Infectious animal disease and its control

The control of infectious diseases in the main food-producing animals is considered and the main factors involved in the epizootiology of disease are presented. The properties of infectious agents and their natural history together with factors that influence the spread and development of disease are summarized. The factors in intensive animal husbandry that affect the occurrence of infectious disease and its control are considered. These include population density, population movement, management, hygiene and genetic constitution of the host. They encourage the appearance of new diseases, changes in the character of established diseases and the development of pathogenicity in infectious agents that were previously of no importance. Intensive animal husbandry has also increased the importance of multifactorial disease, which includes diseases that require more than one infectious agent or one or more infectious agents plus other factors for their cause. The methods of control of infectious disease currently available are described and the success and difficulties of their control on a global, national and local (farm or enterprise) basis are considered. Examples of diseases of global importance where national and world programmes of control and eradication have been of varying success are described. Examples of diseases that are enzootic throughout the world and the procedures used for their control are also described. The technological opportunities for the improvement of the control of infectious disease in the future are discussed. It is considered that developments in molecular biology and immunology will provide improvements in diagnostic tools and will revolutionize the development of animal resistance to disease and the production and use of vaccines.     

Mapping of alterations in noninfectious proviruses of spleen necrosis virus.

Ten recombinant lambda phage containing proviruses of spleen necrosis virus (SNV) were previously obtained. Six of the proviruses are infectious and four are not infectious in infectious DNA assays. In this paper, we show that these noninfectious proviruses are not infectious because of alterations in the viral DNA. We constructed recombinants between infectious and noninfectious proviruses and tested these recombinants in an infectious DNA assay. In addition, we carried out cotransfection of a noninfectious provirus with a restriction endonuclease-generated fragment of viral DNA. The alterations in the viral DNA resulting in lack of infectivity were mapped to regions of viral DNA of 1 to 2 kilobase pairs. These results and other biochemical data indicate that alterations in retrovirus proviruses occur at a high frequency.     

Differential biophysical properties of infectious intracellular and secreted hepatitis C virus particles

The recent development of a cell culture infection model for hepatitis C virus (HCV) permits the production of infectious particles in vitro. In this report, we demonstrate that infectious particles are present both within the infected cells and in the supernatant. Kinetic analysis indicates that intracellular particles constitute precursors of the secreted infectious virus. Ultracentrifugation analyses indicate that intracellular infectious viral particles are similar in size (approximately 65 to 70 nm) but different in buoyant density (approximately 1.15 to 1.20 g/ml) from extracellular particles (approximately 1.03 to 1.16 g/ml). These results indicate that infectious HCV particles are assembled intracellularly and that their biochemical composition is altered during viral egress.     

剑阁县2001-2010年法定传染病流行特征及防治对策分析

目的：通过分析10年法定传染病疫情的流行趋势和三间分布特征,为制定传染病预防控制策略和措施提供依据。方法：采用描述性流行病学方法分析疫情趋势和三间分布情况,数据资料用SPSS10．0和Excel2003进行统计分析。结果：2001～2010年共报告乙、丙类传染病25种26129例,年均发病率386．89／10万,年均死亡率0．15／10万,10年间报告法定传染病以血源及性传播传染病和呼吸道传染病为主,居第1位的是血源及性传播传染病,共报告5种12453例,占53．03％;其次是呼吸道传染病,共报告5种9828例,占41．85％,近3年发病居于各类传染病首位;第三位的是肠道传染病,共报5种1149例,占4．89％。发病居前5位的传染为乙肝、肺结核、流行性腮腺炎、痢疾、麻疹,主要传染病以乙肝、肺结核为主,近年性传播疾病呈快速增长趋势。结论：血源及性传播传染病和呼吸道传染病是今后重点防控传染病。     

剑阁县2001～2010 年法定传染病流行特征及防治对策分析

目的:通过分析10年法定传染病疲情的流行趋势和三间分布特征,为制定传染病预防控制策略和措施提供依据.方法:采用描述性流行病学方法分析疫情趋势和三间分布情况,数据资料用SPSS10.0和Excel 2003进行统计分析.结果:2001～2010年共报告乙、丙类传染病25种26 129例,年均发病率386.89/10万,年均死亡率0.15/10万,10年间报告法定传染病以血源及性传播传染病和呼吸道传染病为主,居第1位的是血源及性传播传染病,共报告5种12 453例,占53.03％;其次是呼吸道传染病,共报告5种9828例,占41.85％,近3年发病居于各类传染病首位;第三位的是肠道传染病,共报5种1149例,占4.89％.发病居前5位的传染为乙肝、肺结核、流行性腮腺炎、痢疾、麻疹,主要传染病以乙肝、肺结核为主,近年性传播疾病呈快速增长趋势.结论:血源及性传播传染病和呼吸道传染病是今后重点防控传染病.     

环境水体中肠道感染菌群与几种典型致病菌的QPCR检测及相关性分析

利用定量PCR(QPCR)方法,对环境水体中的肠道感染菌群及几种致病菌进行4个月的连续检测。结果表明:在污染严重的水体中,埃希氏大肠菌(E.coli)是水中肠道感染菌群的主体,其强度接近于用通用引物检测出的肠道感染菌群强度。当肠道感染菌群拷贝数超过10⁴copies·100 mL^-1时,沙门氏菌(S.typhrmurium)和志贺氏痢疾杆菌(Shigella flexneri)也持续被检出,可以认为是水体病原污染的标志之一;在轻度污染和清洁水体中,当肠道感染菌群拷贝数低于10⁴copies·100 mL^-1时,通过通用引物检测到的肠道感染菌群主要是上述3种病原细菌以外的细菌,且3种病原细菌的出现频度和强度与肠道感染菌群之间没有明显的相关性。     

Are there Characteristics of Infectious Diseases that Raise Special Ethical Issues?1

This paper examines the characteristics of infectious diseases that raise special medical and social ethical issues, and explores ways of integrating both current bioethical and classical public health ethics concerns. Many of the ethical issues raised by infectious diseases are related to these diseases' powerful ability to engender fear in individuals and panic in populations. We address the association of some infectious diseases with high morbidity and mortality rates, the sense that infectious diseases are caused by invasion or attack on humans by foreign micro-organisms, the acute onset and rapid course of many infectious diseases, and, in particular, the communicability of infectious diseases. The individual fear and community panic associated with infectious diseases often leads to rapid, emotionally driven decision making about public health policies needed to protect the community that may be in conflict with current bioethical principles regarding the care of individual patients. The discussion includes recent examples where dialogue between public health practitioners and medical-ethicists has helped resolve ethical issues that require us to consider the infected patient as both a victim with individual needs and rights and as a potential vector of disease that is of concern to the community.     

Infectious morbidity in the USSR: its structure, levels, dynamics and economic significance

Taking well-grounded strategic decisions on the control of infectious diseases requires the knowledge of modern epidemiological situation with respect to the total infectious pathology. The structure, levels and dynamics of morbidity in infectious diseases, registered according to Form No. 85 (Infection), on the territory of the USSR are considered. Besides, the evaluation of the economic damage inflicted to the national economy of the USSR by infectious morbidity is presented.     

浅谈医院传染病信息网络直报管理工作

目的为进一步加强医院传染病管理,评价干预措施对降低医院传染病疫情报告迟报率、漏报率的效果,提出合理化建议。方法回顾性分析医院疫情网络直报的问题,比较采取干预措施前后的传染病报告及时率、漏报率,找出影响网络直报工作质量及影响传染病疫情报告及时率、漏报率的因素,探讨提高传染病监测质量的应对对策。结果网络直报的目的不明确,漏报、迟报仍然存在,各种填写不规范及网络直报系统运行是影响网络直报的主要因素。结论采取有效的干预措施能有效地降低医院传染病疫情报告的迟报率、漏报率。从多方面不断完善疾病监测体系,提高疫情报告工作的质量。     

From Pasteur to genomics: progress and challenges in infectious diseases

Over the past decade, microbiology and infectious disease research have undergone the most profound revolution since the times of Pasteur. Genomic sequencing has revealed the much-awaited blueprint of most pathogens. Screening blood for the nucleic acids of infectious agents has blunted the spread of pathogens by transfusion, the field of antiviral therapeutics has exploded and technologies for the development of novel and safer vaccines have become available. The quantum jump in our ability to detect, prevent and treat infectious diseases resulting from improved technologies and genomics was moderated during this period by the greatest emergence of new infectious agents ever recorded and a worrisome increase in resistance to existing therapies. Dozens of new infectious diseases are expected to emerge in the coming decades. Controlling these diseases will require a better understanding of the worldwide threat and economic burden of infectious diseases and a global agenda.     

气候变化对传染病爆发流行的影响研究进展

全球气候变化已影响到传染病发生、传播与变化的各个环节,从病原体及其携带者、传播途径和人体自身抵抗力等方面直接或间接影响传染病的发病趋势,从而对人类健康造成了巨大的威胁。所以加强对气候变化与传染病间关系、预测预报研究,对进一步认识、预防和控制传染病的爆发流行具有重要意义。本文首先阐述了全球气候变化对生物物种的地理分布和人类健康的影响,气候变化改变了生物物种的地理分布范围,增加了某些物种的潜在分布区域,并造成生物物侯期的改变;同时,极端气候事件成为导致种群数量波动的一个重要驱动力。气候变化对人类健康有直接和间接影响,它使得传染病发病率增加、传染病分布范围扩大、人群对疾病易感性增强。文章重点评述了气候变化对疟疾、登革热、霍乱、流行性乙型脑炎、流感、SARS、肠道传染病、鼠疫、血吸虫病等常见传染病流行机制和传播过程的影响研究进展。评述了传染病和气象因子关系分析中常用的定性和定量分析方法,传统的研究多以定性分析为主,方法较单一;目前,利用流行病学资料与同期的气象因子进行单因素相关分析、多元回归分析是常用的研究方法;主成分回归分析、逐步判别分析、灰色关联分析法、RS和GIS等方法近年来逐渐得到应用;数学建模、实验室生物学仿真实验方法是今后需强化的方向。提出了该研究领域国内外研究普遍存在和亟待解决的问题,针对目前的研究现状和存在的问题,提出了未来的研究重点和发展方向。     

Tracking the elusive prion

Prion diseases are infectious neurodegenerative fatal disorders. There are currently no treatments or cures. Considerable evidence suggests that the infectious agent is an abnormally folded protein that promotes or seeds its normal cellular isoform to fold into the infectious form. However, the precise mechanism and factors involved in this conversion remain unknown. A major stumbling block to further investigation has been the inability to seed the formation of new infectious material in vitro. Now, however, infectious material has been generated in a cell-free system. Although this system uses cell lysate rather than pure proteins, it nevertheless opens the door to the elucidation of targets of intervention and the development of useful diagnostic and therapeutic approaches.     

Global mapping of infectious disease

The primary aim of this review was to evaluate the state of knowledge of the geographical distribution of all infectious diseases of clinical significance to humans. A systematic review was conducted to enumerate cartographic progress, with respect to the data available for mapping and the methods currently applied. The results helped define the minimum information requirements for mapping infectious disease occurrence, and a quantitative framework for assessing the mapping opportunities for all infectious diseases. This revealed that of 355 infectious diseases identified, 174 (49%) have a strong rationale for mapping and of these only 7 (4%) had been comprehensively mapped. A variety of ambitions, such as the quantification of the global burden of infectious disease, international biosurveillance, assessing the likelihood of infectious disease outbreaks and exploring the propensity for infectious disease evolution and emergence, are limited by these omissions. An overview of the factors hindering progress in disease cartography is provided. It is argued that rapid improvement in the landscape of infectious diseases mapping can be made by embracing non-conventional data sources, automation of geo-positioning and mapping procedures enabled by machine learning and information technology, respectively, in addition to harnessing labour of the volunteer ‘cognitive surplus’ through crowdsourcing.     

成人急性感染性腹泻治疗新进展

成人急性感染性腹泻与儿童感染性腹泻在发病率、严重程度、预后等方面有所不同,其治疗以补液、止泻为主,必要时使用抗微生物药物。近年来,成人急性感染性腹泻在补液治疗和益生菌、新止泻药物应用等方面更新了一些新的循证医学证据,在进一步确保现有药物安全性的同时促进了腹泻治疗思路与手段的发展。     

实验用生物样品的啮齿类微生物污染的检测管理

实验用生物样品在生物医学研究中有着广泛的应用.生物样品的微生物污染可危及实验动物设施的生物安全以及对动物实验研究造成负面影响.因此在将生物样品接种到啮齿类动物之前,要对其进行检测以确保无啮齿类动物传染性病原体的污染.因为检测技术和经济上的限制和局限性,不可能对所有的啮齿类动物传染性病原都进行检测.本文依据科学文献、笔者的经验以及专家的意见,尝试着去阐述如何建立一个有效可行的生物样品微生物污染检测计划.笔者建议对一些重要的微生物进行检测,并简要综述了选取这些微生物的理由即它们对科研、实验动物生物安全以及职业健康安全的影响.     

Reasons for the increase in emerging and re-emerging viral infectious diseases

In the past two decades, humans have faced many new viral infectious agents in emerging and re-emerging infectious diseases (EIDs). Many factors contribute to the appearance of EIDs. These factors are complex but can be classified into three different categories: virus factors, human factors, and ecological factors. The factors contributing to the cause of such viral infectious diseases will be systematically reviewed in this article.     

Models of epidemics and endemicity in genetically variable host populations

A discrete time genetics model is developed for populations that are undergoing selection due to infectious disease. It is assumed that the generation time of the host and infectious agent are non-synchronous and that only the host population is evolving. Two classes of epidemic processes are considered. The first class is for infectious agents that confer immunity following infection, while the second class is for those that do not confer immunity. The necessary and sufficient conditions are found in order for the disease to persist in a stable polymorphic host population. These conditions are shown to depend on the density of susceptibles, the selection coefficients, and the severity and class of the disease process.     

The COVID-19 epidemic and other notifiable infectious diseases in China

Many infection control measures have been implemented to prevent the spread of SARS-CoV-2 during COVID-19 pandemic. We aimed to investigate the impact of COVID-19 epidemic on the other notifiable infectious diseases in China, including respiratory infectious diseases, diseases transmitted through the digestive tract and animal-borne diseases. Compared with 2019, the overall decline rate of respiratory infectious diseases in 2020 is the highest (60–90%), and the diseases transmitted by the digestive tract and animal-borne diseases are similar at 20–30%. Both hepatitis and sexually transmitted diseases decreased significantly in February, and there were basically no significant changes in other months compared with previous years. The series of measures taken by China government to prevent the spread of SARS-CoV-2 are also very effective in preventing the spread of respiratory infectious diseases. But they also have a certain degree of prevention against notifiable infectious diseases spread by other routes.     

Purification of infectious adenovirus in two hours by ultracentrifugation and tangential flow filtration

Adenoviruses are excellent vectors for gene transfer and are used extensively for high-level expression of the products of transgenes in living cells. The development of simple and rapid methods for the purification of stable infectious recombinant adenoviruses (rAds) remains a challenge. We report here a method for the purification of infectious adenovirus type 5 (Ad5) that involves ultracentrifugation on a cesium chloride gradient at 604,000g for 15 min at 4 degrees C and tangential flow filtration. The entire procedure requires less than two hours and infectious Ad5 can be recovered at levels higher than 64% of the number of plaque-forming units (pfu) in the initial crude preparation of viruses. We have obtained titers of infectious purified Ad5 of 1.35x10(10) pfu/ml and a ratio of particle titer to infectious titer of seven. The method described here allows the rapid purification of rAds for studies of gene function in vivo and in vitro, as well as the rapid purification of Ad5.     

The impact of economic crises on communicable disease transmission and control: a systematic review of the evidence

There is concern among public health professionals that the current economic downturn, initiated by the financial crisis that started in 2007, could precipitate the transmission of infectious diseases while also limiting capacity for control. Although studies have reviewed the potential effects of economic downturns on overall health, to our knowledge such an analysis has yet to be done focusing on infectious diseases. We performed a systematic literature review of studies examining changes in infectious disease burden subsequent to periods of crisis. The review identified 230 studies of which 37 met our inclusion criteria. Of these, 30 found evidence of worse infectious disease outcomes during recession, often resulting from higher rates of infectious contact under poorer living circumstances, worsened access to therapy, or poorer retention in treatment. The remaining studies found either reductions in infectious disease or no significant effect. Using the paradigm of the "SIR" (susceptible-infected-recovered) model of infectious disease transmission, we examined the implications of these findings for infectious disease transmission and control. Key susceptible groups include infants and the elderly. We identified certain high-risk groups, including migrants, homeless persons, and prison populations, as particularly vulnerable conduits of epidemics during situations of economic duress. We also observed that the long-term impacts of crises on infectious disease are not inevitable: considerable evidence suggests that the magnitude of effect depends critically on budgetary responses by governments. Like other emergencies and natural disasters, preparedness for financial crises should include consideration of consequences for communicable disease control.