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Epidemiology and Its Applications
The word epidemiology comes from the Greek words epi, meaning on or upon, demos. meaning people . and logos . meaning the study of . in other words , the word epidemiology has its roots in the study of what befalls a
population. Epidemiology is a scientific discipline with sound methods of scientific inquiry at its foundation. It is data-driven and relies on a systematic and unbiased approach to the collection.analysis. and
interpretation of data. Basic epidemiologic methods tend to rely on careful observation and use of valid comparison groups to assess whether what was observed. such as the number of cases of disease in a particular area during a particular time period or the frequency of an exposure among persons with disease.
differs from what might be expected. 流行病学epidemiology一词来源于希腊词，epi-，意为“在……之上”，demos意为“人群”，logos意为“关于……的研究”。换言之，epidemiology植根于某个人群有关的疾病研究。流行病学从根本上是一门有着严密科学方法的学科。它是数据驱动，用系统、客观的方法收集、分析和解释数据。基本的流行病学研究方法依靠仔细的观察，运用有效的对照组来衡量观察对象，比如在一个特定时间段，一个特定的区域疾病的发病数量或是和一种疾病发病人群的接触频率，和你预测的有何不同。
Epidemiologists assume that illness does not occur randomly in a
population, but happens only when the right accumulation of risk factors or determinants exists in an individual. To search for these determinants, epidemiologists use analytic epidemiology or epidemiologic studies to provide the .'Why\
with different rates of disease differ in their demographic characteristics. genetic or immunologic make-up. behaviors, environmental exposures. or other so-called potential risk factors. ideally. the findings provide
sufficient evidence to direct prompt and effective public health control and prevention measures.
Epidemiology and the information generated by epidemiologic methods have been used in many ways. Some common uses are described below, been used in many ways. Some common uses are described below.
流行病学家认为疾病不会随意地在某个人群中发生，但存在与个体中的风险因子或决定因素累积到一定程度才可能发生。为了查明这些影响因素，流行病学家运用分析流行病学或流行病学研究方法来解释流行病的形成原因和传播原因。他们评估有不同发病率的人群是否在诸如人口学特征、基因及免疫构成、行为特点、环境接触或是其他所谓的潜在风险因素等方面有所不同。理想的话，这些发现将会提供充足的证据来指导直接、迅速、有效地公共卫生控制及防御措施。 流行病学及其研究方法所带来的信息已经被广泛运用。常见的用途有
Assessing the community's health评估人群的健康
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Public health officials responsible for policy development.
Implementation, and evaluation use epidemiologic information as a factual framework for decision making. To assess the health of a population or community. relevant sources of data must be identified and analyzed by person. place, and time. Sometimes, more detailed date may need to be
collected and analyzed to determine whether health services are available. accessible. effective, and efficient.
负责政策制定、实施和评价的公共卫生官员将流行病学信息作为决策的事实框架。为了评估某个人群或社区的健康状况，相关的数据来源必须经过人口、地点和时间的认定和分析。有时，为了确保医疗服务适当、充足、有效和高效，需要收集和分析更多的详细数据。
Making individual decisions影响个人的选择
Many individuals may not realize that they use epidemiologic
information to make daily decisions affecting their health. When persons decide to quit smoking. climb the stairs rather than wait for an elevator, eat a salad rather than a cheeseburger with fries for lunch, or use a condom. they may be influenced consciously or unconsciously, by
epidemiologists' assessment of risk. Many epidemiologic findings are
directly relevant to the choices people make every day. choices that affect their health over a lifetime. 许多人没有到他们利用率流行病学的信息来做出影响自身健康的日常决策。当人们决定戒烟、选择爬楼梯而不是等电梯、中餐吃沙拉而不是薯条加面包或使用避孕套的时候，他们有意或无意地受到了流行病学家对风险评估的影响。许多流行病学上的发现和人们每天做出的选择或影响他们一生健康的选择直接相关。
Completing the clinical picture填补临床拼图
When investigating a disease outbreak. epidemiologists rely on health-care providers and laboratorians to establish the proper diagnosis of individual patients, But epidemiologists also contribute to physicians' understanding of the clinical picture and natural history of disease. For example, in late 1989, a physician saw three patients with unexplained eosinophilia ( an increase in the number of a specific type of white blood cell called an eosinophilia) and myalgia (severe muscle pains. Although the physician could not make a definitive diagnosis. he notified Public health
authorities. Within weeks, epidemiologists had identified enough other cases to characterize the spectrum and course of the illness that came to be known as eoslnophilia-myalgia syndrome. 研究疾病的爆发时，流行病学家以来医护人员和实验室工作人员来确立对病人的正确诊断。但流行病学家也会帮助内科医生了解疾病的临床表现和历程。例如在1998年后期，一位医生接触到三个有着不明原因的嗜酸性粒细胞过多（被称为特定的一种嗜曙红血球数量的增加）和肌痛的病例。尽管医生不能确诊，但他知会了公共卫生机构的权威。几周内，流行病学家已经找到了足够的其他病例来明确后来被称为嗜酸性粒细胞过多肌痛综合症的范围和历程。
Searching for causes寻求病因
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Much epidemiologic research is devoted to searching for causal factors that influence one's risk of disease. leally. the goal is to identify a cause so that appropriate public health action might be taken. One can argue that epidemiology can never prove a causal relationship between an exposure and a disease, since much of. epidemiology is based on ecologic reasoning. Nevertheless, epidemiology often
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provides enough Information to support effective action. Examples date from the removal of the handle from the Broad St. pump following John Snow's investigation of cholera in the Golden Square area of London In 1854 , to the withdrawal of a vaccine against rotavirus in 1999 after epidemiologists found that it increased the risk of intussusception. a potentially life-threatening condition. Just as often, epidemiology and laboratory science converge to provide the evidence needed to establish causation. 大量的流行病学的研究致力于寻找影响个人患病率的病因，目标是能确定病因，从而可能采取适当的公共卫生措施。有人认为因为许多流行病学是建立在生态推理的基础上，因此无法证明某种疾病的因果关系。然而，流行病学经常能提供足够的信息去支持有效的措施。此类例子可以追溯到1854年，约翰·斯诺对伦敦黄金广场的霍乱研究促成政府拆除了宽街的饮水泵把手：还有1999年轮状病毒疫苗的召回正是因为流行病学专家发现该疫苗有可能增加患肠套叠(一种潜在的威胁生命的情形)的风险。流行病学与检验学共同提供证据帮助确定病因。
【第二篇】Hepatitis B Virus Intrauterine Transmission
Hepatitis B (HB) is still a major epidemic worldwide and threatens
people's life and health tremendously. China is a prevalent area of HBV The positive rate of NBsAg in normal population is up to 10 percent and over 120 million people are the carrier of HBV in China. Most of them have been caused by mother to infant transmission. It was presumed that HBV could be transmitted from pregnant woman to her retus through the placenta. when HBV was first discovery However. presence of HBV intrauterine( 子宫内的) infection was not confirmed t川mid-80s. when HBV DNA and HBSAG were
detected in liver cells of aborted fetus from HBV positive pregnant women. by using immunopathologic and molecular biologic technology. 乙肝是在世界最流行的病，严重的威胁着人类的健康和生命，中国是HBV病毒的广泛的发病区，在中国，正常人群中HBsAg的阳性率达到10%，超过1亿两千万是HBV病毒的携带者，他们中，大部分是通过母婴传播造成的，在HBV病毒首次发现时，人们认为HBV病毒可能是从孕妇通过胎盘传播给胎儿的，然而，直到80年代中期，通过免疫病理学和分子生物学技术在HBV阳性孕妇流产的胎儿的肝细胞中检测到HBV的DNA和HBsAg时，HBV宫内感染才被确认。
Intrauterine transmission refers to the transmission mode that HBV
infects fetus through placenta. This infection is defined as intrauterine infection. HBV intrauterine transmission was not completely cut off by hepatitis B vaccine and hepatitis B immunoglobulin So the neonates suffering HBV infection by Intrauterine transmission could become the
chronic virus carriers throughout their life . and 25 to 50 percent of them would develop into fiver cirrhosis or liver cancer. if female is infected, she could. transmit HBV to her children by the same ways. In this cycle. intrauterine transmission will cause severe consequence There are about 100 to 200 thousand, The neonates who develop into HBV carrier status by intrauterine infection every year in China .World Health Organization ( WHO ) has proclaimed to \2010\transmission is one of the key requirements to control the epidemic of hepatitis B.
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宫内感染指HBV通过胎盘传播的方式感染胎儿，这种感染被称为宫内感染，HBV宫内感染不能被乙肝疫苗和免疫球蛋白完全阻断，因此，受到通过宫内传播感染HBV的新生儿将成为终生的病毒携带者，并且他们中有25%—50%可能会发展为肝硬化或肝癌。如果女性被感染，她可以以相同的方式将HBV传给她的孩子，在这种循环下，宫内感染将会导致严重的后果。在中国，每年约有10万到20万由宫内感染而成为HBV携带者的新生儿。世界卫生组织已经宣告“到2010年要控制乙肝的全球流行”，因此，了解潜在的HBV宫内感染的机制是控制乙肝流行的主要要求之一。
However. until the beginning of 1990 's. the reports on the mechanism of HBV intrauterine transmission were still limited in the world. although there were many studies about the incidence rate of HBV Intrauterine transmission. Including more than 20 reports en China. There were some reasons for that. First. it was still short history since population received regular inoculation of hepatitis B vaccine. and perinatal stage transmission and horizontal transmission were more predominant than
intrauterine transmission with little attention to the prevention against intrauterine transmission. Secondly. it was difficult to facilitate
researches about mechanism of HBV intrauterine transmission because of the involvement of fetus. neonates and placenta.
然而，直到1990年代初，虽然有很多关于HBV宫内感染发生率的研究，包括中国超过20篇的报告。世界上关于HBV宫内感染机制的报告仍然很局限，这是由多种原因造成的，首先，从人类接受正规的乙肝疫苗的预防接种仍然是很短的一段历史，并且围产期感染和水平的感染比宫内感染更主要，人们没有关注预防宫内感染，其次，由于胎儿、新生儿和胎盘的涉及，很难帮助研究者关于HBV宫内感染的机制。
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医学英语教程综合教程第六单元
