The Influence of Meteorology on the Spread of Influenza: Survival Analysis of an Equine Influenza (A/H3N8) Outbreak

The influences of relative humidity and ambient temperature on the transmission of influenza A viruses have recently been established under controlled laboratory conditions. The interplay of meteorological factors during an actual influenza epidemic is less clear, and research into the contribution of wind to epidemic spread is scarce. By applying geostatistics and survival analysis to data from a large outbreak of equine influenza (A/H3N8), we quantified the association between hazard of infection and air temperature, relative humidity, rainfall, and wind velocity, whilst controlling for premises-level covariates. The pattern of disease spread in space and time was described using extraction mapping and instantaneous hazard curves. Meteorological conditions at each premises location were estimated by kriging daily meteorological data and analysed as time-lagged time-varying predictors using generalised Cox regression. Meteorological covariates time-lagged by three days were strongly associated with hazard of influenza infection, corresponding closely with the incubation period of equine influenza. Hazard of equine influenza infection was higher when relative humidity was <60% and lowest on days when daily maximum air temperature was 20–25°C. Wind speeds >30 km hour−1 from the direction of nearby infected premises were associated with increased hazard of infection. Through combining detailed influenza outbreak and meteorological data, we provide empirical evidence for the underlying environmental mechanisms that influenced the local spread of an outbreak of influenza A. Our analysis supports, and extends, the findings of studies into influenza A transmission conducted under laboratory conditions. The relationships described are of direct importance for managing disease risk during influenza outbreaks in horses, and more generally, advance our understanding of the transmission of influenza A viruses under field conditions

Independence of extent of tortuosity and calcification in iliac arteries

Abstract not availableNicholas Dowson, Benjamin Thurston, Prue Cowled, Margaret Boult, Robert Fitridg

Low total psoas area as scored in the clinic setting independently predicts midterm mortality after endovascular aneurysm repair in male patients

Preoperative sarcopenia is an established risk factor for poor outcomes after surgery. Methods for assessing sarcopenia are either complex, time consuming, or poorly validated. We aimed to assess the interobserver reliability of scoring psoas area at the level of the L3 vertebra and to evaluate whether sarcopenia scored by this simple and rapid method correlated with other fitness scoring methods or impacted on mortality and duration of stay for patients undergoing endovascular aneurysm repair (EVAR).We had access to 191 preoperative computed tomography scans of patients who underwent EVAR. For each scan the axial slice at the most caudal level of the L3 vertebra was extracted. Three observers independently calculated the combined cross-sectional area of the left and right psoas muscle at this level. Interobserver variability was calculated as per Band and Altman. Psoas area was normalized for patient height with sarcopenia defined as total psoas area of <500 mm(2)/m(2). The effect of sarcopenia on patient survival was assessed using Cox proportional hazards models. Kaplan-Meier curves are also presented.Interobserver reliability of scoring psoas area was acceptable (reproducibility coefficient as percent of mean for each observer pair: 7.92%, 7.95%, and 14.33%). Sarcopenic patients had poorer survival (hazard ratio, 2.37; P = .011) and an increased hospital duration of stay (4.0 days vs 3.0 days; P = .008) when compared with nonsarcopenic patients. Sarcopenic patients were more likely to self-report as unfit (12.4% vs 33.3%; P = .004). Sarcopenia did not correlate with an increased rate of postprocedure complications.Psoas area scoring has good interobserver reliability. Preoperative sarcopenia as defined by psoas area was associated with poorer survival and of longer length of stay. As all patients being worked up for an endovascular aortic aneurysm repair will undergo a computed tomography scan, this method is a rapid and effective way to highlight patients in the clinic setting who have an increased risk of morbidity and mortality after EVAR.Benjamin Thurston, Guilherme N. Pena, Stuart Howell, Prue Cowled and Robert Fitridg

Evaluating the effectiveness of the response to equine influenza in the Australian outbreak and the potential role of early vaccination

Objective  To use modelling and epidemiological analyses to assess the effectiveness of control strategies employed during the equine influenza outbreak and determine if early vaccination might have had a beneficial effect. Methods  Transmission of infection was modelled using stochastic, spatial simulation, based on data from 16 regions in New South Wales and Queensland over the first month of the outbreak. Results  The model accurately represented the spread of infection in both space and time and showed that vaccination strategies would have reduced new infections by ∼60% and reduced the size of the infected area by 8–9%, compared to the non-vaccination baseline. Conclusion  When used in conjunction with biosecurity measures and movement controls, early vaccination could play an important role in the containment and eradication of equine influenza

A novel-molecular ecology approach to ascertaining emigration/immigration and potential disease spread in feral pigs

Our study used two consecutive years of aerial culling then molecular ecology techniques (microsatellite analysis) to obtain parentage data from a widely dispersed and low density feral pig population during drought conditions in the semi-arid rangelands of Australia. This data was analysed geo-spatially to provide estimates on the actual minimum movements of feral pigs. The aim of this exercise was to obtain data that could be used to improve models that investigate rates of disease spread. The derived data revealed that some individuals will move much greater distances than previously recorded. The maximum recorded movement was 143km between a boar and pregnant sow in less than 1 year, with the mean boar to successfully mated sow distance being 43km. Thus, home ranges in this situation could be assumed to be much larger than previously calculated. Movement models were developed from this data and were based upon three assumptions of home range affinity; fixed home range, moving home range and no home range. Mean daily movements generated were 3km linear distance away from a previous mating for boars. Models revealed that currently planned disease eradication zones for Australia may be inadequate if an exotic disease outbreak remains undetected for only a short period of time (1 week). Using previously generated deterministic models for foot–and-mouth disease spread, and this data to alter home range size, the threshold population density below which disease will not transmit declines markedly

Evaluating the effectiveness of early vaccination in the control and eradication of equine influenza-A modelling approach

In August 2007, Australia which had previously been free of equine influenza, experienced a large outbreak that lasted approximately 4 months before it was eradicated. The outbreak required a significant national response by government and the horse industries. The main components of the response were movement controls, biosecurity measures, risk-based zoning and, subsequently, vaccination to contain the outbreak. Although not initially used, vaccination became a key element in the eradication program, with approximately 140 000 horses vaccinated. Vaccination is recognised as a valuable tool for managing El in endemically infected countries but there is little experience using it in situations where the objective is disease eradication. Vaccination was undoubtedly an important factor in 2007 as it enabled movements of some horses and associated industry activities to recommence. However, its contribution to containment and eradication is less clear. A premises-level equine influenza model, based on an epidemiological analysis of the 2007 outbreak, was developed to evaluate effectiveness of the mitigation strategies used and to investigate whether vaccination, if applied earlier, would have had an effect on the course of the outbreak. The results indicate that early use of strategic vaccination could have significantly reduced the size of the outbreak. The four vaccination strategies evaluated had, by 1 month into the control program, reduced the number of new infections on average by 60% and the size of the infected area by 8-9%. If resources are limited, a 1 km suppressive ring vaccination around infected premises gave the best results, but with greater vaccination capacity, a 3 km ring vaccination was the most effective strategy. The findings suggest that as well as reducing clinical and economic impacts, vaccination when used with biosecurity measures and movement controls could play an important role in the containment and eradication of equine influenza. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved

Quantitative analysis of animal-welfare outcomes in helicopter shooting: a case study with feral dromedary camels (Camelus dromedarius)

Context Helicopter shooting is a common and effective tool for reducing overabundant wildlife populations. However, there is little quantitative information on the humaneness of the method, leading to uncertainty in wildlife-management policy. There is, subsequently, a need for an improved understanding of the welfare implications of helicopter shooting. Aim A study was undertaken to infer the humaneness of helicopter shooting for a case study species, the feral dromedary camel (Camelus dromedarius). Methods Seven post-mortem studies (n≤715) and one ante-mortem study (n≤192) were undertaken during routine helicopter shooting programs of free-ranging camels. In these studies, we measured four animal-welfare parameters to allow inference on the humaneness of the technique. These parameters were time to death, instantaneous death rate (proportion of animals for which time to death≤0), wounding rate and location of bullet-wound tract. We also modelled these welfare variables against hypothesised explanatory variables to assist improvement of future programs. Key results The mean wounding rate was 0.4%, and the killing efficacy of the technique was 99.6%. Mean time to death was 4s, and mean instantaneous death rate was 83%. Each animal displayed a mean 2.4 bullet-wound tracts, with 75%, 63% and 35% of animals shot at least once in the thorax, cranium and cervical spine, respectively. Regression analysis revealed that the identity of the shooter and the nature of the local vegetation were the most important factors associated with an animal experiencing an inferred instantaneous death or not. Conclusions Helicopter shooting of feral camels produces a very low wounding rate and rapid time to death. Shooter identity is the most important consideration for determining animal-welfare outcomes. Improvements to the humaneness of programs can be made by increasing the rigour of shooter selection and training. Implications Wildlife killing methods must be demonstrated to be humane to receive public support; however, few shooting methods are objectively examined. Helicopter shooting can be independently examined and operators assessed. Adoption of this examination template may allow continual improvement by industry as well as increasing societal acceptance of helicopter shooting

The human growth arrest-specific gene Gas1 maps outside the candidate region of the gene for nevoid basal cell carcinoma syndrome

Wicking, C ; Breen, M ; Negus, K ; Berkman, J ; Evdokiou, A ; Cowled, P ; Chenevix-trench, G ; Wainwrigh