby seroconverted on average up to 8–11 days faster compared to the low dose. These findings highlight that Salmonella fecal shedding and immune response following Salmonella challenge are dose- and serotype-dependent and that the detection of specific Salmonella strains and immune responses in pigs are time-sensitive

Formation of escherichia coli O157: H7 Persister Cells in the Lettuce Phyllosphere and Application of Differential Equation Models to Predict Their Prevalence on Lettuce Plants in the Field

American Society for Microbiology. Escherichia coli O157:H7 (EcO157) infections have been recurrently associated with produce. The physiological state of EcO157 cells surviving the many stresses encountered on plants is poorly understood. EcO157 populations on plants in the field generally follow a biphasic decay in which small subpopulations survive over longer periods of time. We hypothesized that these subpopulations include persister cells, known as cells in a transient dormant state that arise through phenotypic variation in a clonal population. Using three experimental regimes (with growing, stationary at carrying capacity, and decaying populations), we measured the persister cell fractions in culturable EcO157 populations after inoculation onto lettuce plants in the laboratory. The greatest average persister cell fractions on the leaves within each regime were 0.015, 0.095, and 0.221%, respectively. The declining EcO157 populations on plants incubated under dry conditions showed the largest increase in the persister fraction (46.9-fold). Differential equation models were built to describe the average temporal dynamics of EcO157 normal and persister cell populations after inoculation onto plants maintained under low relative humidity, resulting in switch rates from a normal cell to a persister cell of 7.7×10-6 to 2.8×10-5 h-1. Applying our model equations from the decay regime, we estimated model parameters for four published field trials of EcO157 survival on lettuce and obtained switch rates similar to those obtained in our study. Hence, our model has relevance to the survival of this human pathogen on lettuce plants in the field. Given the low metabolic state of persister cells, which may protect them from sanitization treatments, these cells are important to consider in the microbial decontamination of produce. Despite causing outbreaks of foodborne illness linked to lettuce consumption, E. coli O157:H7 (EcO157) declines rapidly when applied onto plants in the field, and few cells survive over prolonged periods of time. We hypothesized that these cells are persisters, which are in a dormant state and which arise naturally in bacterial populations. When lettuce plants were inoculated with EcO157 in the laboratory, the greatest persister fraction in the population was observed during population decline on dry leaf surfaces. Using mathematical modeling, we calculated the switch rate from an EcO157 normal to persister cell on dry lettuce plants based on our laboratory data. The model was applied to published studies in which lettuce was inoculated with EcO157 in the field, and switch rates similar to those obtained in our study were obtained. Our results contribute important new knowledge about the physiology of this virulent pathogen on plants to be considered to enhance produce safety

Assessment of the Variation Associated with Repeated Measurement of Gastrointestinal Transit Times and Assessment of the Effect of Oral Ranitidine on Gastrointestinal Transit Times Using a Wireless Motility Capsule System in Dogs

This study aimed to evaluate the variation associated with repeated measurement of gastrointestinal (GI) transit times and the effect of oral ranitidine on GI transit times in healthy dogs using a wireless motility capsule (WMC) system. Eight privately owned healthy adult dogs were enrolled, and one developed diarrhea and was removed from the study. For the first 3 repetitions, each dog was fed a standard meal followed by oral administration of a WMC. For the 4th repetition, each dog was given ranitidine hydrochloride (75 mg PO every 12 hours) prior to and during assessment of GI transit times. Mean between-subject coefficients of variation for gastric emptying time (GET), small and large bowel transit time (SLBTT), and total transit time (TTT) were 26.9%, 32.3%, and 19.6%, respectively. Mean within-subject coefficients of variation for GET, SLBTT, and TTT were 9.3%, 19.6%, and 15.9%, respectively. Median GET, SLBTT, and TTT without ranitidine were 719, 1,636, and 2,735 minutes, respectively. Median GET, SLBTT, and TTT with ranitidine were 757, 1,227, and 2,083 minutes, respectively. No significant differences in GI transit times were found between any of the 4 repetitions. Under these experimental conditions, no significant effects of oral ranitidine on GI transit times were observed

Importance of knowledge of language for special purposes regarding mobility and employability of Križevci college of agriculture graduates

U ovom se radu sustavno istražuju stavovi studenata Visokoga gospodarskog učilišta u Križevcima vezani uz važnost stranog jezika struke za mobilnost i zapošljivost. Prvi dio rada daje teoretsku podlogu istraživanju i definira strani jezik struke u kontekstu mobilnosti i zapošljivosti. U središnjem dijelu rada opisuje se istraživanje i analiza rezultata istraživanja provedenog metodom upitnika na populaciji ispitanika od 132 redovita studenta prve i druge godine Stručnog studija poljoprivrede. Većina studenata smatra kako je strani jezik kao kolegij potreban na Učilištu, te da će moduli iz stranog jezika koji su ponuđeni biti korisni u njihovom budućem zanimanju. Isto tako, većina njih smatra kako je znanje stranog jezika uvelike dobilo na značenju ulaskom Hrvatske u Europsku uniju, te da će njihovim budućim poslodavcima znanje stranog jezika biti važno prilikom njihovog zapošljavanja. Učenje stranih jezika trebalo bi biti sastavni dio obrazovanja na svim njegovim razinama, uključujući i visoko obrazovanje. Ulaskom u Europsku uniju ulazimo u krug jezične i kulturne raznolikosti, te će znanje stranog jezika biti izuzetno važno.This paper elaborates on attitudes of the students of Križevci College of Agriculture regarding the importance of language for special purposes for mobility and employability. The first part of the paper provides theoretical background for research and defines language for specific purposes in the context of mobility and employability. Central part of the paper describes research methods and analysis of research carried out on 132 full time students of Professional study programme of agriculture. Most students are of the opinion that foreign language is an important course subject and that such knowledge and skills will be useful in their future occupation. They also believe that foreign language knowledge became increasingly important with Croatian membership in the EU and that their future employers will favour those job candidates with better foreign language skills. Foreign languages should be an integral part of education at all levels, including the level of higher education. EU membership puts us in the circle of linguistic and cultural diversity and knowledge of foreign languages will become increasingly important

Exploratory spatial analysis of Lyme disease in Texas –what can we learn from the reported cases?

Background Lyme disease (LD) is a tick-borne zoonotic illness caused by the bacterium Borrelia burgdorferi. Texas is considered a non-endemic state for LD and the spatial distribution of the state’s reported LD cases is unknown. Methods We analyzed human LD cases reported to the Texas Department of State Health Services (TX-DSHS) between 2000 and 2011 using exploratory spatial analysis with the objective to investigate the spatial patterns of LD in Texas. Case data were aggregated at the county level, and census data were used as the population at risk. Empirical Bayesian smoothing was performed to stabilize the variance. Global Moran’s I was calculated to assess the presence and type of spatial autocorrelation. Local Indicator of Spatial Association (LISA) was used to determine the location of spatial clusters and outliers. Results and Discussion There was significant positive spatial autocorrelation of LD incidence in Texas with Moran’s I of 0.41 (p = 0.001). LISA revealed significant variation in the spatial distribution of human LD in Texas. First, we identified a high-risk cluster in Central Texas, in a region that is thought to be beyond the geographical range of the main vector, Ixodes scapularis. Second, the eastern part of Texas, which is thought to provide the most suitable habitat for I. scapularis, did not appear to be a high-risk area. Third, LD cases were reported from several counties in western Texas, a region considered unsuitable for the survival of Ixodes ticks. Conclusions These results emphasize the need for follow-up investigations to determine whether the identified spatial pattern is due to: clustering of misdiagnosed cases, clustering of patients with an out-of state travel history, or presence of a clustered unknown enzootic cycle of B. burgdorferi in Texas. This would enable an improved surveillance and reporting of LD in Texas

Interacting Effects of Newcastle Disease Transmission and Illegal Trade on a Wild Population of White-Winged Parakeets in Peru: A Modeling Approach

Illegal wildlife-pet trade can threaten wildlife populations directly from overharvest, but also indirectly as a pathway for introduction of infectious diseases. This study evaluated consequences of a hypothetical introduction of Newcastle disease (ND) into a wild population of Peru's most trafficked psittacine, the white-winged parakeet (Brotogeris versicolurus), through release of infected confiscated individuals. We developed two mathematical models that describe ND transmission and the influence of illegal harvest in a homogeneous (model 1) and age-structured population of parakeets (model 2). Infection transmission dynamics and harvest were consistent for all individuals in model 1, which rendered it mathematically more tractable compared to the more complex, age-structured model 2 that separated the host population into juveniles and adults. We evaluated the interaction of ND transmission and harvest through changes in the basic reproduction number (R0) and short-term host population dynamics. Our findings demonstrated that ND introduction would likely provoke considerable disease-related mortality, up to 24% population decline in two years, but high harvest rates would dampen the magnitude of the outbreak. Model 2 produced moderate differences in disease dynamics compared to model 1 (R0 = 3.63 and 2.66, respectively), but highlighted the importance of adult disease dynamics in diminishing the epidemic potential. Therefore, we suggest that future studies should use a more realistic, age-structured model. Finally, for the presumptive risk that illegal trade of white-winged parakeets could introduce ND into wild populations, our results suggest that while high harvest rates may have a protective effect on the population by reducing virus transmission, the combined effects of high harvest and disease-induced mortality may threaten population survival. These results capture the complexity and consequences of the interaction between ND transmission and harvest in a wild parrot population and highlight the importance of preventing illegal trade

Estimating the Non-Monetary Burden of Neurocysticercosis in Mexico

Neurocysticercosis (NCC) is a major public health problem caused by the larvae of the parasite Taenia solium. The condition occurs when humans ingest eggs of the pork tapeworm Taenia solium, which then develop into larvae in the central nervous system. The disease is predominantly found and considered important in Latin American, Asian, and African countries and is associated with a large social and economic burden. Very few studies have been conducted to evaluate the burden of NCC and there are no estimates from Mexico. We estimated the disability adjusted life years (DALYs) lost due to NCC in Mexico incorporating morbidity and mortality due to NCC-associated epilepsy, and morbidity due to NCC-associated severe chronic headaches. NCC-associated epilepsy and severe chronic headaches were estimated to cause a loss of approximately 0.25 healthy year of life per 1,000 persons annually in Mexico. This is the first estimate of DALYs associated with NCC in Mexico. However, this value is likely to be underestimated since only the clinical manifestations of epilepsy and severe chronic headaches were included

Evolution of the Stx2-Encoding Prophage in Persistent Bovine Escherichia coli O157:H7 Strains

Escherichia coli O157:H7 is a human pathogen that resides asymptomatically in its bovine host. The level of Shiga toxin (Stx) produced is variable in bovine-derived strains in contrast to human isolates that mostly produce high levels of Stx. To understand the genetic basis for varied Stx production, chronological collections of bovine isolates from Wisconsin dairy farms, R and X, were analyzed for multilocus prophage polymorphisms, stx(2) subtypes, and the levels of stx(2) transcript and toxin. The E. coli O157:H7 that persisted on both farms were phylogenetically distinct and yet produced little to no Stx2 due to gene deletions in Stx2c-encoding prophage (farm R) or insertional inactivation of stx(2a) by IS1203v (farm X). Loss of key regulatory and lysis genes in Stx2c-encoding prophage abolished stx(2c) transcription and induction of the prophage and stx(2a)::IS1203v in Stx2a-encoding prophage generated a truncated stx(2a) mRNA without affecting phage production. Stx2-producing strains were transiently present (farm R) and became Stx2 negative on farm X (i.e., stx(2a)::IS1203v). To our knowledge, this is the first study that details the evolution of E. coli O157:H7 and its Stx2-encoding prophage in a chronological collection of natural isolates. The data suggest the bovine and farm environments can be niches where Stx2-negative E. coli O157:H7 emerge and persist, which explains the Stx variability in bovine isolates and may be part of an evolutionary step toward becoming bovine specialists