Yrjö T. Gröhn

Risk factors for post partum ovarian dysfunction in high producing dairy cows in Belgium: A field study

An epidemiological study of risk factors for postpartal ovarian disturbances was carried out on 334 high-yielding dairy cows in 6 well-managed Belgian herds. Ovarian activity was closely monitored using progesterone profiles, based on twice weekly RIA-analysis for progesterone in milk fat, starting at 10 d after calving and continuing until the confirmation of a new pregnancy. Attention was focused on abnormal cyclicity during the preservice, postpartum period; cows were divided into 6 different categories. Three of these categories (normal profile, delayed cyclicity, and prolonged luteal phase) were of major importance and were analyzed using a multiple variable logistic regression model. Season of calving (stable vs pasture, odds ratio (OR)=5.7), an extended length of the previous dry period (> 77 vs < or = 63 d, OR=2.9), problem calvings (OR=3.6), abnormal vaginal discharge (OR=4.5), health problems during the first month of lactation (clinical disease, OR=5.4; ketosis, OR=11.3), and clinical parameters illustrating the appearance of a severe negative energy balance significantly increased the risk for delayed cyclicity before service. Parity (> or = 4 vs 1, OR=2.5), problem calvings (OR=2.9), occurrence of puerperal disturbances (OR ranged from 3.5 to 11.0), health problems during the first month of lactation (OR=3.1), and an early resumption of ovarian cyclicity after calving (< 19 d vs > 32 d, OR=2.8) increased the risk for prolonged luteal cycles before service.

Landscape and Meteorological Factors Affecting Prevalence of Three Food-Borne Pathogens in Fruit and Vegetable Farms

ABSTRACT Produce-related outbreaks have been traced back to the preharvest environment. A longitudinal study was conducted on five farms in New York State to characterize the prevalence, persistence, and diversity of food-borne pathogens in fresh produce fields and to determine landscape and meteorological factors that predict their presence. Produce fields were sampled four times per year for 2 years. A total of 588 samples were analyzed for Listeria monocytogenes, Salmonella, and Shiga toxin-producing Escherichia coli (STEC). The prevalence measures of L. monocytogenes, Salmonella, and STEC were 15.0, 4.6, and 2.7%, respectively. L. monocytogenes and Salmonella were detected more frequently in water samples, while STEC was detected with equal frequency across all sample types (soil, water, feces, and drag swabs). L. monocytogenes sigB gene allelic types 57, 58, and 61 and Salmonella enterica serovar Cerro were repeatedly isolated from water samples. Soil available water storage (AWS), temperature, and proximity to three land cover classes (water, roads and urban development, and pasture/hay grass) influenced the likelihood of detecting L. monocytogenes. Drainage class, AWS, and precipitation were identified as important factors in Salmonella detection. This information was used in a geographic information system framework to hypothesize locations of environmental reservoirs where the prevalence of food-borne pathogens may be elevated. The map indicated that not all croplands are equally likely to contain environmental reservoirs of L. monocytogenes. These findings advance recommendations to minimize the risk of preharvest contamination by enhancing models of the environmental constraints on the survival and persistence of food-borne pathogens in fields.

Effect of parity on periparturient neutrophil function in dairy cows

Impairment of periparturient neutrophil function in dairy cows has been described. This may contribute to increased susceptibility of cows to bacterial infections during the periparturient period. Susceptibility to many complications of the postpartum period is influenced by parity. The aim of this experiment was to determine whether parity influenced periparturient neutrophil function in Holstein cows. Cows (n = 46, of which 26 were calving for the first, second or third time, and 20 were of more advanced parity) were sampled during the last prepartum week, the first postpartum week, 3 weeks postpartum and 6 weeks postpartum. Neutrophils were isolated by centrifugation and hypotonic lysis of erythrocytes. Neutrophil superoxide anion production was determined by the superoxide dismutase inhibitable reduction of ferricytochrome c, and stimulus-induced shape change was determined at 0, 30, 60 and 120 s after exposure to zymosan activated bovine plasma. Superoxide anion production was significantly depressed in the first postpartum week in all cows. At this time, superoxide anion production was significantly lower in cows in their fourth or greater lactation than in cows in the first three lactations. Neutrophil shape change responsiveness was also influenced by parity; immediately prepartum, the shape change responsiveness differed between groups at 120 s after application of the stimulus, and during the first postpartum week shape change responsiveness was less in cows of advanced parity at 30, 60 and 120 s after application of the stimulus. We concluded that cows in the fourth or greater lactation suffered more profound periparturient impairment of neutrophil function than younger cows and that this may be a factor mediating their increased susceptibility to some postpartum complications.

Risk factors associated with Salmonella and Listeria monocytogenes contamination of produce fields.

ABSTRACT Identification of management practices associated with preharvest pathogen contamination of produce fields is crucial to the development of effective Good Agricultural Practices (GAPs). A cross-sectional study was conducted to (i) determine management practices associated with a Salmonella- or Listeria monocytogenes-positive field and (ii) quantify the frequency of these pathogens in irrigation and nonirrigation water sources. Over 5 weeks, 21 produce farms in New York State were visited. Field-level management practices were recorded for 263 fields, and 600 environmental samples (soil, drag swab, and water) were collected and analyzed for Salmonella and L. monocytogenes. Management practices were evaluated for their association with the presence of a pathogen-positive field. Salmonella and L. monocytogenes were detected in 6.1% and 17.5% of fields (n = 263) and 11% and 30% of water samples (n = 74), respectively. The majority of pathogen-positive water samples were from nonirrigation surface water sources. Multivariate analysis showed that manure application within a year increased the odds of a Salmonella-positive field (odds ratio [OR], 16.7), while the presence of a buffer zone had a protective effect (OR, 0.1). Irrigation (within 3 days of sample collection) (OR, 6.0), reported wildlife observation (within 3 days of sample collection) (OR, 6.1), and soil cultivation (within 7 days of sample collection) (OR, 2.9) all increased the likelihood of an L. monocytogenes-positive field. Our findings provide new data that will assist growers with science-based evaluation of their current GAPs and implementation of preventive controls that reduce the risk of preharvest contamination.

Epidemiological Model for Clostridium difficile Transmission in Healthcare Settings

OBJECTIVE Recent outbreaks of Clostridium difficile infection (CDI) have been difficult to control, and data indicate that the importance of different sources of transmission may have changed. Our objectives were to evaluate the contributions of asymptomatic and symptomatic C. difficile carriers to new colonizations and to determine the most important epidemiological factors influencing C. difficile transmission. DESIGN, SETTING, AND PATIENTS Retrospective cohort study of all patients admitted to medical wards at a large tertiary care hospital in the United States in the calendar year 2008. METHODS Data from six medical wards and published literature were used to develop a compartmental model of C. difficile transmission. Patients could be in one of five transition states in the model: resistant to colonization (R), susceptible to colonization (S), asymptomatically colonized without protection against CDI (C(-)), asymptomatically colonized with protection against CDI (C(+)), and diseased (ie, with CDI; D). RESULTS The contributions of C(-), C(+), and D patients to new colonizations were similar. The simulated basic reproduction number ranged from 0.55 to 1.99, with a median of 1.04. These values suggest that transmission within the ward alone from patients with CDI cannot sustain new C. difficile colonizations and therefore that the admission of colonized patients plays an important role in sustaining transmission in the ward. The epidemiological parameters that ranked as the most influential were the proportion of admitted C(-) patients and the transmission coefficient for asymptomatic carriers. CONCLUSION Our study underscores the need to further evaluate the role of asymptomatically colonized patients in C. difficile transmission in healthcare settings.

Microarray Identification of Clostridium difficile Core Components and Divergent Regions Associated with Host Origin

Clostridium difficile is a gram-positive, spore-forming enteric anaerobe which can infect humans and a wide variety of animal species. Recently, the incidence and severity of human C. difficile infection has markedly increased. In this study, we evaluated the genomic content of 73 C. difficile strains isolated from humans, horses, cattle, and pigs by comparative genomic hybridization with microarrays containing coding sequences from C. difficile strains 630 and QCD-32g58. The sequenced genome of C. difficile strain 630 was used as a reference to define a candidate core genome of C. difficile and to explore correlations between host origins and genetic diversity. Approximately 16% of the genes in strain 630 were highly conserved among all strains, representing the core complement of functional genes defining C. difficile. Absent or divergent genes in the tested strains were distributed across the entire C. difficile 630 genome and across all the predicted functional categories. Interestingly, certain genes were conserved among strains from a specific host species, but divergent in isolates with other host origins. This information provides insight into the genomic changes which might contribute to host adaptation. Due to a high degree of divergence among C. difficile strains, a core gene list from this study offers the first step toward the construction of diagnostic arrays for C. difficile.

The cost and management of different types of clinical mastitis in dairy cows estimated by dynamic programming

The objective of this study was to estimate the cost of 3 different types of clinical mastitis (CM) (caused by gram-positive bacteria, gram-negative bacteria, and other organisms) at the individual cow level and thereby identify the economically optimal management decision for each type of mastitis. We made modifications to an existing dynamic optimization and simulation model, studying the effects of various factors (incidence of CM, milk loss, pregnancy rate, and treatment cost) on the cost of different types of CM. The average costs per case (US

Analysis of correlated continuous repeated observations: modelling the effect of ketosis on milk yield in dairy cows

) of gram-positive, gram-negative, and other CM were

Quantitative risk assessment for Listeria monocytogenes in selected categories of deli meats: impact of lactate and diacetate on listeriosis cases and deaths.

133.73,

The Cost and Benefit of Listeria Monocytogenes Food Safety Measures

211.03, and