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Instructor: HanSoo JooLecture No. 7 , August 19 13:00-14:30演讲者： 朱汉守第七讲 8月19日 13:00-14:30Enteric diseases in Suckling pigs哺乳仔猪的肠道疾病General Overview概述Definition of Diarrhea腹泻的定义Condition in which the manure changes to a more fluid consistency due to small or large intestine problems.由于大肠或小肠的疾病使粪便含水量增加的情况成为腹泻。Mechanism of Diarrhea腹泻的机制Hypermotility 肠道的蠕动过强The rate of peristaltic motions of the intestine is increased, which increases the evacuation rate of intestinal contents and decreases the time allowed for resorption of water from the intestinal contents. The result is a more fluid stool. 肠道的蠕动节律增加使肠道内容物排空速度增加，进而减少了对肠道内容物水分的重吸收的时间，导致粪便中水分含量增多。Malabsorption 吸收障碍 This occurs when the lining cells of the intestine are damaged and are unable to absorb water or nutrients from the intestinal contents. The result is a more fluid stool, which may contain undigested feed. 这种情况发生在肠道的粘膜上皮细胞受到损伤的时候，粘膜上皮细胞不能够从肠道内容物中吸收水分和营养物质时，导致粪便中水分含量增加，其中常含有未消化的饲料。TGE and rotaviral enteritis lead to malabsorbtion through moderate to severe villous atrophy. 传染性胃肠炎和轮状病毒性肠炎导致小肠绒毛中度到严重萎缩引起营养物质吸收障碍Fecal pH becomes acid with malabsorptive diseases. 吸收障碍疾病使粪便的pH值变低。Hypersecretion 分泌亢进A condition in which the intestinal cells secrete water into the lumen of the intestine at a greater rate than they absorb water from the intestinal contents. The result is a more fluid stool.肠道细胞分泌水分到肠腔的速度大于从肠道内容物吸收的水分的速度，导致粪便含水量增高。Colibacillosis causes diarrhea through hypersecretion. Fecal pH becomes alkaline due to secretion of bicarbonate into the intestinal lumen. 大肠杆菌通过引起分泌亢进而引起腹泻，由于碳酸氢盐的分泌使粪便pH值呈碱性。 Causes of Diarrhea in the Pig引起猪腹泻的病因 Overwhelming exposure to a pathogen 过量接触病原体The presence of a pathogen will not always cause disease, but if the exposure is great enough it will.病原体的存在不一定引起发病，但是与之接触的量过多将引起发病。Diagnosis of Diarrheal Diseases in the Pig猪腹泻病的诊断History病史An explosive onset and rapid spread of disease usually indicates that a virus is involved as the cause of diarrhea. A more insidious onset and slow spread of disease indicates that the cause of diarrhea may be bacterial or parasitic.疾病突然爆发且快速传播暗示腹泻是由病毒引起的，隐伏发作且传播慢表明腹泻可能是由细菌或寄生虫引起的。Other factors that will aid in making a diagnosis are:其它有助于诊断的因素：2929 Age of pigs at onset of disease发病猪的年龄 Percent of litters involved发病的窝数占总窝数的比例 Number of pigs per litter involved每窝发病猪的数量 Morbidity and mortality rates 发病率和死亡率 Progression of the disease in the individual pig 单个猪的发病进程 Type of pigs affected (good doer vs poor doer)感染猪的类型（生长良好的还是生长不良的）Clinical Signs临床症状Small Intestinal Disease 小肠疾病 Dehydration脱水 Vomiting呕吐 Melena-blood in the stool黑粪症粪便中含有血液 Poorly digested food in feces粪便中有消化不良的食物 Diarrhea腹泻Large Intestinal Disease 大肠疾病 Bloody Stools血便 Mucous on feces粪便上附有黏液 Small frequent defecations频繁且少量的排粪 Tenesmusstraining里急后重努责 Diarrhea腹泻General 小结 Pigs with intestinal disease do not always have diarrhea.患肠道疾病的猪不一定腹泻 Consistency and color of the stools will vary with the diet fed. The color of the manure is not diagnostic of a particular diarrheal disease.粪便的浓度和颜色随着所进的食物而改变，不能凭粪便的颜色来诊断特定的腹泻性疾病Necropsy Findings 剖检所见Stomach Contents 胃内容物 Empty stomach胃空虚- Colostrum deprived pig猪初乳摄入不足- Chronic disease state慢性疾病状态 Full stomach胃充盈- Rule out hypoglycemia排除低血糖症- Confirms that sow is milking 确定母猪有泌乳- Indicates acute onset of disease表明疾病的急性发作Lacteals in the mesentery肠系膜乳糜管 Full lacteals充满乳糜 Intestine is able to absorb fat肠道有吸收脂肪的能力 Colibacillosis大肠杆菌病 Empty lacteals乳糜管空虚- Intestine cannot absorb fat肠道不能吸收脂肪- Common with villus atrophy 通常伴有肠绒毛萎缩- TGE and variable with Rotavirus 传染性胃肠炎，可能伴有轮状病毒- May indicate the pig is not nursing- 可能表明猪没被饲养好Serosal surface of the intestine 肠道的浆膜表面 Red/Congested发红/充血 Possible Clostridial Infection 可能是梭菌的感染 Transparent透明状的 Possible TGE可能是传染性胃肠炎Mucosal surface of the intestine 肠道的粘膜表面 Petechial or frank hemorrhage淤血点或明显的出血 Clostridium梭菌 Salmonella沙门氏菌 Fibrinonecrotic membrane纤维素性坏死性伪膜- Clostridium梭菌- Coccidiosis球虫病 Hemorrhagic出血性的- Clostridium梭菌- Swine Dysentery猪痢疾Laboratory Confirmation实验室确证 Isolation and Identification分离和鉴定 Serologic evidence of the pathogen病原的血清学证据Treatment 治疗Bacterial Diarrhea细菌性的腹泻 Antibiotics (Inject., water, feed)抗生素（注射、饮水、伴料） Steroids类固醇 Atropine阿托品 Electrolytes电解质Viral Diarrhea病毒性腹泻 Supportive therapy - change environment支持疗法改变环境 Immunizations免疫Prevention预防Decrease exposure to the pathogen 减少与病原体的接触 Thorough cleaning of facilities彻底清洗用具 Closed herd policy biosecurity封群措施生物安全性 Animal hygiene动物的卫生Increase immunity to disease 增加对疾病的免疫性 Passive Immunity被动免疫 Ensure adequate colostrum intake确保摄入足够的初乳 Ensure adequate milk intake 确保摄入足够的乳汁 Antiserum and antitoxin use 使用抗血清和抗毒素 Hyperimmunize sow超免疫母猪 Active Immunity主动免疫 Pathogen exposure (TGE)接触病原体（传染性胃肠炎） Bacterin and vaccine use (inject/oral)使用菌苗和疫苗（注射/口服）Decrease environmental stress减少环境的应激 Buildings must be clean, dry, warm, and free of drafts. 建筑物必须清洁、干燥、温暖和通风良好 Provide good availability of milk.提供足够的母乳 Maintain correct effective environmental temperatureEET维持适宜的有效环境温度EFTENTERIC COLIBACILLOSIS (NEONATAL DIARRHEA)肠道大肠杆菌病（新生仔猪腹泻）EtiologyEscherichia coli (E. coli)病因学 埃希氏大肠杆菌（E. coli）gram negative bacteria革兰氏阴性菌 Flagellar H Antigen鞭毛“H”抗原 Pili-adherence“K” Antigens 表面“K”抗原Somatic O Antigen菌体O抗原Serotypes 血清型 At least 160 O antigen variations至少160种“O”抗原变异株 4 K antigens account for 95% of the pathogens in the U.S.在美国 4种“K”抗原占据了大肠杆菌K抗原的95 K88 (F4); K99 (F5); 987 P (F6); F41987 and F41 chromosomal DNA987 和 F41 染色体DNAK88 and K99 plasmidsK88 和 K99质粒K88 baby pigs and postwean (no age susceptibility)K88 感染幼仔猪和断奶后仔猪（无年龄易感性）K99, F41, 987P only baby pigsK99, F41, 987P 仅感染幼仔猪some new plasmid encoded一些新编码的质粒antigensF42, neonatal pigs抗原 F42 ，新生仔猪 F165, 1-3 wk old strains, have no toxin F165,13周龄 菌株，没有毒素Pathogenic E. coli release enterotoxins that result in increased mucosal secretion of bicarbonate and sodium and therefore leakage of water into the lumen of the intestine. 致病性大肠杆菌释放肠毒素使肠粘膜分泌碳酸氢盐和钠增加，因此使组织中的水分渗漏到肠腔里。 Two Types:两种类型： enterotoxins-no histological damage 肠毒素无组织学损伤 cytotoxins-cell lysis细胞毒素细胞溶解Enterotoxins肠毒素 Heat Labile Toxin (LT)不耐热的毒素- similar to cholera in humans 与人类的霍乱相似 - activates cyclic AMP 刺激cAMP产生 Antigenic抗原性- Produced by some, not all, pathogenic strain由一些致病性的菌株产生，但不是所有的都能产生- 2 heat stable toxins (ST) Sta (StI) and Stb (StII) 2种耐热毒素（ST）Sta (StI)和 Stb (StII)- Weakly antigenic抗原性弱- Produced by all pathogenic strains except F165除F165外，所有的致病菌株都能产生Cytotoxin:I and II细胞毒素：I 和 IIVerotoxin:(Mostly edema disease)志贺样毒素：（大部分与水肿病有关）Adhesion附着The ability to adhere to intestinal lining is due to the pili, which are present on all enteropathogenic strains.对肠上皮细胞的附着能力依赖于纤毛，所有的肠致病菌株都有纤毛抗原Enteropathogenic (ETEC) Strains (neonatal strains)肠致病性(ETEC)菌株（新生的菌株） Classically典型的: 08, 09, 020, 064, 0101, 0147, 0149 or 0157F4Lt and Stb Lt 和Stbrecently more新近发现的:08,09,064,0101 F5, F6, F41 Sta Recent decrease in F4 strains may be due to pressure from vaccination, or geneticsF5 receptors decrease with age of pig, F6 receptors in mucus increase with age, causing interference. Therefore, both F5 and F6 strains decrease with age of pig.近来F4菌株的减少可能是由于疫苗的抑制作用所致，或者是遗传方面的原因，随着年龄的增加F5受体减少，而粘液中F6受体增加，引起相互的干扰。因此，随着猪年龄的增加，F5 和 F6菌株都减少。ETEC strains in weaned pigs断奶仔猪肠致病性菌株08, 0138, 0139, 0141, 0147, 0149 or 015708, 0138, 0139, 0141, 0147, 0149或0157F4, 2134 P, Lt and Stb (classical O groups)F4, 2134 P, Lt和 Stb (经典的O抗原组)Stb, Sta and VT (0138, 0139 and 0141)Stb, Sta 和 VT (0138, 0139和 0141)no adhesions in the latter后者无黏附能力Attaching - Effacing E. coli (AEEC)黏附涂抹型大肠杆菌(AEEC) Mostly 045主要为O45 New, rare disease新发的、少见的疾病 Colonization of mature enterocytes定植于成熟的肠细胞 Effacement of microvilli小肠微绒毛脱落 Enterocyte degeneration肠细胞变性 Inflammation of lamina propria肠固有层炎症Epidemiology流行病学 Pigs are infected after birth via oral or umbilical routes. 仔猪出生后经消化道或脐带感染 Most sows carry the organism.大多数的母猪携带病原体 The organism will survive in dirty environments此病原体易在污脏的环境里存活Pathogenesis发病机制 Environmental Temperature环境温度- Low temperatures cause decreased peristaltic rate.低温会导致肠蠕动率降低- Pathogenic E. coli is not flushed from GI tract. 致病性大肠杆菌在胃肠道里活力不强- Pathogens multiply in sufficient number to cause disease.病原体繁殖到足够的数量才能引发疾病Clinical Signs临床症状 In the Unweaned Pig (Neonatal Diarrhea)在未断奶的仔猪（新生仔猪腹泻）- 50% of all scours in 1st week of life = E. coli仔猪1周龄以内，有一半的腹泻大肠杆菌- Time of onset = birth to about 8 wks发病时间从出生至大约8周龄- Most common from 0 - 7 days多发生于07天- Dehydration脱水- Diarrhea腹泻- Sudden death (with or without diarrhea)猝死（有或无腹泻）- Morbidity can be low or high and tends to become higher the longer the farrowing house has been in use.发病率可高可低，而且有一个趋势：产房使用的时间越长，发病率就越高- Case fatality can be very high if pigs are not treated. 如果不进行治疗，死亡率会很高- May be more severe in litters from gilts and poor milking sows. 后备母猪和产奶不足的母猪产下的窝次发病可能更加严重- Pigs may or may not have manure-stained perineum. Each pig in a litter must be picked up and examined carefully. Slight abdominal pressure may help to see scours.猪的会阴部有或无粪便污染，要认真检查窝内的每一头小猪，轻压腹部可帮助发现腹泻。- Scours may be visible on the floor, but this is difficult with wire floors.腹泻的粪便可以在地板上看见，但是在铁丝网做的地板上很难发现。 Weaned Pigs (Post weaning Diarrhea)断奶仔猪（断奶后腹泻）- High morbidity/low mortality高发病率/低死亡率- Diarrhea (green-brown)腹泻（棕绿色）- Dehydration脱水- Anorexia食欲减退- Piling打堆- Morbidity can be very high发病率可以很高- Case fatality is usually lower than in the baby pig死亡的病例通常比幼仔猪低- Most often occurs about 5 to 14 days post weaning大部分常发生于断奶后514天Necropsy Findings 剖检所见 No pathognomonic gross or microscopic lesions无特征性的肉眼或显微病变 Fluid distension of small intestine小肠因充满液体而膨胀 Undigested milk curd in stomach胃内有未消化的乳凝块 Sometimes intestinal hemorrhage有时肠道出血 Villous atrophy may be present 可能存在肠绒毛萎缩 White lacteals白色的乳糜管Diagnosis诊断 Clinical signs and history临床症状和病史 Isolation of pure E. coli from jejunum从空肠里分离纯大肠杆菌 Characterization of strain菌株的特征- serotyping血清型鉴定- monoclonal antibodies单克隆抗体- DNA probesDNA探针 Alkaline pH of feces粪便的pH值呈碱性 Do an antibiotic sensitivity做药敏试验 Be aware that mixed infections often occur要意识到常常会发生混合感染Hemorrhagic Gastroenteritis出血性胃肠炎 Pigs at weaning, rare断奶仔猪，少见 Sudden death猝死 Mucosal congestion, stomach hemorrhage肠粘膜充血、胃出血 Strains: 0149:K91, 0157:KV17 and 08:K4627菌株：0149:K91, 0157:KV17 和 08:K4627 F4, Stb and Lt (rarely VT)F4, Stb 和 Lt (VT罕见)Septicemia败血症 Young pigs, very common in SEW systems幼仔猪，早期隔离断奶非常普遍 Capsulated, aerobactin + strains芽孢化，产气菌毒素菌株 078:K80; 0115: KV165; 04:K98 Adhesion F165 (good marker)黏附素F165（好的标记物）Treatment治疗 Unweaned Pig - Treat entire litter with antibiotics 哺乳仔猪整窝抗生素治疗- Apramycin阿泊拉霉素- Amikacin丁氨卡那霉素（阿米卡星）- Gentamicin 庆大霉素- Neomycin新霉素- Trimethoprim SulfaTMP加磺胺类药剂- Corticosteroids and Atropine may be useful皮质类固醇和阿托品可能有效- Oral antiserum at birth? 在出生时口服抗血清？ Weaned Pig - Treat the entire group or pen with antibiotics.断奶仔猪用抗生素对整窝或整圈仔猪进行治疗 - Injectables if severe 如果严重就用注射制剂- Water medication is probably best 饮水加药可能效果最好- Feed medication as a preventative饲料里拌药作为预防Prevention预防 Good hygiene will reduce the number of organisms in the environment. Increase the pigs immunity.良好的卫生可以减少环境中微生物的数量，增强猪的免疫力- Decrease humidity降低湿度- Acidify water酸化饮水- Hyperimmunize sows with:Injectable bacterins加强免疫母猪： 注射菌苗2 and 4 weeks prefarrowing (best)在产前2和4周（最好）- Pigs will receive antibodies from the sow in the colostrum and the milk. 仔猪将从母猪的初乳和乳汁里获得抗体- Must ensure proper milk supply to pig for effective passive immunity.为了获得有效的被动免疫力必须确保有足够的乳汁供应给仔猪- Feeding K88 ent- strains at weaning may work through competitive exclusion 在断奶时饲喂K88 ent- 菌株可通过竞争作用减少病原菌的繁殖- Bacterins for post weaning scours (active immunity) are mostly ineffective.大多数情况下，菌苗（主动免疫）对断奶后腹泻无效- Bacterins will result in the appearance of non-classical adherence factors and increased postweaning diarrhea菌苗会导致“非典型”附着因子出现从而增加了断奶后仔猪的腹泻B subunit (LT toxin)Future bacterins: B亚单位（LT毒素）未来的菌苗or或Pili + B subunit菌毛B亚单位 Reduce stress on the pig.*Draft-free/warm/dry降低猪 的应激 *通风良好/温暖/干燥 Differentials鉴别诊断- TGE-more acute onset, higher mortality, vomit传染性胃肠炎发病更急，死亡率更高并有呕吐- Clostridial Enteritis-more acute, blood in feces frequently present-organisms visible in a Gram stain.梭菌性肠炎 发病更急、血便经常出现用革兰氏染色可清楚地看见病原体 SUMMARY总结COLIBACILLOSIS大肠杆菌病 Enterotoxigenic strains of E. coli from K88, K99, 987P or F41 pili大肠杆菌的肠毒性性菌株来自K88, K99, 987P 或F41菌毛 Piglets are affected the first week of age仔猪在1周龄感染 Yellow, watery diarrhea, piglets are stunted, do not grow黄色、水样腹泻、仔猪生长受阻、生长停滞 Mortality is variable but can be high死亡率不等但可能很高 Alkaline pH in the feces粪便呈碱性 No obvious macroscopic or microscopic lesions没有明显的肉眼或显微镜下的病变 Treatment with antibiotics (gentamycin) and electrolytes will save some pigs抗生素（庆大霉素）和电解质治疗可挽救一些猪 Acidification of water is also useful酸化的饮水也有帮助 Vaccination of pregnant sows with a pilus vaccine is a must in a control program怀孕母猪接种含菌毛抗原的疫苗对于控制本病是必要的CLOSTRIDIAL ENTERITIS (NECROTIC ENTERITIS)梭菌性肠炎（坏死性肠炎）Etiology病因学 Clostridium perfringens type CC型产气夹膜梭菌 Gram positive encapsulated anaerobic bacillus革兰氏阳性、有芽孢的厌氧杆菌 Produces alpha and beta major toxins主要产生和毒素 Protease-most important 蛋白酶最重要 Beta = - Trypsin sensitive-colostral antitrypsin activity helps the toxin毒素对胰岛素敏感抗胰蛋白激酶能帮助毒素发挥作用Epidemiology 流行病学 Enzootic in North Central U.S. - not very common nowadays在中北美呈地方性流行现在不常见 First week of life usually - can be older 1周龄内多发1周龄以上也可能发病 Morbidity varies发病率不等 Case fatality extremely high 死亡率非常高 Pigs ingest organisms 猪经消化道感染 Becomes endemic in herds猪群呈地方性流行 Has become a rare disease已经比较少见Pathogenesis 发病机理 Bacteria attaches to intestinal villi细菌附着在肠绒毛上 Necrosis of intestinal lining 肠粘膜上皮坏死 Hemorrhage in acute cases 急性病例出血 Emphysema of gut wall 肠壁气肿 Lethal-Beta toxin致死因子毒素Clinical Signs 临床症状 Peracute-Die within 24 hours最急性型 24小时内死亡- hemorrhagic diarrhea- 出血性腹泻 Acute-Die in 2 to 3 days急性型 2至3天内死亡- reddish brown liquid feces 红褐色水样粪便- feces may contain necrotic debris粪便可能含有坏死碎片 Subacute-Die in 5 to 7 days亚急性型 5至7天死亡- persistent diarrhea - no blood- 持续腹泻不带血 Chronic-Chronic poor doing pigs慢性型 猪慢性的生长不良Necropsy Findings 剖检所见 Peracute-Dark red jejunum最急性型 空肠呈暗红色- Blood-filled lumen 肠腔充满血液- Necrotic mucosa 肠粘膜坏死- Emphysema in G.I. lining胃肠道上皮气肿 Acute-Less hemorrhage急性型 出血量较最急性型少- More necrosis坏死更严重- Emphysema in G.I. lining胃肠道上皮气肿 Subacute-Necrotic membrane亚急性型 坏死性伪膜 Chronic-Firmly adhered necrotic membrane - difficult to diagnose can confuse with coccidiosis慢性型 坏死性伪膜膜与上皮紧密粘连与球虫病易混淆难于诊断Diagnosis诊断 Clinical signs临床症状 Necropsy signs剖检所见 Microscopic lesions显微病变 Demonstrate clostridia in the intestine在小肠里找到梭菌 Ten (10) clostridia per microscopic oil immersion field 每个油镜视野下有10个梭菌 Culture细菌培养Treatment治疗 Antibiotics (not very effective) Penicillin, Tylosin, etc. 抗生素（无特效）青霉素、泰乐菌素等 Antitoxin抗毒素 Supportive therapy-intraperitoneal fluids辅助治疗腹膜内输液Prevention预防 Passive immunization of pigs被动免疫猪群 Give Clostridium. antitoxin at birth, 5 and 7 days of age 在刚出生、5和7日龄分别给予梭菌抗毒素 Hyperimmunize sows with Clostridium. Toxoid用梭菌类毒素超免疫母猪 Ensure proper milk ingestion prefarrowing确保母猪产前的营养物质摄入，从而保证其有足够的乳汁分泌 Toxoid to weaned pigs if necessary如果必要可给予断奶仔猪类毒素 Sanitation卫生 BMD to sows用亚甲只柳酸枯草菌素（BMD）饲喂母猪Differentials鉴别诊断 Coccidiosis-no blood, lower mortality, no clostridia 球虫病不出血、死亡率较低、无发现梭菌 visible-necrotic membranes in intestine may be confusing 明显肠道内坏死性假膜可能易混淆 E. coli-no blood, lower mortality, culture of the E. coli from intestine 大肠杆菌病不出血、死亡率较低、从小肠内容物中可培养出大肠杆菌 Clostridium pefringens Type AA型产气夹膜梭菌 Presents during day 1-2 of life12天龄发病 Brown, “sticky” diarrhea棕色、粘性的腹泻 10-20% morbidity throughout farrowing group仔猪发病率1020 Minimal mortality死亡率低 Colonic edema结肠水肿 Treatment: ml Tylosin 200/day 1 of life治疗：0.5ml泰乐菌素200/ 1天龄Clostridium perfringens Type C C型产气夹膜梭菌 Causal agent is C. perfringens Type C病原是C型产气夹膜梭菌 Affects baby pigs in the first week of age1周龄的仔猪易感 Bloody diarrhea, stunting and high death loss出血性腹泻、生长缓慢和高的死亡率 Necropsy shows blood and congestion in the small intestine剖检可见小肠内出血和充血 Only bloody intestinal disease of baby pigs仅仔猪表现为出血性肠道病变 Treatment with antibiotics is not very effective抗生素治疗无特效 Control includes passive immunization of baby pigs with antiserum and vaccination of pregnant sows控制：用抗血清对仔猪被动免疫和对怀孕母猪进行接种疫苗COCCIDIOSIS 球虫病Etiology病因学 Eimeria species are not involved不感染艾美尔球虫 Isospora suis is the pathogen病原体是猪等孢球虫 Severity depends on numbers of oocysts ingested 严重的程度由摄入卵囊的数量决定 Reproduces in distal third of small intestine在小肠的后三分之一段繁殖Epidemiology 流行病学 Affects young pigs-7 to 11 days old-time for the merozoite to develop 仔猪感染7至11天龄 裂殖子在这段时间里形成 Recently outbreaks in older animals (4-7 wks of age)最近在稍大点猪群中也有爆发（47周龄） Older animals are carriers较大的猪是病原携带者 Sporulation necessary for infectivity孢子的形成对感染是必须的 Sows are not the major source of oocysts 母猪不是主要的卵囊来源 Source of oocysts = environmental contamination-oocysts are very resistant, especially in wood surfaces 卵囊来源环境的污染卵囊有很强的抵抗力，尤其是在木头表面 Pigs ingest the oocysts猪摄入卵囊Pathogenesis 发病机理 Parasite reproduces in the intestinal cells 寄生虫在肠道上皮细胞内繁殖 Cells rupture when oocysts are released卵囊释放导致细胞破裂 Intestinal lining is damaged肠道内皮受损 Sows are not carriers母猪不是病原携带者Clinical Signs临床症状 7- to 21-day-old pigs are affected 7至21日龄的猪感染 Very restricted age distribution分布的年龄段非常窄 Diarrhea腹泻 Emaciation-fuzzy pigs消瘦 Stunting生长迟缓 Moderate morbidity-moderate mortality温和的发病率和死亡率Necropsy剖检 Acute enteritis-distal jejunum and ileum-turgid and thickened 急性肠炎空肠后段和回肠肿胀和增厚 Dull granular mucosa progresses to necrotic mucosa 粘膜色暗有颗粒，进而发展为粘膜坏死 Yellow fibrinone
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