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Vaccination appears to have beneficial effects regarding infection and death caused by WNV.

Mycobacterium avium subspecies paratuberculosis is the causative agent of Johne's disease, a chronic enteritis in ruminants including cattle, sheep, goats, and farmed deer. Recently, this bacterium has received an increasingly wide interest because of a rapidly growing body of scientific evidence which suggests that human infection with this microorganism may be causing some, and possibly all, cases of Crohn's disease. Recent studies have shown that a high percentage of people with Crohn's disease are infected with M. avium subsp. paratuberculosis; whether the association of this bacterium and Crohn's disease is causal or coincidental is not known. Crohn's disease is a gastrointestinal disease in humans with similar histopathological findings to those observed in the paucibacillary form of Johne's disease in cattle. The search for risk factors in Crohn's disease has been frustrating. However, epidemiologists have gathered enough information that points to an association between M. avium subsp. paratuberculosis and Crohn's disease. This paper reviews epidemiological models of disease causation, the major philosophical doctrines about causation, the established epidemiological criteria for causation, and the currently known epidemiological evidence of M. avium subsp. paratuberculosis as a possible cause of Crohn's disease.

SYNOPSISObjective. We identified the risk factors associated with the anthrax outbreak of 2005 in animals in North Dakota.Methods. Medical records of the 2005 anthrax outbreak were obtained from the Veterinary Diagnostic Laboratory at North Dakota State University. Additional data were obtained from the North Dakota state veterinarian's office, and supplemental questionnaires were administered to producers. The data obtained included ecological and environmental factors, animal health factors, and management factors.Results. Anthrax occurred from July 1 to October 12, 2005. The cases were located in eastern North Dakota around the Red River Basin. Ransom, LaMoure, and Barnes counties reported most cases (71%). Species affected included cattle, bison, horses, sheep, elk, deer, pigs, and llamas. The predominant symptom was sudden death (38%) followed by bleeding from orifices (17%). Chi-square analysis indicated significant differences between case and control premises on the following variables: death reported on neighboring pasture, vaccination period, dry conditions, wet conditions, antibiotic use, multiple vaccination, and type of predator (coyote). Factors that significantly (p,0.05) predicted anthrax occurrences on the final logistic regression model were vaccination, use of antibiotics during an outbreak, and period of vaccine administration (before or during the outbreak).Conclusions. The characteristics of the anthrax outbreak regarding time and place of occurrence, animals affected, clinical signs reported, and mortality rate were consistent with previous reports of natural anthrax outbreaks in animals. A number of factors that significantly predicted anthrax occurrence in animals in the 2005 outbreak in North Dakota were identified. This information is important in planning appropriate control and prevention measures for anthrax, including recommending the right vaccination and treatment regimens in managing future anthrax outbreaks.

The objective was to describe variability in prevalence, incidence, and duration of fecal shedding of naturally occurring E. coli O157:H7 by a group of feedlot cattle over time. One hundred steers, randomly assigned to 10 pens, were fed a high-concentrate finishing diet for 136 days (19 weeks). Rectal feces from each animal were tested for E. coli O157:H7 every week for 19 weeks. E. coli O157:H7 was recovered from each animal that completed the study and was detected from at least one animal every week. Average pen prevalence of cattle shedding E. coli O157:H7 varied significantly over time (P < 0.0001) and across pens (P < 0.0001), ranging from 1 to 80%. Pairwise comparisons of mean pen prevalence of E. coli O157:H7 between weeks and estimation of the predicted probability of an incident case of E. coli O157:H7 over time allowed the definition of three distinct phases--namely, the preepidemic, epidemic, and postepidemic periods. Average pen prevalence varied significantly over time (P < 0.01) and across pens (P < 0.001) for all time periods. The odds of an incident case were significantly greater during epidemic and postepidemic periods relative to the preepidemic period (P = 0.0002 and P = 0.03, respectively). Duration of infection was significantly longer for first or second infections that began during epidemic or postepidemic periods relative to the preepidemic period (P < 0.001). Both incidence and duration of shedding peaked during the epidemic period. Pen-level prevalence of cattle shedding E. coli O157:H7 was affected by both incidence and duration of shedding and could be explained by time- or pen-dependent risk factors, or both.