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Paratuberculosis or Johne’s disease (JD), is a chronic infectious disease causing intractable diarrhea in cattle, which leads to less productivity, such as decreased milk yield, and lower daily weight gain. As a control measure against JD in cattle, national serological surveillance has been conducted in Japan since 1998. To conduct modeling studies that are useful to evaluate the effectiveness of control measures against JD, reliable parameter values, such as length of time from infection to the start of fecal shedding or antibody expression, are especially important. These parameters in the Japanese cattle population are assumed to be different from those in other countries with a higher prevalence of JD or in experimental infection settings; therefore, they must be estimated for the cattle population in Japan. Data from national surveillance conducted in Tokachi District, Hokkaido Prefecture, were used for this study. Using data from JD diagnostic tests for all cattle in Tokachi District between 1998 and 2014, all testing histories for infected animals were estimated as the number of tested cattle and positive cattle at each age of month for both fecal and antibody tests. A deterministic mathematical model for JD development, from infection to fecal shedding and antibody expression in infected cattle, was constructed to obtain the probability of testing positive when applied to both fecal and antibody tests at a given age. Likelihood was obtained from these estimated test results and best values for parameters were obtained using the Markov Chain Monte-Carlo method. Fifty-five percent of infected cattle were projected to have a transient shedding period, which was estimated to start 12 months after infection and last for 4 months. Persistent shedding was projected to occur in all infected cattle, and estimated to begin 7–84 months from infection. Following persistent shedding, antibody expression was estimated to start 7 months later. These values are useful for developing models to evaluate the status of JD infection and the effectiveness of control measures in the Japanese cattle population. [ABSTRACT FROM AUTHOR]

This review addresses the survival and persistence ofMycobacterium aviumsubsp.paratuberculosis(MAP), the causative pathogen of Johne’s disease (JD), once it has left its ruminant host. JD has significant economic impact on dairy, beef and sheep industries and is difficult to control due to the long-term sub-clinical nature of the infection, intermittent or persistent MAP shedding during and after this period, inadequate test effectiveness, and the potential for MAP to exist for extended periods outside the host. The role that environmental factors play in the persistence and spread of MAP and consequent disease is assessed. Published risk factor analysis, organism survival across various environmental media and conditions, presence and spread in ruminant and non-ruminant wildlife, and the general potential for survival and multiplication of MAP ex-host both on and off-farm are discussed and knowledge gaps highlighted. An inclusive approach to disease management that takes into account the persistence and transport of the causative organism in on-farm soils and waters, land use and management, dispersal by domestic and non-domestic host species, as well as general animal husbandry is required on those farms where more traditional approaches to disease management have failed to reduce disease prevalence. [ABSTRACT FROM PUBLISHER]

The objective of this study was to evaluate the performance of bacterial culture of feces and serum ELISA to correctly identify cows with Mycobacterium avium ssp. paratuberculosis (MAP) at heavy, light, and non-fecal-shedding levels. A total of 29,785 parallel test results from bacterial culture of feces and serum ELISA were collected from 17 dairy herds in Minnesota, Pennsylvania, and Colorado. Samples were obtained from adult cows from dairy herds enrolled for up to 10 yr in the National Johne's Disease Demonstration Herd Project. A Bayesian latent class model was fitted to estimate the probabilities that bacterial culture of feces (using 72-h sedimentation or 30-min centrifugation methods) and serum ELISA results correctly identified cows as high positive, low positive, or negative given that cows were heavy, light, and non-shedders, respectively. The model assumed that no gold standard test was available and conditional independency existed between diagnostic tests. The estimated conditional probabilities that bacterial culture of feces correctly identified heavy shedders, light shedders, and non-shedders were 70.9, 32.0, and 98.5%, respectively. The same values for the serum ELISA were 60.6, 18.7, and 99.5%, respectively. Differences in diagnostic test performance were observed among states. These results improve the interpretation of results from bacterial culture of feces and serum ELISA for detection of MAP and MAP antibody (respectively), which can support on-farm infection control decisions and can be used to evaluate disease-testing strategies, taking into account the accuracy of these tests. [ABSTRACT FROM AUTHOR]

Our objectives were to evaluate the effects of transportation and lairage on fecal shedding of Escherichia coli 0157 {E. coli 0157), total Escherichia coli, and total coliforms in feedlot cattle, and the rela-tionships between E. coli 0157 prevalence and total E. coli population. The study was a randomized complete block design with a split-plot including 2 treatments: a nontransported group, which remained in its pen at all times, and a transported group, which was transported for 1 h in a trailer and subsequently unloaded in a differ-ent pen. The experiment was repeated on 3 different days (blocking factor) with 20 steers/d (10 steers/treatment, 60 total). Fecal samples were taken pretransport (h 0) and after 4 and 28 h, lairage from freshly voided fecal pats were taken from each animal. One gram of feces was transferred to a PBS tube, serially diluted, and plated onto Petrifilm for enumeration of total coliforms. Another sample (1 g) was added to gram-negative broth contain-ing Cefixime, cefsulodin, and vancomycin, and subjected to immunomagnetic separation. Resulting beads were plated onto MacConkey agar with sorbitol, Cefixime, and tellurite. Nonsorbitol fermenting colonies were selected and tested for indole production and Ol 57 antigen agglu-tination. Results were confirmed using an API 20E kit. Prevalence of E. coli 0157 was transient across blocks. E. coli 0157 prevalence revealed no treatment x sam-pling time interaction (P = 0.179) or sampling time effect (P = 0.937), but a tendency for a treatment effect (P = 0.092). Numbers of E. coli and other coliforms did not change across blocks. No effect of treatment (P > 0.7) was observed on total E. coli concentrations or total coli-forms. However, tendencies for treatment x sampling time interactions were observed on both populations (P < 0.08), as well as a tendency for a sampling time effect on total E. coli (P = 0.087) and an effect on total coliforms (P = 0.004). Prevalence of E. coli 0157 was not correlated with the concentration of total E. coli (P = 0.954). Results suggest that shedding of E. coli 0157 and eolifonns can vary within a period of 29 h. Greater statis-tical power and pathogen quantification, as well as hide sampling and stress-related measurements, are needed to be able to conclude on the effects of transport stress on E. coli 0157 prevalence and the changes undergone in pathogen shedding patterns after transportation. [ABSTRACT FROM AUTHOR]

Distillers grains (DG), a co-product of ethanol production used as protein and energy supplements in cattle diets, have been shown to increase fecal shedding of Escherichia coli 0157:H7, a major foodbome pathogen. The reason for the positive association is not known. Because DG often replaces grain in the diet, decreased starch content and flow to the hindgut may create a favorable environment for E. coli 0157:H7. Our objective was to detennine whether the addition of starch to a corn DG-supplemented diet negates the effects of DG on fecal shedding of E. coli 0157:H7. We conducted a study with 21 steers fed 1 of 3 diets: a corn grain-based basal diet (CON), basal diet supplemented with 25% com dried DG (DDG), and basal diet supplemented with 25%o DDG with com starch (DDG+S) added at a level intended to increase starch concentration to that of the CON diet. Steers, housed individually in a biosafety level 2 animal facility, were randomly allocated to treatment diets and orally inoculated with a 5-strain mixture (109 cfu per steer) of nalidixic acid-resistant (NalR) E. coli 0157:H7. Fecal samples were collected for 5 wk, and on d 35, steers were euthanized and necropsied to collect gut content samples. Fecal or gut samples were cultured to determine prevalence and concentrations of NalR E. coli 0157:H7. Dietary starch concentrations, based on feed analysis, were 46.3% in the CON compared with 43.3 and 41.3% in the DDG and DDG+S diets, respectively. Steers fed DDG or DDG+S diets shed NalR E. coli 0157:H7 more often (P = 0.0027 and 0.0003, respectively) and at greater concentrations (1.9 or 2.0 cfu/g; P = 0.0025 and 0.0006) than those fed CON diet (1.4 cfu/g), but no difference was observed between DDG and DDG+S diets. Cumulative prevalence and concentrations of NalR E. coli 0157:H7 were greater in gut samples collected at necropsy in steers fed DDG and DDG+S diets compared with those fed CON diet, but no difference was observed between DDG and DDG+S diets. The lack of effect of starch addition to the DDG diet on fecal shedding of E. coli 0157:H7 may be because either the decreased starch content in the DG-supplemented diet is not a factor in the increased shedding of E. coli 0157:H7 or inclusion of pure starch in the diet may not have achieved our intended goal to have starch flow into the hindgut similar to that of com grain. The study confirms our previous finding of the positive association between feeding DG and fecal shedding of E. coli 0157:H7. [ABSTRACT FROM AUTHOR]

Hindgut is a major colonization site for Escherichia coli O157 in cattle. In this study, diets were formulated to effect changes in hindgut fermentation to test our hypothesis that changes in the hindgut ecosystem could have an impact on fecal shedding of E. coli O157. Feedlot heifers (n = 347) were prescreened for the prevalence of E. coli O157 by fecal and rectoanal mucosal swab cultures. A subset of 40 heifers identified as being positive for fecal shedding of E. coli O157 was selected, housed in individual pens, and randomly allocated to 4 dietary treatments. Treatments were arranged as a 2 x 2 factorial, with factor 1 consisting of grain type (sorghum or wheat) and factor 2 being method of grain processing (steam-flaking or dry-rolling). Four transition diets, each fed for 4 d, were used to adapt the animals to final diets that contained 93% concentrate and 7% roughage. The grain fraction consisted of dry-rolled sorghum, steam-flaked sorghum, a mixture of dry-rolled wheat and steam-flaked corn, or a mixture of steam-flaked wheat and steam-flaked corn. Wheat diets contained 52% wheat and 31% steam-flaked corn (DM basis). Fecal and rectoanal mucosal swab samples were obtained 3 times a week to isolate (enrichment, immunomagenetic separation, and plating on selective medium) and identify (sorbitol negative, indole production, and agglutination test) E. coli O157. The data were analyzed as repeated measures of binomial response (positive or negative) on each sampling day. Method of processing (dry-rolled vs. steam-flaked), sampling day, and the grain type x day interaction were significant (P < 0.05), but not the method of processing x grain type interaction. The average prevalence of E. coli O157 from d 9 was greater (P < 0.001) in cattle fed steam-flaked grains (65%) compared with those fed dry- rolled grains (30%). Average prevalence in cattle fed sorghum (51%) or wheat (43%) were similar (P> 0.10) on most sampling days. Results from this study indicate that feeding dry-rolled grains compared with steam-flaked grains reduced fecal shedding of E. coli O157. Possibly, dry-rolling allowed more substrate to reach the hindgut where it was fermented, thus making the hindgut inhospitable to the survival of E. coli O157. Dietary intervention to influence hindgut fermentation offers a simple and practical mitigation strategy to reduce the prevalence of E. coli O157 in feedlot cattle. [ABSTRACT FROM AUTHOR]