传染病学总论

12传染病学总论IntroductionofLemology浙江大学李兰娟3学习意义及重要性了解传染病的基本理论，基本概念，基本方法掌握传染性疾病发生与发展规律认识突发或新发传染病4概念感染性疾病infectiousdiseases传染病communicablediseases5第一节感染与免疫6一、感染的概念感染：病原体与人体的相互作用感染病：感染后的临床或亚临床表现机会性感染opportunisticinfection条件致病菌conditional(E.coli,Pseudomonas,Fungi)共生状态commensalism7二、感染过程的表现1.清除病原体eliminationofpathogen2.隐性感染covertinfection3.显性感染overtinfection4.病原携带状态carrierstate5.潜伏性感染latentinfection81.清除病原体非特异性防御能力non-specificimmunity特异性免疫功能specificimmunity—主动免疫activeimmunity—被动免疫passiveimmunity92.隐性感染病原体仅诱导机体产生特异性免疫应答，不引起或只引起轻微的组织损伤，在临床上不显出任何症状、体征，甚至生化改变，只能通过免疫学检查才能发现Onlymakethehostproducingspecificimmuneresponse,nothavinghistomorphologicaldamage,nosymptomsandsigns,noanybiochemicalchanges,onlydiscoveredbyimmunologicalexaminations病原体通常被清除，但少数人可转变为病原携带状态Pathogenscanbeeradicatedorcarried103.显性感染病原体侵入人体后，不但诱发免疫应答，而且通过病原体本身或机体的变态反应，导致组织损伤，引起病理改变和临床表现Makethehostproducingspecificimmuneresponse,havingpathologicalchanges显性感染过程结束后，有些传染病可使感染者获得较为稳固的免疫力，另一些传染病免疫力并不牢固Immunitycanbeconsolidatedortemporary114.病原携带状态病原体侵入人体后，人体不出现任何的疾病状态，但能携带并排出病原体，成为传染病流行的传染源Noclinicalmanifestationbutmicroorganismexcreted分类：—按病原体：viruscarrier,bacteriacarrier—按发生和持续时间：convalescent,healthyorincubatorycarrier—按携带病原体的持续时间：acuteorchroniccarrier125.潜伏性感染病原体感染人体后，机体免疫功能足以将病原体局限化但又不足以将病原体清除，病原体长期潜伏起来，待机体免疫功能下降时引起显性感染Locatesthepathogenbutcannotwipesitout,canlatentlyforalongtime,canoccursovertinfection潜伏性感染与病原携带状态的区别？Whatisthedifferentpointbetweenlatentinfectionandcarrierstate?13潜伏感染显性感染病原携带状态隐性感染清除病原体感染谱频度14三、感染过程中病原体的作用侵袭力invasiveness毒力virulence数量quantityofpathogens变异性variability151.侵袭力直接侵入人体invadedirectlyLeptospira,filariformlarvaofAncylostoma先黏附于肠或支气管黏膜表面，再侵入组织细胞，如志贺菌、结核分枝杆菌。致泻性大肠埃希菌能表达受体（定植因子）和小肠细胞结合adhere,colonizeandproduceenterotoxin:Vibriocholera通过细菌表面成分（如伤寒沙门菌Vi抗原）抑制吞噬而促进病原体扩散promotespread：ViantigenofSalmonellatyphi162.毒力毒素toxins—外毒素exotoxin(Vibriocholera,Clostridiumtetani,Corynebacteriumdiphtheriae)—内毒素endotoxin(S.typhi,Sh.dysentery)其他毒力因子—穿透能力filariformlarvaofAncylostoma—侵袭能力Sh.dysenteriae—溶组织能力Entamoebahistolytica173.数量同一种传染病，入侵病原体的数量与致病能力成正比Thenumberofinvadingpathogenispositiverelationwiththepathogenicityinthesameinfectiousdisease不同的传染病，能引起疾病的最低病原体数量可有较大差异Theleastnumberofthepathogentoinducediseasediffergreatlyindifferentdiseases.Forexample,S.typhiis10000andSh.dysenteriaeisonly10184.变异性变异因素variationfactors—环境environmental、药物drug、遗传hereditary变异类型variousforms—致病力变异pathogenicityvariation—抗原性变异antigenicvariation—耐药性变异drug-resistantvariation19四、感染过程中的免疫应答保护性免疫应答：有利于机体抵抗病原体非特异性免疫—天然屏障naturalbarriers—吞噬作用phagocytosis—体液因子humoralfactors特异性免疫—细胞免疫cell-mediatedimmunity—体液免疫humoralimmunity变态反应：促进病理改变—特异性20第二节传染病的发病机制21一、传染病的发生与发展入侵部位positionofinvasion机体内定位locationinthebody排出途径routeofexclusion22二、组织损伤的发生机制直接损伤directdamage毒素作用actionofthetoxin免疫机制immunitymechanism23三、重要的病理生理变化发热pyrexia急性期改变—蛋白代谢—糖代谢—水电解质代谢—内分泌改变24第三节传染病的流行过程25一、流行过程的基本条件传染源sourceofinfection—患者measles—隐性感染者poliomyelitis—病原携带者typhoidfever,bacillarydysentery—受感染的动物rabies,plague,leptospirosis,typhus26一、流行过程的基本条件传播途径routeoftransmission—呼吸道传播—消化道传播—接触传播contagioustransmission—虫媒传播arthropod-bonetransmission(blood-suckingarthropods:mosquito,lice,flea,sandfly,mite,tick)—血液、体液传播blood,bloodproductsandbodyfluid—其他：mothertoinfant(verticaltransmission)27一、流行过程的基本条件人群易感性susceptibilityofthecrowd—易感者Theratioofsusceptiblepersonsdecidethecrowdsusceptibility—流行的周期性Thecrowdsusceptibilityisrelationtoperiodicityofanepidemic—人工免疫影响流行的周期性Theperiodicityofanepidemicmaybepreventedbyartificialactiveimmunization28二、影响流行过程的因素自然因素naturalfactors—geography,climate,ecology—疫源地focusofinfection—自然疫源性传染病/人兽共患病zoonosis(plague,leptospirosis,humanavianinfluenza)社会因素socialfactors—socialbackground,economicalcondition,culturallevel,anti-epidemicmeasures29第四节传染病的特征30一、四大基本特征病原体pathogens传染性infectivity流行病学特征epidemiologicfeature感染后免疫postinfectionimmunity311.病原体有特异性specific应用新技术可发现更多病原体Befoundwithnaturalscienceadvancements322.传染性是传染病与其他感染性疾病的主要区别Infectivityisthemaindistinctionbetweentheinfectiousdiseasesandotherinfection可依据传染期隔离患者“Infectiveperiod”canbeusedasaruletoisolatethepatient333.流行病学特征流行性endemic(sporadic,epidemic,pandemic&epidemicoutbreak)季节性seasonaldistributionintime地方性regionaldistributioninspace外来性exotic(e.g.choleraandyellowfever)344.感染后免疫属特异性、主动、保护性免疫specific,active,protective,cantransfertonewbornsthroughplacenta持续时间在不同传染病中有很大差异lastingtimevarieswiththediseases持续时间短可出现再感染、重复感染“concomitantimmunity”(helminthiasis)35二、急性传染病的四期经过潜伏期incubationperiod前驱期prodromalperiod症状明显期periodofapparentmanifestation恢复期convalescentperiod361.潜伏期常态分布normaldistribution,asimportantevidenceofobserving,detectingthecontactinquarantinework随病原体的种类、数量、毒力与人体免疫力的强弱而定relatedwithinvadingquantityofpathogens,timeofthetoxin(bacterialfoodpoisoning),woundlocation(rabies)潜伏期短的传染病，流行时往往呈暴发372.前驱期非特异性nonspecific为许多传染病所共有coexistinmanyinfectiousdiseases一般持续1～3天usuallypersistonetothreedays,evenmiss(suddenonset)383.症状明显期充分表现特有症状和体征Specialsymptomsandsignspresentedenough,suchasrashes,jaundice,heptomegaly,splenomegaly,meningealirritationsigns为许多急性传染病所共有especiallyinsomeacutediseases—me