流行病学课件：第2章 疾病分布

1、1疾病分布Distribution of Disease2疾病的分布是指疾病的人群现象 是描述疾病事件（发病、患病、死亡等） Time （时间） Place （空间） Person（人间） 在流行病学中简称“三间分布”3ExampleYou have been asked to investigate an event in which 2,220 people were exposed and 1,520 of them died. Your role as an epidemiologist is to ask questions about person, place and time.

2、4Contents第一节疾病频率测量指标第二节 疾病流行强度第三节 疾病分布形式Frequency of Disease Measurement Intensity of EpidemicDistributions Pattern of disease5Directions: This chapter describes the basic measures of disease frequency used in epidemiologic research Frequency of Disease Measurement 第一节 疾病频率测量指标6发病频率测量指标患病频率测量指标死亡频率测

3、量指标预期寿命及相关指标Morbidity frequency measuresPrevalence related measuresMortality frequency measuresLife expectancy related measures7一、发病指标发病率（incidence）罹患率（attack rate）续发率（secondary attack rate）8发病率（incidence） 定义 在一定期间内，一定人群中某病新发生的病例出现的频率。 Definition the rate of new cases of a disease in a specified pop

4、ulation over a defined period 发病率= K K=100%,1000/千，或10000/万 一定期间内某人群中某病新病例数同时期暴露人口数 9Incidence rateNumeratorNew (incident) cases appearing during a time period (usually one year)DenominatorAverage population during the time periodMidpoint population estimate Cases per 10X per year Example: 234 per 1

5、00,000 per year12罹患率（attack rate）定义 在某一局限范围，短时间内的发病率。观察时间可以日、周、旬、月为单位。 Definition the proportion of a population affected by the disease during a prescribed, usually short, period of time.13Incidence rate and attack rates An outbreak of hepatitis A in Ajloon from March 1 to march 14 2000 had an atta

6、ck rate of 25 per 1000 The yearly incidence rate of hepatitis A . in Ajloon is 238 per 100,000 per year How do you compare these rates?14Is there an outbreak?Incidence and attack rates compared 1. Adjust population to make rates comparable Divide 238 per 100,000 by 100 2.38 per 1000 per year 2. Adju

7、st time period 2 weeks = 2/52 year 2.38 (2/52) = 0.11 0.11 per 1000 per 2 weeks 南方Schistosomiasis is limited in some provinces in the southHIV infection in Yunnan ProvinceNasopharyngeal carcinoma in GuangdongEsophageal cancer in Henan Jiangsu Qidong Liver CancerHypertension north South 90 Fig18. Chi

8、nas cumulative reported HIV infection distribution by province (1985-2001) 91疾病的城乡分布 The disease city and countryside distribution 城市 City人口多，密度大 Population is many , density is big 交通拥挤，人口流动性大 Traffic congestion, population mobility较少经水传播传染病流行 Less water-borne epidemics 虫媒传染病农村 Insect intermediary

9、infectious disease 城市Insect intermediary infectious disease City某些地方病发病率The incidence of certain endemic diseases呼吸道传染病不易流行Respiratory tract infectious disease not easy popular 疾病的城乡分布 The disease city and countryside distribution 93 疾病的地区聚集性 （endemic clustering） 定义疾病频率高于周围地区的情况 Disease frequency is

10、 higher than the surrounding area 94 地方性疾病（简称地方病） 定义指局限于某些特定地区内相对稳定并经常发生的疾病。在我国地方病指与当地水土因素、生物学因素有密切关系的疾病，其病因存在于发病地区的水、土壤、粮食中 。 Present in a community at all times but in relatively low frequency. Something that is endemic is typically restricted or peculiar to a locality or region. 95判断依据该地区的各类居民、任何

11、民族的发病率均高在其他地区居住的相似的人群中该病的发病频率均低，甚至不发病。incidence of the disease in any ethnic may increase in the residents in the area similar residents lived in other areas have the lower incidence, or even not occur the disease criteria of endemic diseases96criteria of endemic diseaseswho immigrate the area over

12、a period of time, its incidence approaches that in local population; the people emigrate the area, the incidence would reduce, or symptoms alleviate or self-healing.in addition, the local animals are also susceptible to the same disease迁入该地区的人经一段时间后，其发病率和当地居民一致人群迁出该地区后，发病率下降或患病症状减轻或自愈当地的易感动物也可发生同样的疾

13、病判断依据97移民流行病学 （migrant epidemiology） 定义 对移民人群的疾病分布进行研究，以探讨病因。它是通过观察疾病在移民、移民移入国当地居民及原居地人群间的发病率、死亡率的差异，从其差异中探讨病因线索，区分遗传因素或环境因素作用的大小。 98若环境因素是主要因素 移民原居住地人群发病率或死亡率 移民移居地当地居民若遗传因素是主要因素 移民原居住地人群发病率或死亡率 移民移居地当地居民99Local residents in Japan, the United States white and third generation, second-generation Japanese immigrants age specific death rate of gastric cancer Fig19100分析结果注意 移民移居他地的原因及移民本身的人口学特征。 如：年龄、职业、文化水平、社会经济状况、种族和其他人口学因素及其工作条件、生活环境的变化是否和非移民相同。101表6.日本人在美国的日本移民及美国白人一些疾病 的标化死亡率比（1959-1962） 日本移民 疾病 日本人 非美国出生 美国出生 美国白人 食管癌（男） 100 132 51 47 胃癌（女） 100 55 48 18肠癌（男） 100 374 288 489乳腺癌（女） 100