A Simulation Study of the Use of Vaccination to Control Foot-and-Mouth Disease Outbreaks Across Australia.

This study examines the potential for foot-and-mouth disease (FMD) control strategies that incorporate vaccination to manage FMD spread for a range of incursion scenarios across Australia. Stakeholder consultation was used to formulate control strategies and incursion scenarios to ensure relevance to the diverse range of Australian livestock production regions and management systems. The Australian Animal Disease Spread model (AADIS) was used to compare nine control strategies for 13 incursion scenarios, including seven control strategies incorporating vaccination. The control strategies with vaccination differed in terms of their approaches for targeting areas and species. These strategies are compared with two benchmark strategies based on stamping out only. Outbreak size and duration were compared in terms of the total number of infected premises, the duration of the control stage of an FMD outbreak, and the number of vaccinated animals. The three key findings from this analysis are as follows: (1) smaller outbreaks can be effectively managed by stamping out without vaccination, (2) the size and duration of larger outbreaks can be significantly reduced when vaccination is used, and (3) different vaccination strategies produced similar reductions in the size and duration of an outbreak, but the number of animals vaccinated varied. Under current international standards for regaining FMD-free status, vaccinated animals need to be removed from the population at the end of the outbreak to minimize trade impacts. We have shown that selective, targeted vaccination strategies could achieve effective FMD control while significantly reducing the number of animals vaccinated.

Optimal surveillance against foot-and-mouth disease: A sample average approximation approach.

Decisions surrounding the presence of infectious diseases are typically made in the face of considerable uncertainty. However, the development of models to guide these decisions has been substantially constrained by computational difficulty. This paper focuses on the case of finding the optimal level of surveillance against a highly infectious animal disease where time, space and randomness are fully considered. We apply the Sample Average Approximation approach to solve our problem, and to control model dimension, we propose the use of an infection tree model, in combination with sensible 'tree-pruning' and parallel processing techniques. Our proposed model and techniques are generally applicable to a number of disease types, but we demonstrate the approach by solving for optimal surveillance levels against foot-and-mouth disease using bulk milk testing as an active surveillance protocol, during an epidemic, among 42,279 farms, fully characterised by their location, livestock type and size, in the state of Victoria, Australia.

Pressure Injury Risk Factors in Critical Care Patients: A Descriptive Analysis.

BACKGROUND: Pressure injury (PI) development in the critical care population is multifactorial. Despite the application of evidence-based prevention strategies, PIs do occur and may be unavoidable in some patients. OBJECTIVES: To describe the risk factors associated with PI development in a sample of medical-surgical intensive care unit patients and determine whether these risk factors were congruent with the risk factors proposed in the work of the National Pressure Ulcer Advisory Panel on unavoidable PIs. METHODS: A retrospective, descriptive design was used to determine the PI risk factors present in a sample of 57 critically ill patients admitted to the medical-surgical intensive care unit for more than 24 hours and who acquired a PI during their admission. RESULTS: The most frequently identified risk factors were immobility (n = 57 [100%]), septic shock (n = 31 [54%]), vasopressor use (n = 37 [65%]), head-of-bed elevation greater than 30° (n = 53 [93%]), sedation (n = 50 [87.7%]), and mechanical ventilation for more than 72 hours (n = 46 [81%]). The most common PI location was the sacrum (n = 32 [56%]), and the most common stage reported was deep-tissue PI (n = 39 [68%]). The mean number of days to PI development was reported at 7.5 (SD, 7.2) days. CONCLUSIONS: Results of this descriptive study were congruent with the literature surrounding the clinical situations that predispose patients to unavoidable PIs. While the implementation of aggressive PI prevention strategies is essential to reducing PI rates, it is important to recognize that in certain populations, such as the critically ill, exposure to certain risk factors may potentially escalate PI risk beyond the scope of prevention and result in an unavoidable PI. Recognizing these risk factors is significant in the journey to differentiate PIs that result from a lack of preventive care from those that may be prevention immune.

Early Decision Indicators for Foot-and-Mouth Disease Outbreaks in Non-Endemic Countries.

Disease managers face many challenges when deciding on the most effective control strategy to manage an outbreak of foot-and-mouth disease (FMD). Decisions have to be made under conditions of uncertainty and where the situation is continually evolving. In addition, resources for control are often limited. A modeling study was carried out to identify characteristics measurable during the early phase of a FMD outbreak that might be useful as predictors of the total number of infected places, outbreak duration, and the total area under control (AUC). The study involved two modeling platforms in two countries (Australia and New Zealand) and encompassed a large number of incursion scenarios. Linear regression, classification and regression tree, and boosted regression tree analyses were used to quantify the predictive value of a set of parameters on three outcome variables of interest: the total number of infected places, outbreak duration, and the total AUC. The number of infected premises (IPs), number of pending culls, AUC, estimated dissemination ratio, and cattle density around the index herd at days 7, 14, and 21 following first detection were associated with each of the outcome variables. Regression models for the size of the AUC had the highest predictive value (R2 = 0.51-0.9) followed by the number of IPs (R2 = 0.3-0.75) and outbreak duration (R2 = 0.28-0.57). Predictability improved at later time points in the outbreak. Predictive regression models using various cut-points at day 14 to define small and large outbreaks had positive predictive values of 0.85-0.98 and negative predictive values of 0.52-0.91, with 79-97% of outbreaks correctly classified. On the strict assumption that each of the simulation models used in this study provide a realistic indication of the spread of FMD in animal populations. Our conclusion is that relatively simple metrics available early in a control program can be used to indicate the likely magnitude of an FMD outbreak under Australian and New Zealand conditions.

Vasopressors and development of pressure ulcers in adult critical care patients.

BACKGROUND: Vasopressors are lifesaving agents used to raise mean arterial pressure in critically ill patients in shock states. The pharmacodynamics of these agents suggest vasopressors may play a role in development of pressure ulcers; however, this aspect has been understudied. OBJECTIVE: To examine associations between type, dose, and duration of vasopressors (norepinephrine, epinephrine, vasopressin, phenylephrine, dopamine) and development of pressure ulcers in medical-surgical and cardiothoracic intensive care unit patients and to examine predictors of the development of pressure ulcers in these patients. METHODS: A retrospective correlational design was used in a sample of 306 medical-surgical and cardiothoracic intensive care unit patients who received vasopressor agents during 2012. RESULTS: Norepinephrine and vasopressin were significantly associated with development of pressure ulcers; vasopressin was the only significant predictor in multivariate analysis. In addition, mean arterial pressure less than 60 mm Hg in patients receiving vasopressors, cardiac arrest, and mechanical ventilation longer than 72 hours were predictive of development of pressure ulcers. Patients with a cardiac diagnosis at the time of admission to the intensive care unit were less likely than patients without such a diagnosis to experience pressure ulcers while in the unit. CONCLUSION: The addition of vasopressin administered concomitantly with a first-line agent (often norepinephrine) may represent the point at which the risk for pressure ulcers escalates and may be an early warning to heighten strategies to prevent pressure ulcers. Conversely, because vasopressors cannot be terminated to avert development of pressure ulcers, these findings may add to the body of knowledge on factors that potentially contribute to the development of unavoidable pressure ulcers.

Assessing the risk of highly pathogenic avian influenza H5N1 transmission through poultry movements in Bali, Indonesia.

Indonesia continues to report the highest number of human and poultry cases of highly pathogenic avian influenza H5N1. The disease is considered to be endemic on the island of Bali. Live bird markets are integral in the poultry supply chain on Bali and are important, nutritionally and culturally, for the rural and urban human populations. Due to the lack of biosecurity practiced along the supply chain from producer to live bird markets, there is a need to understand the risks associated with the spread of H5N1 through live bird movements for effective control. Resources to control H5N1 in Indonesia are very limited and cost effective strategies are needed. We assessed the probability a live bird market is infected through live poultry movements and assessed the effects of implementing two simple and low cost control measures on this risk. Results suggest there is a high risk a live bird market is infected (0.78), and risk mitigation strategies such as detecting and removing infected poultry from markets reduce this risk somewhat (range 0.67-0.76). The study demonstrates the key role live poultry movements play in transmitting H5N1 and the need to implement a variety of control measures to reduce disease spread.

Critical care physicians: attitudes, beliefs, and knowledge about pressure ulcers.

OBJECTIVE: The objective of this study was to determine critical care physicians' attitudes, beliefs, and knowledge toward pressure ulcer (PrU) prevention and treatment in critical care patients. DESIGN: Descriptive, correlational PARTICIPANTS: 56 critical care physicians MAIN OUTCOME MEASURES: Survey instrument developed to collect demographic information and information regarding attitudes and beliefs about PrUs and PrU knowledge. RESULTS: The majority of physicians (69%) reported poor to adequate basic medical education training on PrU prevention and treatment. Sixty percent reported never attending a PrU lecture. Most physicians reported their role to be important to very important in the areas of PrU prevention (71.4%) and treatment (67.9%). Physicians' perceived knowledge regarding PrU prevention and treatment was most frequently reported as adequate (48%) and poor (37%). The mean score on the knowledge test was 18.1 (range, 12-24; SD, 2.26), equating to a percentage score of 75%. No significant relationship was found between physicians' perceived PrU knowledge and actual knowledge score. CONCLUSIONS: Prevalence rates of acquired PrUs in critical care adult patients are cited as the highest among hospitalized patients; thus, critical care physicians encounter patients at risk for or with PrUs regularly in clinical practice. Management of a critically ill patient requires a cohesive, multidisciplinary approach, including prevention and/or management of PrUs. The critical care physician, as a vital member of this team, may benefit from PrU education in an effort to heighten awareness of this phenomenon in critical care patients.

The human and animal health impacts of introduction and spread of an exotic strain of West Nile virus in Australia.

Vector-borne diseases can have substantial impacts on human and animal health, including major epidemics. West Nile virus (WNV) is of particular international importance due to its recent emergence and impact in the Western Hemisphere. Despite the presence of a sub-type of WNV (Kunjin virus, KUN) in Australia, a potential ecological niche could be occupied by an exotic strain of WNV of the North American type. This study assesses the probability an exotic strain of WNV enters Australia via an infected mosquito in an aircraft from the United States (U.S.) landing at Sydney airport, the probability it spreads to susceptible species and the impact of the resulting outbreak on human and animal health. A release, exposure and consequence assessment were conducted using expert opinion and scientific literature to parameterise the inputs for the models (OIE, 2009). Following establishment of WNV in Australia, the spatio-temporal spread of WNV was predicted over a six year period based on the Australian human and equine populations at-risk, the known distribution of other mosquito-borne flaviviruses in Australia, climatic factors, and the spread of WNV in the U.S. following it's incursion in New York City in 1999. The impact of this spread was measured as a multiplier of human and equine demographics using the U.S. incidence and case fatality rates as a reference. For an 8 month period from September to April (considering seasonal impact on mosquito activity during the coldest months in Australia and the U.S.), and assuming WNV is endemic in the U.S., the median probability an infected mosquito is introduced is 0.17, and the median number of infected mosquitoes introduced is predicted to be zero, with a 95th percentile range of one. The overall probability of a WNV outbreak (WNV released into Australia, susceptible hosts exposed and the virus spread) occurring in the human and the horse population during this time period is estimated to be 7.0×10(-6) and 3.9×10(-6), respectively. These values are largely influenced by the presence of mosquitoes in aircrafts and whether the introduced infected mosquito contacts wild birds. Results of this study suggest there is a low risk of introduction and spread of an exotic strain of WNV from the U.S via aircraft, and provides an insight into the magnitude and impact of the spread among human and horse populations. The generic framework presented could be applied to assess the potential introduction of other mosquito-borne diseases (which involve a wild bird transmission cycle) via international aircraft movements.

The effects of various instructional methods on retention of knowledge about pressure ulcers among critical care and medical-surgical nurses.

BACKGROUND: To determine whether there was a difference in retention of knowledge about pressure ulcers with a traditional lecture versus computer-based instruction. METHODS: A quasi-experimental, pretest/posttest design was used. Medical-surgical and critical care nurses (N = 60) were randomly assigned to a lecture, to computer-based instruction, or to a control group. Study participants were given the pressure ulcer knowledge test before and immediately after the program and at 3-month and 6-month intervals. RESULTS: Analysis of variance showed statistically significant differences in pretest and posttest scores [F(2, 57) = 35.784, p = .000] and in posttest to 3-month scores [F(2, 57) = 18.427, p = .000] among the three groups. CONCLUSION: The most significant loss of pressure ulcer knowledge, regardless of educational method, occurred within the first 3 months. Based on these findings, quarterly education in pressure ulcer prevention is recommended to maintain knowledge. Computer-based instruction is a viable option for acquisition and retention of knowledge about pressure ulcer prevention.