Cost-based optimization of the stopping threshold for local disease surveillance during progressive eradication of tuberculosis from New Zealand wildlife.

Bovine tuberculosis (TB) is managed in New Zealand largely via population reduction of the major wildlife disease reservoir of Mycobacterium bovis, the introduced brushtail possum Trichosurus vulpecula. New Zealand aims to eradicate M. bovis infection from its livestock and wildlife within 40 years, as the culmination of progressive regional eradication programmes. Declarations of regional eradication are decided after extensive possum population control and post-control surveillance; hence, we developed a modelling framework, based on eco-epidemiological simulation data, to provide cost-evaluated options for deciding when to make these declarations. A decision-support framework evaluated potential costs of wildlife surveillance (and recontrol, if required) with respect to the calculated probability of successful eradication of M. bovis from wildlife. This enabled expected costs to be predicted in terms of stopping thresholds, allowing selection of optimal stopping rules based on minimizing costs. We identified factors that could influence optimal stopping values applied during regional eradication. Where vector/disease surveillance was inexpensive (for example, using low-cost detection devices or sentinel wildlife hosts) optimization involved setting a higher rather than lower stopping value, as it would be cheaper to minimize the risk of making a false declaration of eradication than to remedy any such failure. In addition, any cost of recontrol would largely depend on the time to rediscovery of residual M. bovis infection in wildlife, which would in turn be linked to the level of ongoing passive surveillance (with more rapid detection of re-emergent infection among wildlife in farmland situations than in remote forested regions). These two scenarios would favour different optimal stopping rules, as would the consideration of stakeholder confidence and socio-political issues, which are discussed. The framework presented here provides guidance to assess the economics underlying eradication of bovine TB from New Zealand farming; this eliminates reliance upon a pre-determined and uniform stopping rule for ceasing active management.

Livestock as sentinels for an infectious disease in a sympatric or adjacent-living wildlife reservoir host.

A central question to address in managing wildlife diseases is how much effort and resources are required to reduce infection prevalence to below a requisite threshold? This requires surveillance for infection in at least one species involved in the infection cycle, a process that is often expensive and time-consuming but one which could be enhanced using additional sources of readily-obtainable surveillance data. We demonstrate how surveillance data from ruminant livestock monitored for bovine tuberculosis (bTB) in New Zealand can be employed in spatially-explicit modelling to help predict the probability of freedom from Mycobacterium bovis infection in a sympatric wildlife reservoir species, the brushtail possum (Trichosurus vulpecula). We apply the model to a case study and compare resulting probabilities of freedom when utilizing (1) livestock data only, (2) wildlife data only, and (3) combined livestock-plus-wildlife surveillance data. Results indicated that the greatest probability of M. bovis eradication was achieved using wildlife monitoring data supplemented with livestock surveillance data. This combined approach lessened the time required for a confident (95% probability) declaration of regional eradication. However, the combined model was sensitive to the precision of the input parameters, and we describe ways to account for this. In a broad sense, this modelling approach is flexible in that any spatial arrangement of wildlife habitat and farms can be analysed, provided infection is readily detectable in both the wild and domestic animal(s) of interest. It is applicable to monitoring any communicable wildlife disease that affects regularly-tested livestock. The potential benefits to wildlife disease management include reduced surveillance costs and more rapid achievement of targeted reductions in disease prevalence.

Inferential and forward projection modeling to evaluate options for controlling invasive mammals on islands.

Successful pest-mammal eradications from remote islands have resulted in important biodiversity benefits. Near-shore islands can also serve as refuges for native biota but require ongoing effort to maintain low-pest or pest-free status. Three management options are available in the presence of reinvasion risk: (1) control-to-zero density, in which immigration may occur but reinvaders are removed; (2) sustained population suppression (to relatively low numbers); or (3) no action. Biodiversity benefits can result from options one and two. The management challenge is to make evidence-based decisions on the selection of an appropriate objective and to identify a financially feasible control strategy that has a high probability of success. This requires understanding the pest species population dynamics and how it will respond to a range of potential management strategies, each with an associated financial cost. We developed a two-stage modeling approach that consisted of (1) Bayesian inferential modeling to estimate parameters for a model of pest population dynamics and control, and (2) a forward projection model to simulate a range of plausible management scenarios and quantify the probability of obtaining zero density within four years. We applied the model to an ongoing, six-year trapping program to control stoats (Mustela erminea) on Resolution Island, New Zealand. Zero density has not yet been achieved. Results demonstrate that management objectives were impeded by a combination of a highly fecund population, insufficient trap attractiveness, and a substantial proportion of the population that did not enter traps. Immigration is known to occur because the founding population arrived on the island by swimming from the mainland. However, immigration rate during this study was indistinguishable from zero. The forward projection modeling showed that control-to-zero density was feasible but required greater than a two-fold budget increase to intensify the trapping rate relative to population growth. The two-stage modeling provides the foundation for a management program in which broad-scale trials of additional trapping effort or improved trap lures would test model predictions and increase our understanding of system dynamics.

The influence of taste in willingness-to-pay valuations of sirloin steaks from postextraction algal residue-fed cattle.

Consumer preferences and willingness-to-pay (WTP) for beef sirloin steaks with differing production, physical, and credence attributes related to the use of postextraction algal residue (PEAR), a novel feed ingredient, were estimated. Ninety-six consumers participated in a sensory tasting panel before completing a choice set survey; 127 consumers completed only the choice set survey without sampling products. Steaks from grain- and PEAR-fed steers had similar Warner-Bratzler shear force (WBSF) scores (1.89 kg and 2.01 kg, respectively; = 0.77) and had lower WBSF scores than steaks from grass-fed steers (3.37 kg; < 0.05). Eicosapentaenoic acid (20:5) was not different among steaks from grain- and PEAR-fed steers ( = 0.39) but was greater compared with steaks from grass-fed cattle ( ≤ 0.03). Panelists in the sensory portion of the study evaluated beef samples for like/dislike of overall sample, overall flavor, beefy flavor, and juiciness. Panelist rating of overall like, overall flavor like, and beefy flavor like were not different between the PEAR- and grain-fed treatments ( > 0.26). Panelists rated the juiciness like/dislike of steaks from PEAR-fed cattle the highest ( < 0.01) among the 3 samples. Sensory tasting of the products was observed to alter the preferences of consumers. Consumers who completed only the survey negatively perceived beef from PEAR-fed cattle compared with beef from grain-fed cattle, with a WTP discount of -US$1.17/kg. However, with sensory tasting, the WTP for beef from PEAR-fed cattle was not discounted relative to beef from grain-fed cattle ( = 0.21). The nontasting consumers had much higher stated WTP values for credence attributes. Factors that influence the eating experience (tenderness and quality grade) dominated as the most important attributes on WTP among the tasting group. The use of no hormones and no antibiotics in production had a premium of $2.34/kg among the nontasting group, but with tasting, the premium was $1.19/kg. If PEAR-fed beef came to market, there would be no need to differentiate it from grain-fed beef unless retailers wanted to market it as a differentiated product. If it were marketed as a differentiated product, retailers would need to hold promotional tastings to change consumer's preconceived notions about the product.

Development of integrated surveillance systems for the management of tuberculosis in New Zealand wildlife.

Disease surveillance for the management of bovine tuberculosis (TB) in New Zealand has focussed, to a large extent, on the development of tools specific for monitoring Mycobacterium bovis infection in wildlife. Diagnostic techniques have been modified progressively over 30 years of surveillance of TB in wildlife, from initial characterisation of gross TB lesions in a variety of wildlife, through development of sensitive culture techniques to identify viable mycobacteria, to molecular identification of individual M. bovis strains. Of key importance in disease surveillance has been the elucidation of the roles that different wildlife species play in the transmission of infection, specifically defining brushtail possums (Trichosurus vulpecula) as true maintenance hosts compared to those that are predominantly spillover hosts, but which may serve as useful sentinel species to indicate TB persistence. Epidemiological modelling has played a major role in TB surveillance, initially providing the theoretical support for large-scale possum population control and setting targets at which control effort should be deployed to ensure disease eradication. As TB prevalence in livestock and wildlife declined throughout the 2000s, more varied field tools were developed to gather surveillance data from the diminishing possum populations, and to provide information on changing TB prevalence. Accordingly, ever more precise (but disparate) surveillance information began to be integrated into multi-faceted decision-assist models to support TB management decisions, particularly to provide informed parameters at which control effort could be halted, culminating in the Proof of Freedom modelling framework that now allows an area to be declared TB-free within chosen confidence limits. As New Zealand moves from large-scale TB control to regional eradication of disease in the coming years, further integrative models will need to be developed to support management decisions, based on combined field data of possum and TB prevalence, sentinel information, risk assessment in relation to financial benefits, and changing political and environmental needs.

A novel approach to assess the probability of disease eradication from a wild-animal reservoir host.

Surveying and declaring disease freedom in wildlife is difficult because information on population size and spatial distribution is often inadequate. We describe and demonstrate a novel spatial model of wildlife disease-surveillance data for predicting the probability of freedom of bovine tuberculosis (caused by Mycobacterium bovis) in New Zealand, in which the introduced brushtail possum (Trichosurus vulpecula) is the primary wildlife reservoir. Using parameters governing home-range size, probability of capture, probability of infection and spatial relative risks of infection we employed survey data on reservoir hosts and spillover sentinels to make inference on the probability of eradication. Our analysis revealed high sensitivity of model predictions to parameter values, which demonstrated important differences in the information contained in survey data of host-reservoir and spillover-sentinel species. The modelling can increase cost efficiency by reducing the likelihood of prematurely declaring success due to insufficient control, and avoiding unnecessary costs due to excessive control and monitoring.

High-throughput all-atom molecular dynamics simulations using distributed computing.

Although molecular dynamics simulation methods are useful in the modeling of macromolecular systems, they remain computationally expensive, with production work requiring costly high-performance computing (HPC) resources. We review recent innovations in accelerating molecular dynamics on graphics processing units (GPUs), and we describe GPUGRID, a volunteer computing project that uses the GPU resources of nondedicated desktop and workstation computers. In particular, we demonstrate the capability of simulating thousands of all-atom molecular trajectories generated at an average of 20 ns/day each (for systems of approximately 30 000-80 000 atoms). In conjunction with a potential of mean force (PMF) protocol for computing binding free energies, we demonstrate the use of GPUGRID in the computation of accurate binding affinities of the Src SH2 domain/pYEEI ligand complex by reconstructing the PMF over 373 umbrella sampling windows of 55 ns each (20.5 mus of total data). We obtain a standard free energy of binding of -8.7 +/- 0.4 kcal/mol within 0.7 kcal/mol from experimental results. This infrastructure will provide the basis for a robust system for high-throughput accurate binding affinity prediction.

Immigration policy, foreign agricultural labor, and exit intentions in the United States dairy industry.

United States agriculture is dependent on foreign labor. Current US immigration policies have been alleged to disrupt agricultural labor availability, particularly that of hired foreign labor. A national survey of dairy farmers across herd sizes and regions of the United States was conducted and the results were used to estimate the extent to which hired foreign labor dependency will affect exit intentions in dairy farming. This study found that the expected probability of exit from dairy farming increased as the use of hired foreign labor intensified. But the expected probability of exit also decreased rapidly as herd sizes got larger. Given the immigration policy currently in place, farmers expecting labor shortages in the future are expected to experience greater tendency to exit the industry.

Longitudinal study of MRS metabolites in Rasmussen encephalitis.

This study analyses the evolution of metabolite changes in an 8-year-old boy with focal Rasmussen encephalitis. Five MRI examinations, including magnetic resonance spectroscopy (MRS) were performed over 9 months. Following complex partial status, T2-weighted imaging showed transient dramatic signal increase in the left superior temporal gyrus and mesial temporal structures. Subsequent scans showed resolution of the swelling and signal normalization, with development of slight focal atrophy. MRS after status showed a reduction in N-acetylaspartate, total creatine and trimethylamines. Subsequent scans showed complete resolution of these metabolite abnormalities, followed later by development of further abnormal metabolite values. Lactate and glutamine/glutamate were elevated after status. After surgery, ex vivo high-field (1)H and (31)P MRS confirmed metabolite abnormalities (elevated choline and decreased aspartate, N-acetylaspartate, [(1)H]glutamate together with altered [(31)P]phospholipid ratios. These findings suggested active disease process in the anterior region of the excised superior temporal gyrus. We conclude that Rasmussen encephalitis is a combination of progressive encephalitic damage and fluctuating seizure effects, in which neuronal injury and recovery can occur. MRS measurements at a single time point should consider the fluctuating metabolite profile related to seizure activity.

Use of simulation mass balance modeling to estimate phosphorus and bacteria dynamics in watersheds.

Dynamic simulation technology is integrated with mass balance concepts and compartment-flux diagramming to create computer models that estimate contaminant export from watersheds over long and short-term futures under alternative simulated policies of watershed management. The Watershed Ecosystem Nutrient Dynamics (WEND) model, applied to developed watersheds with a mix of urban, agricultural, and forest land-uses, predicted phosphorus (P) export from three watersheds; a 275,000 ha dairy/urban watershed, a 77,000 ha poultry/urban watershed, and a 23,000 ha swine dominated watershed. Urban, agricultural, and forestry activities contribute to P export in different proportions. In all cases the P imports to the watershed exceed total export and P accumulates in watershed soils. Long-term future P export patterns are compared for several watershed management strategies that range from encouragement of rapid urban growth to aggressive environmental protection. The specific response of each watershed to imposed management is unique, but management strategies designed to reduce export of P over the long-term need to consider options that promote P input/output balance. Using this same approach, the Watershed Ecosystem Bacterial Dynamics (WEBD) model assesses the dynamics of bacterial populations in a small case-study watershed over an annual cycle as influenced by dairy farm management actions. WEND and WEBD models integrate the diversity of activities and stakeholders interested in the watershed and promote development of a more holistic understanding of watershed function. Model outputs are designed to assist watershed policy-makers, managers, and planners to explore potential future impacts of management/policy decisions.

Dynamic phosphorus mass balance modeling of large watersheds: long-term implications of management strategies.

The principles of mass balance, compartment-flux diagramming, and dynamic simulation modeling are integrated to create computer models that estimate phosphorus (P) export from large-scale watersheds over long-term futures. These Watershed Ecosystem Nutrient Dynamics (WEND) models are applied to a 275,000 ha dairy-documented watershed and a 77,000 ha poultry-dominated watershed in northeastern USA. Model predictions of present-day P export loads are consistent with monitoring data and estimates made using P export coefficients. For both watersheds P import exceeds P export and P is accumulating in the agricultural soils. Agricultural and urban activities are major contributors to P export from both watersheds. Continued urban growth will increase P export over time unless wastewater management is substantially enhanced and/or rates of urban growth are controlled. Agriculture cannot rely solely on the implementation of increasingly stringent conservation practices to reduce long-term P export but must consider options that promote P input/output balance. The WEND modeling process is a powerful tool to integrate the diversity of activities in watersheds into a holistic framework. Model outputs are suited to assist managers to explore long-term effects of overall watershed management strategies on P export in comparison to environmental and economic goals.

Orbital infarction and melting in a patient with systemic lupus erythematosus.

OBJECTIVE: To present a patient with systemic lupus erythematosus who developed infarction and melting of the orbit secondary to her systemic disease. DESIGN: A case report. PARTICIPANT: A 61-year-old white woman with a 5-year history of systemic lupus erythematosus. METHODS: The patient presented with left orbital pain, limitation of extraocular movements, and a fistula from the ethmoid sinus to the upper eyelid. A detailed examination with computerized tomography, ultrasound, and a comprehensive medical evaluation with laboratory testing was performed. Histopathologic analysis with special stains of the orbital tissues was also performed. RESULTS: Histopathologic examination of the biopsy specimens revealed the features of an inflammatory process involving the orbit, similar to a panniculitis. These include a lymphocytic reaction with a predominance of plasma cells, vasculitis with occlusion, and thickening of the vessel walls, necrosis, and hyalinization of fat. CONCLUSION: This is a unique case in which infarction and melting of the entire orbital structures occurred in the presence of systemic lupus erythematosus. The underlying disease process is a lupus-related panniculitis. The authors stress that this is a very rare entity and that other diseases should be ruled out before entertaining this diagnosis.

Associations between road traffic accidents and socio-economic deprivation on Scotland's west coast.

Road traffic accidents (RTAs) are declining, but remain a public health concern locally and world-wide. Scottish RTAs killed 316 people and injured over 20,000 in 1996. By 2020, they are predicted to become the world's third-leading cause of sickness and death. Little is know about associations between RTAs and deprivation; it has never been explored on Scotland's West Coast. This study analysed hospital A&E admissions and investigated associations between RTAs and socio-economic status. 1,300 attendance records at a 575-bed NHS Trust Accident & Emergency in North Lanarkshire were reviewed and 1,020 records analysed in conjunction with Health Board socio-economic data. Findings strongly suggest (p = 0.00461) a positive trend between RTA activity and deprivation. Significance held for gender, victim role, purpose of journey and age, except for drivers 60 and over. Given the preventative nature of RTAs and their contribution to morbidity and mortality, further research between RTAs and deprivation is suggested.

Adjuvants and immunostimulants for enhancing vaccine potency in fish.

Adjuvants combined with immunogens are effective enhancers of the immune response in fish. As in other animals, substances such as Freund's complete and incomplete adjuvants, light oils and bacterial lipopolysaccharides have been shown to induce elevated antibody production when added to bacterins and administered to fish. Light oil adjuvants are now used successfully with injectable bacterins of Aeromonas salmonicida, and in multivalent fish vaccines where A. salmonicida is combined with Yersinia sp., and/or Vibrio spp. antigen preparations. The oils are thought to act as depots or reservoirs, holding the antigens in globules at the site of injection, thus allowing prolonged dosage. Additions to the oils such as muramyl dipeptide, bacterial lipopolysaccharides and other bacterial and animal-extracted products may activate specific immune cell populations such as T-cells, neutrophils and other phagocytic cells important in the cellular mediated response. Conjugation of antigens with alum is another traditional approach which has been used for A. salmonicida and Y. ruckeri bacterins with varying results. The process enables antigen to be held in a reservoir and also may detoxify harmful substances. Recent research on substances such as beta-1,3 glucans, chitosan, levamisole, and other inflammatory agents shows enhancing effects on the specific immune response when added to immunogens and administered by injection, bath or by feeding. These substances may also act to elevate non-specific defence mechanisms against disease agents as most of them are active even when given alone.