The foot-and-mouth epidemic in Great Britain: pattern of spread and impact of interventions

We present an analysis of the current foot-and-mouth disease epidemic in Great Britain over the first 2 months of the spread of the virus. The net transmission potential of the pathogen and the increasing impact of control measures are estimated over the course of the epidemic to date. These results are used to parameterize a mathematical model of disease transmission that captures the differing spatial contact patterns between farms before and after the imposition of movement restrictions. The model is used to make predictions of future incidence and to simulate the impact of additional control strategies. Hastening the slaughter of animals with suspected infection is predicted to slow the epidemic, but more drastic action, such as "ring" culling or vaccination around infection foci, is necessary for more rapid control. Culling is predicted to be more effective than vaccination.     

Large-scale spatial-transmission models of infectious disease

During transmission of seasonal endemic diseases such as measles and influenza, spatial waves of infection have been observed between large distant populations. Also, during the initial stages of an outbreak of a new or reemerging pathogen, disease incidence tends to occur in spatial clusters, which makes containment possible if you can predict the subsequent spread of disease. Spatial models are being used with increasing frequency to help characterize these large-scale patterns and to evaluate the impact of interventions. Here, I review several recent studies on four diseases that show the benefits of different methodologies: measles (patch models), foot-and-mouth disease (distance-transmission models), pandemic influenza (multigroup models), and smallpox (network models). This review highlights the importance of the household in spatial studies of human diseases, such as smallpox and influenza. It also demonstrates the need to develop a simple model of household demographics, so that these large-scale models can be extended to the investigation of long-time scale human pathogens, such as tuberculosis and HIV.     

Emergence of drug-resistant influenza virus: population dynamical considerations

Given the considerable challenges to the rapid development of an effective vaccine against influenza, antiviral agents will play an important role as a first-line defense if a new pandemic occurs. The large-scale use of drugs for chemoprophylaxis and treatment will impose strong selection for the evolution of drug-resistant strains. The ensuing transmission of those strains could substantially limit the effectiveness of the drugs as a first-line defense. Summarizing recent data on the rate at which the treatment of influenza infection generates resistance de novo and on the transmission fitness of resistant virus, we discuss possible implications for the epidemiological spread of drug resistance in the context of an established population dynamic model.     

Evolution, safety, and highly pathogenic influenza viruses

Experience with influenza has shown that predictions of virus phenotype or fitness from nucleotide sequence are imperfect and that predicting the timing and course of evolution is extremely difficult. Such uncertainty means that the risk of experiments with mammalian-transmissible, possibly highly virulent influenza viruses remains high even if some aspects of their laboratory biology are reassuring; it also implies limitations on the ability of laboratory observations to guide interpretation of surveillance of strains in the field. Thus, we propose that future experiments with virulent pathogens whose accidental or deliberate release could lead to extensive spread in human populations should be limited by explicit risk-benefit considerations.     

猪流行性感冒的简易识别与防控

猪流行性感冒是由猪A型流行感冒病毒引起的一种急性高度接触性传染病。以猪的发病突然,传播迅速,来势迅猛,群体发病,发病率高,致死率低为特征。临床上主要表现为高热、咳嗽、呼吸困难、喘息等上呼吸道感染的症候群。影响着猪的生存、繁殖和育肥,并对人流感的发病也起着一定的作用,因而受到社会各界的广泛关注。目前,对猪流行性感冒防控措施仍不完善,全国各地时有暴发流行。因此,积极防控猪流感的发生任重道远,需要全社会力量共同参与,分工协作完成这项攻坚战。就猪流行性感冒的发病特点和防控措施作一简单的综述。     

禽流感与人类健康

禽流感(avian influenza,AI)是由A型流感病毒(avian influenza virus)引起的一种禽类感染征或疾病综合症,高致病性禽流感(highly pathogenic avian influenza,HPAI)可引起禽类100％的死亡。由于抗原转变和抗原漂移,禽流感病毒是高度可变的。人禽流感是指高致病性禽流感病毒跨越物种界限,引起人类感染的一种新发传染病。目前,全球已发现H5N1、H7N7、H9N2等亚型禽流感病毒可感染人类。但目前还没有发现禽流感病毒具有在人群中相互传播的能力。对禽流感必须采用积极的预防策略。在加强监测的基础上,对家禽采用扑杀和免疫相结合的措施,可以有效地控制禽流感的流行。研制人类流感疫苗,是预防新的流感病毒株的流行的可靠保证。     

A two-amino acid change in the hemagglutinin of the 1918 influenza virus abolishes transmission

The 1918 influenza pandemic was a catastrophic series of virus outbreaks that spread across the globe. Here, we show that only a modest change in the 1918 influenza hemagglutinin receptor binding site alters the transmissibility of this pandemic virus. Two amino acid mutations that cause a switch in receptor binding preference from the human alpha-2,6 to the avian alpha-2,3 sialic acid resulted in a virus incapable of respiratory droplet transmission between ferrets but that maintained its lethality and replication efficiency in the upper respiratory tract. Furthermore, poor transmission of a 1918 virus with dual alpha-2,6 and alpha-2,3 specificity suggests that a predominant human alpha-2,6 sialic acid binding preference is essential for optimal transmission of this pandemic virus. These findings confirm an essential role of hemagglutinin receptor specificity for the transmission of influenza viruses among mammals.     

桔潜蛾及其天敌的生态位

通过调查福建农业大学生产处柑桔园桔潜蛾 Ｐｈｙｌｌｏｃｎｉｓｔｉｓ ｃｉｔｒｅｌｌａ Ｓｔａｉｎｔｏｎ 及其天敌的分布情况,测定其时间和空间生态位宽度、重叠和相似性比例,分析了桔潜蛾与其天敌空间上的同域性和时间上的同步性,即时间和空间上的“跟随”作用．寄生性天敌群子强于捕食性天敌群子,表明在自然环境中寄生性天敌群子对桔潜蛾的控制作用强;捕食性天敌小花蝽 Ｏｒｉｕｓ ｓａｕｔｅｒｉ虽然食谱生态位宽,但生态位重叠却小,说明这种天敌尽管分布广泛,可在时间和空间上没能有效“跟随”害虫的发生,对害虫控制作用不大;寄生性天敌短腹桔啮小蜂 Ｃｉｔｒｏｓｔｉｃｈｕｓ ｐｈｙｌｌｏｃｎｉｓｔｏｉｄｅｓ （ Ｎａｒａｙａｎａｎ）与桔潜蛾在时间上的同步性和空间上的同域性均优于其它天敌,为优势天敌,应加以保护和利用     

Are we ready for pandemic influenza?

During the past year, the public has become keenly aware of the threat of emerging infectious diseases with the global spread of severe acute respiratory syndrome (SARS), the continuing threat of bioterrorism, the proliferation of West Nile virus, and the discovery of human cases of monkeypox in the United States. At the same time, an old foe has again raised its head, reminding us that our worst nightmare may not be a new one. In 2003, highly pathogenic strains of avian influenza virus, including the H5N1 and H7N7 subtypes, again crossed from birds to humans and caused fatal disease. Direct avian-to-human influenza transmission was unknown before 1997. Have we responded to these threats by better preparing for emerging disease agents, or are we continuing to act only as crises arise? Here we consider progress to date in preparedness for an influenza pandemic and review what remains to be done. We conclude by prioritizing the remaining needs and exploring the reasons for our current lack of preparedness for an influenza pandemic.     

高氏瘤粉虱及其天敌的生态位

通过对高氏瘤粉虱及其天敌时间生态位和空间生态位的调查，测定了生态位宽度、重叠和比例相似性，在此基础上，构建时空二维生态位，并分析了高氏瘤粉虱及其天敌空间上的同域性和时间上的同步性，即时间和空间上的“跟随”作用。结果表明：在自然环境中寄生性天敌对高氏瘤粉虱的控制作用强；捕食性天敌对高氏瘤粉虱控制作用不大；害生性天敌桨角蚜小蜂与高氏瘤粉虱在时间上的同步性和空间上的同域性均优于其它天敌，为优势天敌，应加以保护和利用。     

2009甲型H1N1流感病毒的研究综述

2009年4月初,出现1种新型甲型（H1N1）流感病毒,并通过人—人传播蔓延全球,文章介绍了该病毒的分类与宿主范围,并对其病毒学及分子特征进行了概述,最后指出加强对猪群中流行的流感病毒监管的必要性及研制通用疫苗的重要性。     

Spatial-Temporal Changes in Grain Production,Consumption and Driving Mechanism in China

The spatial-temporal patterns of grain production and consumption have an important influence on the effective national grain supply on condition of tight balance in the total grain amount in China. In this paper, we analyze the spatial-temporal patterns of grain production, consumption and the driving mechanism for their evolution processes in China. The results indicate that both gravity centers of grain production and consumption in China moved toward the northern and eastern regions, almost in the same direction. The coordination of grain production and consumption increased slightly from 1995 to 2007 but decreased from 2000 to 2007. There is a spatial difference between the major districts of output increase and the strong growth potential in grain consumption, which indicates an increasing difficulty in improving the regional coordination of grain production and consumption. The movement of the gravity center of grain production is significantly correlated with regional differences in grain production policy, different economic development models, and spatial disparity of land and water resource use. For grain consumption, the main driving factors include rapid urbanization, the upgrade of food consumption structure, and distribution of food industries.     

猪流感病毒研究进展

猪流感是猪常见呼吸道疾病之一,在世界范围内流行.患猪常续发其他疫病,导致猪死亡率增加,该病毒变异体还可跨种传播,严重影响养猪业的发展及人的健康.为此,简要介绍了猪流感的病原,比较了猪流感临床症状,分析了病毒跨种间传播致病机制的分子基础,并概述了其公共卫生意义.     

The spatial dimension in population fluctuations

Theoretical research into the dynamics of coupled populations has suggested a rich ensemble of spatial structures that are created and maintained either by external disturbances or self-reinforcing interactions among the populations. Long-term data of the Canadian lynx from eight Canadian provinces display large-scale spatial synchrony in population fluctuations. The synchronous dynamics are not time-invariant, however, as pairs of populations that are initially in step may drift out of phase and back into phase. These observations are in agreement with predictions of a spatially-linked population model and support contemporary population ecology theory.     

2009甲型H1N1流感病毒的研究综述(英文)

[目的]介绍2009甲型H1N1流感病毒的研究进展。[方法]从病毒的分类与宿主,病毒学,分子特征及疫苗等方面简要介绍了2009甲型H1N1流感病毒。[结果]2009年4月初出现的一种新型甲型(H1N1)流感病毒通过人-人传播迅速蔓延全球,该病毒包含一组新的基因片段,已知的最接近的前体为在猪体内发现的病毒。该病毒似乎保留着重新感染猪的潜力从而可能继续与猪源病毒发生重组。所有已注册的2009甲型流感疫苗均在对志愿者的临床试验中测试了安全性和免疫原性,发现所有疫苗都是安全的,并且单剂量的疫苗给药后引起保护性抗体反应。[结论]为进一步研究2009甲型H1N1流感病毒提供依据。     

H5亚型禽流感研究势态——基于Citespace的文献计量分析

为准确把握H5亚型禽流感的研究进展，本研究基于CNKI文献数据库中的393篇文献和Web of Science(WOS)文献数据库中的1 560篇文献为研究样本，通过信息可视化技术对2个数据库中的文献样本的发文国家、文献数量、高频被引文献、高频关键词、主要发表作者和机构等进行分析。结果表明:1)国际上中国和美国在该领域的研究较多，两国发文量占比可达56.80%；每年文献数量与禽流感疫情的严重程度密切相关。与CNKI文献样本相比，WOS文献样本的文献数量、高频被引文献的被引频次更具有优势，并且WOS文献样本中发文机构之间和发文作者之间的合作更密切。2)高频被引文献和高频关键词在一定程度上反映了该领域的研究热点，主要包括野鸟导致H5亚型禽流感病毒的传播和进化；H5亚型禽流感的流行病学、致病机制和免疫疗法；重组疫苗、灭活疫苗和基于血凝素HA的广谱疫苗等新型疫苗研发；H5亚型禽流感病毒突发的防控措施等内容。本研究认为在未来疫情的长期监测与预测、病毒的快速检测技术和新型疫苗的开发等仍是研究热点，为H5亚型禽流感领域工作者提供参考价值。     

Airborne transmission of influenza A/H5N1 virus between ferrets

Highly pathogenic avian influenza A/H5N1 virus can cause morbidity and mortality in humans but thus far has not acquired the ability to be transmitted by aerosol or respiratory droplet ("airborne transmission") between humans. To address the concern that the virus could acquire this ability under natural conditions, we genetically modified A/H5N1 virus by site-directed mutagenesis and subsequent serial passage in ferrets. The genetically modified A/H5N1 virus acquired mutations during passage in ferrets, ultimately becoming airborne transmissible in ferrets. None of the recipient ferrets died after airborne infection with the mutant A/H5N1 viruses. Four amino acid substitutions in the host receptor-binding protein hemagglutinin, and one in the polymerase complex protein basic polymerase 2, were consistently present in airborne-transmitted viruses. The transmissible viruses were sensitive to the antiviral drug oseltamivir and reacted well with antisera raised against H5 influenza vaccine strains. Thus, avian A/H5N1 influenza viruses can acquire the capacity for airborne transmission between mammals without recombination in an intermediate host and therefore constitute a risk for human pandemic influenza.     

The pulvinar regulates information transmission between cortical areas based on attention demands

Selective attention mechanisms route behaviorally relevant information through large-scale cortical networks. Although evidence suggests that populations of cortical neurons synchronize their activity to preferentially transmit information about attentional priorities, it is unclear how cortical synchrony across a network is accomplished. Based on its anatomical connectivity with the cortex, we hypothesized that the pulvinar, a thalamic nucleus, regulates cortical synchrony. We mapped pulvino-cortical networks within the visual system, using diffusion tensor imaging, and simultaneously recorded spikes and field potentials from these interconnected network sites in monkeys performing a visuospatial attention task. The pulvinar synchronized activity between interconnected cortical areas according to attentional allocation, suggesting a critical role for the thalamus not only in attentional selection but more generally in regulating information transmission across the visual cortex.     

中国对非洲农产品出口贸易的空间格局及影响因素

为探究中国对非洲农产品出口贸易的发展规律,基于UNCOMTRADE统计数据,采用空间分析法、引力模型,对其空间格局演变及影响因素两个方面进行研究,结果表明:非洲已成为中国农产品出口贸易的稳定区域;中国对非洲全域及其五大子区域的农产品出口贸易多元化指数及均衡度指数呈现稳定增长的发展态势;中国对非洲农产品贸易出口在空间上呈现出较弱的正相关关系,西部非洲的贝宁、多哥和加纳三国成为主要的高—高集聚区;GDP总量越高、与中国首都距离越远、人均耕地面积差异越大的非洲国家对中国的农产品出口具有越强的吸引力。     

Large trench-parallel gravity variations predict seismogenic behavior in subduction zones

We demonstrate that great earthquakes occur predominantly in regions with a strongly negative trench-parallel gravity anomaly (TPGA), whereas regions with strongly positive TPGA are relatively aseismic. These observations suggest that, over time scales up to at least 1 million years, spatial variations of seismogenic behavior within a given subduction zone are stationary and linked to the geological structure of the fore-arc. The correlations we observe are consistent with a model in which spatial variations in frictional properties on the plate interface control trench-parellel variations in fore-arc topography, gravity, and seismogenic behavior.