《食物中毒及其预防》PPT课件.ppt

8/3/2023,Food poisioning,1,Food poisoning and Prevention,食物中毒及其预防,8/3/2023,Food poisioning,2,食物中毒的概述我国食品安全现状食源性疾病食物中毒的概念发生原因流行病学特点分类发病机理调查与处理,教学安排主要内容,细菌性食物中毒沙门菌副溶血弧菌葡萄球菌肉毒梭菌,病原发生原因流行病学特点发病机制临床表现诊断与预防,化学性食物中毒亚硝酸盐、农药有毒动植物食物中毒鱼类、贝类、毒蕈真菌及其毒素食物中毒镰刀菌、节菱孢霉,8/3/2023,Food poisioning,3,Food-borne illness：,disease acquired from eating or drinking contaminated food or water.This term can include any type of illness that you can get from eating food that is contaminated.It can include illness from bacteria,viruses,parasites,chemicals,allergies or naturally occurring poisons such as some mushrooms.,Two major categories:INTOXICATIONS and INFECTIONS.The former is the result of ingesting toxins produced by microbes that have grown on the food prior to it being eaten.The latter is the result of the food serving as a fomite that carries an infectious pathogen deep into the juicy recesses of a body where it is able to gain a foothold.,食源性疾病通过摄食进入人体内的各种致病因子引起的、通常具有感染性质或中毒性质的一类疾病。,8/3/2023,Food poisioning,4,8/3/2023,Food poisioning,5,Contents,源于传统的食物中毒，经食物而感染的肠道传染病、食源性寄生虫病，由食物中有毒、有害污染物所引起的中毒性疾病；慢性退行性疾病(心脑血管疾病、肿瘤、糖尿病等)，食源性变态反应性疾病，食物中某些污染物所致的慢性中毒性疾病等,8/3/2023,Food poisioning,6,Food Safety食品安全,水食品合格率 面粉，大米蔬菜、水果鸡，猪肉酸奶,我国每年食物中毒人数：2040万,Data FromUSA/CDC,8/3/2023,Food poisioning,7,acidophilus milk-酸奶,北京抽查酸奶合格率为55.2%1.产品微生物超标2.防腐剂超标3.亚硝酸盐、硝酸盐超标4.乱用商标，误导消费者5.蛋白质、脂肪含量参差不齐,8/3/2023,Food poisioning,8,国内外食品安全事件,1.1987年12月至1988年月上海甲型肝炎暴发性流行事件30万市民染上肝炎2.1996年6月27日至7月21日，云南曲靖地区会泽县发生食用散装白酒甲醇严重超标的特大食物中毒事件,192人中毒，35人死亡，6人致残。3.1997年6月底至7月上旬，云南思茅地区发生群众自行采食蘑菇 中毒事件，共有255人中毒，死亡73人。4.1996年5月下旬，日本几十所中学和幼儿院相继发生6起集体大 肠杆菌O157中毒事件，中毒超过万人，死亡11人，波及44个府县.5.1998年2月，山西省朔州、忻州、大同等地区连续发生的多起重大的假酒中毒事件，有200多人中毒，夺去了27人生命.6.1999年1月，广东省46名学生的食物中毒；同年6月，某省一医院接受了34人中毒事件，中毒原因都是食用带有甲胺磷农药残留的“蔬菜”.,8/3/2023,Food poisioning,9,7.最早发生并流行于英国的牛海绵状脑病（疯牛病），自1987年至1999年期间证实的病牛就达17余万头，英国为此损失300亿美元。8.1999年5月在比利时“二恶英污染食品”事件，造成的直接损失 达3.55亿欧元，如果加上与此关联的食品工业，损失已超过上 百亿欧元。9.1999年年底，美国李斯特菌食物中毒事件。美国密歇根州14人 死亡，在另外22个州也有97人因此患病，6名妇女流产。10.2000年底至2001年初，法国发生李斯特氏菌污染食品事件，有6人死亡。11.2000年6月，日本雪印牌牛奶14 500多人患有腹泻、呕吐疾病，180人住院治疗，使占牛奶市场总量14的雪印牌牛奶进行产品回收，全国21家分厂停业整顿。12.2001年1月，浙江省杭州市60多人到医院就诊，症状为心慌、心跳加快、手颤、头晕、头痛等，原因是食用了含有“瘦肉 精”(即盐酸克伦特罗)的猪肉。,8/3/2023,Food poisioning,10,8/3/2023,Food poisioning,11,食品卫生大案（4 7 月）,浙江省白砂糖中添加“吊白块”中毒重庆市“毛发水”酱油广东劣质大米中毒江西市场河豚鱼中毒内蒙古死因不明原因羊 肉中毒,天津输液瓶灌装酱油江西病死肉加工食品四川非法食品非法宣传重庆市非法加工伪劣食品广西“吊白块”粉丝重大食物 中毒,2001卫生部公布,8/3/2023,Food poisioning,12,Food Poisoning,食物中毒是指摄入含有生物性、化学性有毒有害物质的食物或把有毒有害当作食物食物摄入后出现的急性或亚急性疾病。,Food poisoning refers to an acute illness caused by ingestion of food contaminated by bacteria,bacterial toxins,viruses,natural poisons,or harmful chemical substances.It is characterized by a short incubation period(1 wk or less).The symptoms,varying in degree and combination,include abdominal pain,vomiting,diarrhea,headache,and prostration;more serious cases can result in life-threatening neurologic,hepatic,and renal syndromes leading to permanent disability or death.,1994年卫生部：食物中毒诊断标准及技术处理总则(B14938-94),8/3/2023,Food poisioning,13,Kernel in the definition,Normal amount 正常数量The status can be eaten 可食状态Toxic food 有毒食品Acute poisoning 急性中毒No-infection 非传染性,8/3/2023,Food poisioning,14,The source of the toxic food,1.The contamination of bacteria and toxin食品受到某些细菌和毒素的污染2.Mixture of poisoning chemical substance有毒化学物的混入3.Toxic itself in nature食品本身有毒4.Inappropriate storage储存方式不当5.Misuse.误食,8/3/2023,Food poisioning,15,Distinguished Diagnosis,1.Engorgement 暴饮暴食2.Hyper metamorphosis 变态反应3.Infectious disease,verminosis 人蓄共患 传染病，寄生虫病4.Diarrhea,enteritis 痢疾、伤寒、肠炎5.Placing toxin 人为投毒,8/3/2023,Food poisioning,16,Characteristic of Food Poisoning,1.暴发性2.症状基本相似3.集体发病，人与人之间不传染4.与食物有关5.采取措施后控制快，无流行病余波,8/3/2023,Food poisioning,17,Classification of food poisoning,1.细菌性食物中毒2.有毒动植物食物中毒3.有毒化学物质食物中毒4.真菌毒素和霉变食品中毒,8/3/2023,Food poisioning,18,Epidemic Characteristic,食物中毒发病的原因分布特点：微生物、化学性食物中毒食物中毒的食品种类分布特点动物性、植物性食物中毒发病的季节性、地区性分布特点,8/3/2023,Food poisioning,19,8/3/2023,Food poisioning,20,8/3/2023,Food poisioning,21,19982000年北京市食物中毒致病原因分类,8/3/2023,Food poisioning,22,化学性食物中毒有增加的趋势,据卫生部全国重大食物中毒情况通报：1999年化学性食物中毒的人数占中毒总人数的29%，2000年化学性食物中毒的人数上升到占中毒总人数的35%；2001年第二季度化学性食物中毒发生的起数和中毒人数居首位。造成中毒的有毒物质主要是农药（包括灭鼠药）、亚硝酸盐、违法掺入食品中的非食品原料等。,8/3/2023,Food poisioning,23,近几年以散发为主未报告的因食用猪肝所致兽药盐酸克伦特罗（瘦肉精）食物中毒累计已有10起以上；此类因在畜禽养殖过程中滥用各种兽药和饲料添加剂，造成畜禽产品中残留高浓度的兽药导致人的急性中毒是近年来化学性食物中毒的新特点。随着种植业和养殖业的发展，越来越多的化学物质可能被应用到传统的种植业和养殖业中，成为化学性食物中毒的新隐患。,8/3/2023,Food poisioning,24,有毒动植物食物中毒,90%以上是集体供餐单位发生的扁豆中毒，而扁豆中毒完全可以在烹调过程中通过延长加热时间破坏扁豆中的毒素来避免中毒的发生,8/3/2023,Food poisioning,25,造成食物中毒的责任单位,以饮食服务单位和集体食堂为主，但由送餐企业导致的以中小学生为主的食物中毒近年来有增加的趋势。,Food poisoning tends to occur at picnics,school cafeterias,and large social functions.These are situations where food may be left unrefrigerated too long or food preparation techniques are not clean.Food poisoning often occurs from undercooked meats or dairy products(like mayonnaise mixed in cole slaw or potato salad)that have sat out too long.,8/3/2023,Food poisioning,26,食物中毒漏报问题,据WHO有关专家估计，发展中国家报告的食物中毒仅占实际发生的食物中毒的5%或更低。,8/3/2023,Food poisioning,27,Epidemiological Characteristic,Bacterial food poisoning细菌性食物中毒,发病季节性明显有些还具有一定地区性中毒食品主要为动物性食品发病率高，病死率因病原而异,8/3/2023,Food poisioning,28,3 Pathogen-发生原因：,牲畜屠宰 销售受致病菌污染 食物贮藏不当 致病菌繁殖，产生毒素 食物灭菌不彻底、生熟交叉污染或 从业人员带菌污染,8/3/2023,Food poisioning,29,Mechanism of poisoning,致病菌 肠道继续繁殖并侵袭肠粘膜及粘膜下层 吞噬细胞吞噬或杀灭肠粘膜炎性反应病原菌解体内毒素体温调节中枢体温升高,-organisms multiply within and invade the gut;incubation period of several days；E.coli,Salmonellosis,Campylobacter（弧菌）,Shigella（志贺氏菌）,Yersinia rarities（耶尔森氏菌）,Infectious type（感染型）,8/3/2023,Food poisioning,30,-release pre-formed toxin causing rapid onset of symptoms;usually short duration,afebrile:Staphylococcus aureus,Bacillus cereus.,toxin type（毒素型）,致病菌污染食物并大量繁殖产生肠毒素 吸收入血 呕吐中枢 呕吐 腺/鸟苷酸环化酶ATP，GTP cAMP，cGMP Cl 分 泌 亢 进 细胞分泌功能改变 腹泻 Na+、H2O吸收抑制,8/3/2023,Food poisioning,31,intermediate-type（混合型）,-pre-formed toxin released once organism has multiplied within the gut;12 hour incubation period:V.parahemolyticus,（副溶血弧菌）等,侵袭肠粘膜致病菌急性胃肠道症状产生肠毒素,8/3/2023,Food poisioning,32,Salmonella沙门菌食物中毒,G-杆菌，周生鞭毛，O抗原：67种（A、B、C1、C2、C3、D、E1、E4、F 9类）2300个以上的血清型,我国超过161种鼠伤寒，猪霍乱，肠炎沙门菌菌毛引起侵入性腹泻,1病原菌（pathogeny）,8/3/2023,Food poisioning,33,8/3/2023,Food poisioning,34,8/3/2023,Food poisioning,35,2流行病特点,1)引起中毒的食物：畜禽肉、蛋类、奶及其制品2)食物中沙门菌的来源：畜禽肉类、蛋类及其制品，奶 类及其制品，熟制品 原发性感染 肉 生前感染 全身感染 类 继发性感染 宰后污染：局部感染3)发病季节分布4)发病率：活菌量、菌型、个体易感性,8/3/2023,Food poisioning,36,mechanism of poisoninginfection:main toxin:minor,肠粘膜炎性反应：充血、WBC浸润、水肿、渗出等Sal.侵袭肠及粘膜粘膜下层 淋巴细胞吞噬 吞噬细胞激 暂时性菌血病 Sal.在吞噬细 活杀死Sal.和全身性感染 胞中继续繁殖病原菌解 激活WBC趋化因子 肠粘膜局部炎症体，释放内 毒 素 致热源 体温调节中枢 体温升高,abbreviation,8/3/2023,Food poisioning,37,8/3/2023,Food poisioning,38,以急性胃肠炎型为主，并伴发烧:潜伏期短,，数小时，长23天，一般1224小时主要症状:1.前驱症状：头晕，头痛，恶心，食欲不振2.先呕吐，后腹痛3.大便颜色：黄色，或绿色，水样便，并带脓血黏液4.发烧：38400C 5.病程：35天6.重症病人：死亡率1%,类霍乱型类伤寒型类感冒型,急性胃肠炎型,4.Clinical manifestation,8/3/2023,Food poisioning,39,5.Diagnosis,Clinic Diagnosis临床表现，流行病学特点发病季节膳食内容集体发病临床症状Pathogenic Diagnosis,8/3/2023,Food poisioning,40,Pathogenic Diagnosis,1.细菌学检查-分离培养病原菌2.血清学检查-分型鉴定 血清凝集试验:1:2040 正常1:100 可疑1:200 阳性715天 两次,8/3/2023,Food poisioning,41,8/3/2023,Food poisioning,42,8/3/2023,Food poisioning,43,8/3/2023,Food poisioning,44,8/3/2023,Food poisioning,45,6.Preventive measurement,Prevent ContaminationControl Growth and ReproduceKilling Pathogen Completely,8/3/2023,Food poisioning,46,Prevent Contamination,加强动物的饲养管理动物检疫宰杀-销售整个过程防交叉感染,8/3/2023,Food poisioning,47,Control Growth and Reproduce,Be careful for your foodStorage temperatureStorage time,Killing Pathogen,Center temperature 中心温度 80 12 min:for Sal.,？,8/3/2023,Food poisioning,48,WHO Golden Rules for Safe Food Preparation,Choose foods processed for safetyCook food thoroughlyEat cooked foods immediatelyStored cooked foods thoroughlyReheat cooked foods,WHO,8/3/2023,Food poisioning,49,V.Parahaemolyticus副溶血性弧菌,8/3/2023,Food poisioning,50,Pathogen,1.嗜盐菌:halophilic,or salt-requiring organism 2.最适温度：3037，繁殖快，一世代时间：10分钟3.对酸敏感的：sensitive to acid4.神奈川现象：Kanagawa hemolysin Research has found that some strains of V.Parahaemolyticus associated with gastroenteritis produce a b-hemolysis of human erythrocytes,a reaction known as the Kanagawa phenomenon.5.血清型：与致病性无关，流行病调查有意义菌体抗原：O抗原夹膜抗原：K抗原鞭毛抗原：H抗原,8/3/2023,Food poisioning,51,Creating leaks in a cells membrane is another way of killing cells.Bacteria use hemolysin to put holes in our membranes.,8/3/2023,Food poisioning,52,Epidemiological Characteristic,1.Distribution：a worldwide distribution in estuarine and coastal environments 近海海湾，近海淡水，富含有机物（中国、日本多见）2.Season：warmer months（79月）Incidences correlate with water temperature.It attaches to plankton,which is eaten by the fish,later eaten by people.3.Susceptibility:4.Poisoning food：marine product including many species of fish,shellfish,and crustaceans（crabs,shrimp,and lobsters）.（检出率与季节有关）墨鱼：93%，蟹：79.8%，带鱼：41.2%，大黄鱼：27.3%,8/3/2023,Food poisioning,53,V.parahaemolyticus has been implicated in numerous outbreaks of seafood-borne gastroenteritis in the United States.Crab,oyster,shrimp,and lobster were implicated in 14 outbreaks,which may have resulted from the consumption of raw or insufficiently heated seafood or properly cooked seafood contaminated after cooking.,8/3/2023,Food poisioning,54,Mechanism-发病机理,感染型中毒：活菌侵袭肠粘膜肠道毒素型中毒：耐热性溶血毒素中毒症状,混合型,8/3/2023,Food poisioning,55,Clinical Manifestation,1.潜伏期短Usually these symptoms occur within 24 hours of ingestion.Illness is usually self-limited and lasts 3 days.Severe disease is rare and occurs more commonly in persons with weakened immune systems.2.腹痛（阵发性）、腹泻、呕吐Intense abdominal pain,vomiting,and diarrhea.In most cases,the stool was watery,but there were some cases of bloody stool.Coldness of extremities,increased pulse,and constriction of blood vessels were also reported.Less commonly,this organism can cause an infection in the skin when an open wound is exposed to warm seawater.3.预后,8/3/2023,Food poisioning,56,Background,1998年8月1日，我市某酒店职工加餐，800左右从某熟食店购得17只盐水鸭，其中3只由冷盘间厨师领去制作冷盘供应顾客；其余14只存放于厨房生配案板上作职工加餐用。约900开始由一帮厨切好装盘，仍放置在厨房内，从10301130职工分别食用。自8月2日凌晨100上午900陆续有50名职工发病住院治疗，主要症状为腹痛、腹泻、呕吐，3日大多痊愈出院。采集1日午餐职工用餐所使用的刀板刮取物，帮厨所用抹布及2例病人大便，均检出副溶血性弧菌；采集冷盘间冰箱剩余盐水鸭，未检出副溶血性弧菌。当日食用冷盘间制作的盐水鸭的顾客未发现异常。,details of a case on V.Parahemolyticus,8/3/2023,Food poisioning,57,Analysis,加工场所条件及人员经调查得知，该帮厨平时负责宰杀海鲜，当日所用刀、板、抹布均为日常宰杀海鲜用，未作消毒。时值盛夏，气温在30以上，厨房无降温设施，温度更高，适宜细菌生长繁殖，食用间隔期(盐水鸭自购回到食用)在2h以上，存放容器均为切配生菜所用容器；而供应顾客的冷盘在一专室制作，有降温及冷藏设施，工具容器均专用，并由专人操作。,8/3/2023,Food poisioning,58,Causation,从调查结果可以看出，这是一起典型的由于生熟不分，导致副溶血性弧菌污染其它食物而引起的食物中毒。这与酒店内部管理不善，操作者卫生知识缺乏有直接关系；而所有的环境条件又正好适宜于副溶血性弧菌的生长繁殖，最终导致了这次中毒的发生。,8/3/2023,Food poisioning,59,Reflection,1.副溶血性弧菌广泛分布在夏季的沿岸海水中，鱼贝类海鲜受污染的可能性很高，配制时应特别注意通过烹调用具和手等污染其它食品的可能。,根据本菌在10以下不发育，而在25以上增殖速度为金黄色葡萄球菌和沙门氏菌等的2倍的特点，烹调后的食品应尽快吃完，减少污染繁殖的机会。,8/3/2023,Food poisioning,60,2.加强对酒店管理人员及厨师的卫生知识培训，提高他们的卫生意识，特别要强化厨师生熟分开的意识，对直接入口熟卤菜的加工制作真正做到“五专”。3.在细菌性食物中毒高发的夏秋季，卫生监督部门要加大监督力度，提高监督水平，将食品加工过程中存在的卫生问题作为监督的重点。并广泛做好宣传，提高群众自我保护意识，防止细菌性食物中毒的发生。,The symptoms common to all patients were most people become infected by eating raw or undercooked shellfish,particularly oysters.,8/3/2023,Food poisioning,61,Staphylococcus aureus葡萄球菌肠毒素食物中毒,8/3/2023,Food poisioning,62,8/3/2023,Food poisioning,63,1Pathogeny,种属：微球菌科（Micrococcaceae）、G+球菌分类：A、B、C1、C2、C3、D、E、F（8 serum type）.Type A:most common,and poison.凝固酶 致病力习性：适温37，较耐热，兼性厌氧，耐盐，对营养条件要求不高，最常见的化脓性球菌之一，自然界分存广泛.肠毒素（enterotoxin）结构：蛋白质类毒素，分子量2600030000毒性：1g/kg.bw即可引起食物中毒耐热：100下可耐受30min，破坏食物中的肠毒素100,2小时.抗酶解：人体蛋白酶不能消化分解,8/3/2023,Food poisioning,64,2Epidemiological Characteristic,1）发病季节:2）引起中毒的食品：奶及奶制品最为常见（营养 丰富，水分充足）3）食物中葡萄球菌的来源：葡萄球菌广葡萄球菌存在于空气、土壤、水中患化脓性皮肤病，急性上呼吸道炎症和口腔疾患的病人，鼻腔带菌率为83.3%,健康人为2030%人类带菌是污染食品的 主要原因,8/3/2023,Food poisioning,65,S.Aureus in human,S.aureus is one of the major causes of hospital-acquired infection.One study ranked it fourth in a listing of the“Pathogens Most Frequently Isolated From Hospitalized Patients When All Anatomic Sites Are Considered”.Approximately 40%of the general population and 50 90%of health care practitioners harbor an S.aureus colony in their anterior nasal passage.Infection becomes a problem when bacteria migrate from their normal habitat,especially in individuals already suffering from a compromised immunologic response.,8/3/2023,Food poisioning,66,4）葡萄球菌的产毒条件,食物的成分和性质（含淀粉和水丰富的食品）污染程度（106 109/g）适宜的温度（2530，510h）足够的潜伏期,8/3/2023,Food poisioning,67,切粉的生产工艺（不含现做现卖的切粉）大米水冼3次，浸泡23小时磨浆蒸煮风冷刷食用油切条装筐榨粉的生产工艺（不含现榨现卖的生榨粉）大米水冼、浸泡磨浆蒸煮成块状压榨成圆条状煮熟水漂（冷）装箱,米粉也是常见的中毒食品,8/3/2023,Food poisioning,68,3.Poisoning Mechanism,The toxins most relevant to disease causing symptoms in humans are the superantigens and-toxins.The-toxins oligomerize to form pores in the host cellular membrane,allowing cellular contents to leak into the extracellular matrix.The superantigens,consisting of enterotoxins and the toxic shock syndrome toxin,are responsible for S.aureus-related food poisoning and toxic shock syndrome,respectively.,8/3/2023,Food poisioning,69,8/3/2023,Food poisioning,70,Toxic schock syndrome toxin causes 75%of toxic shock syndrome cases reported.Superantigens stimulate T-cells nonspecifically,causing the release of large amounts of cytokines.The cytockines are responsible for the toxic chock syndrome symptoms.,S.aureus produces two types of superantigens,enterotoxins and toxic shock syndrome toxin.,8/3/2023,Food poisioning,71,Food poisoning mechanism,小肠粘膜adenylate cyclase：ATP cAMP肠毒素 小肠粘膜guanylate cyclase：GTP cGMP 细胞分泌功能改变Na+、H2O的吸收抑制与Cl-分泌亢进Na+、Cl-、H2O在肠腔潴留腹泻吸收入血 到达中枢神经系统刺激呕吐中枢 呕吐,Enterotoxins：Typical Toxic type food poisoning,8/3/2023,Food poisioning,72,Clinical Manifestation,潜伏期短：24小时恶心，反复呕吐，上腹部腹泻体温正常或低烧儿童对肠毒素比成人敏感，发病率高，病情重预后一般良好,8/3/2023,Food poisioning,73,S.aureus most commonly causes a localized skin infection,although it can also infect the eye,nose,throat,urethra,vagina,and gastrointestinal tract.In addition,S.aureus can cause more serious ailments when it enters the bloodstream,such as pneumonia,osteomyelitis,arthritism endocarditis,myocarditis,brain abscesses and meningitis,8/3/2023,Food poisioning,74,Diagnosis,流行病学特点临床表现,Therapy,对症处理，一般不需抗生素,8/3/2023,Food poisioning,75,实验室诊断,以毒素鉴定为主（双向琼脂扩散法和动物试验法）提取中毒食品中的肠毒素，确定型别分离中毒食品、患者呕吐物或粪便中的葡萄球菌及其肠毒素与型别不同患者呕吐物中检出葡萄球菌及同一型别肠毒素判定原则：符合实验室诊断三项之一者，即可判定,8/3/2023,Food poisioning,76,Prevention:防止污染与肠毒素的产生,1.避免人对食品的 污染2.避免患乳房炎的奶牛对奶的污染3.奶极其制品从生产至销售全过程的严格管理4.低温冷藏,8/3/2023,Food poisioning,77,Clostridium botulinum肉毒梭菌食物中毒,8/3/2023,Food poisioning,78,芽孢杆菌科（Bacillaceae）、G+粗短杆菌，可形成芽孢，按其外毒素（exotoxin）抗原性可分为A、B、C、C、D、E、F、G 8个血清型 专性厌氧，适温3037，1555与pH4.59.0下繁殖并可产生毒素。芽孢可耐湿热1005h或干热1805min或高压蒸汽12130min，对营养条件要求不高，自然界分存广泛，在土壤中半永久性生长。,1Pathogeny,8/3/2023,Food poisioning,79,Botulinum toxin,形成于胞浆，菌体死亡自溶释放毒素复合体 小肠胰蛋白酶神经毒素解离吸收入血 botulism,热不稳定,7585，515min 100，1min,胃酸及酶不能消化分解,Each neurotoxin consists of a 2 chain polypeptide linked by a disulfide bond as demonstrated in this picture.The larger polypeptide,called the heavy chain,is identical for all 7 toxin types.The smaller polypeptide,called the light chain,varies for each toxin subtype.,神经毒，毒性为KCN的10000倍对人致死剂量：10-6g/kg.bw,8/3/2023,Food poisioning,80,Botulinum toxin structure(schematic diagram),8/3/202