我国蓝耳病的流行情况及防控策略 Epidemic situation of PRRS in China and the control strategy 报告人 : 周磊 Presenter: Lei Zhou leosj@cau.edu.cn 中国农业大学动物医学院 CVM of China Agricultural University
报告主要内容 Main contents 1. 猪场蓝耳病的发病特征 Pathogenic characterization of PRRS in pig farms 2. 我国蓝耳病当前流行趋势 Epidemic situation of PRRS in China 3. 猪场蓝耳病防控策略 Control strategy of PRRS
蓝耳病的病原 Pathogen of PRRS 病原为猪繁殖与呼吸综合征病毒 (PRRSV) Porcine reproductive and respiratory syndrome virus 基因型 (Genotypes): 欧洲型 (Genotype 1) 北美型 (Genotype 2) PRRSV 高致病性毒株 田间野毒 Highly pathogenic strains Field strains 低致病性毒株 Low pathogenic strains 田间野毒 Field strains 减毒的疫苗毒 MLV derived strains Fields Virology, P17111 (bar = 27 nm)
猪场蓝耳病发病特征 Pathogenic characterization of PRRS in pig farms
临床症状 Clinical symptoms 急性型 (Acute) 厌食 嗜睡 发热 Anorexia, drowsiness, fever 呼吸困难和急促症状 Dyspnea and respiratory disorder 引起母猪的繁殖障碍 ( 早产 死胎 木乃伊, 弱胎 ) Reproductive disorders in sow (premature birth, stillbirth, mummies) 死产率可达 35% 以上, 木乃伊可达 25% Stillbirth rate of up to 35%, mummies up to 25% 母猪在末期繁殖性能指标恢复, 但仔猪或生长猪仍有不同程度的呼吸系统症状存在 Sow reproductive performance recoveries earlier than respiratory disorder in piglets
慢性型 (Chronic) 繁殖型症状可恢复到正常水平 Reproductive failure can be restored to normal levels 其所产仔猪的活仔率会下降 Survive rate of litters can decline 亚临床型 (Subclinical) 临床症状不明显 No obvious clinical symptom 可检测到血清学抗体阳性 Serologically positive for PRRS
非典型型 (Atypical) 又称严重型 PRRS Severe type of PRRS 由 HP-PRRSV 引起 Caused by HP-PRRSV 母猪流产 死亡 ( 死亡率 >5%, 流产率 >10%) Sow abortion and death (mortality >5%, abortion rate >10%) 不同经产数及妊娠阶段的母猪都出现流产症状 Abortion for sows in all parities and all stages 仔猪 生长育肥猪出现高热 (>41 ) High fever for piglets and grower-finisher pigs (>41 ) 高发病率 高死亡率 ( 可至 100%) High mobility and high mortality (up to 100%)
主要病理变化 Major pathogenical lesions 大体病变 Gross lesions 肺弥漫性间质性肺炎 Diffused interstitial pneumonia 肺脏充血 出血 Congestion and bleeding of lung 淋巴结水肿出血 Edema and bleeding of lymph node
显微病变 microscopic lesions 严重时表现为肺脏显微结构完全消失 The microstructure of alveolar septa may disappear in some severe cases 严重出血 Severe bleeding 小叶间隔增厚 大量的炎性细胞及坏死细胞碎片浸润于肺泡腔支气管周围 Alveolar septa was expanded by macrophages, lymphocytes, and plasma cells 卡他性肺炎区 Cardiac Pneumonia 淋巴结 子宫 睾丸 脑 支气管上皮都有不同程度病变 Various degree of lesions on lymph nodes, uterus, testis, brain and bronchial epithelium
显微病变 microscopic lesions HP-PRRSV 急性肺损伤 Acute lung damage in HP-PRRS cases 严重纤维化 Severe fibrosis 更多的单核细胞 中性粒细胞沁润 More monocytes and neutrophils cells expanding Histopathological changes in the lungs 肺泡失去弹性, 呼吸严重受阻 Alveolar loses elasticity, severe respiratory obstruction Fibrosis in the lungs Han et al., Vet. Microbiol 2014
间接危害 Indirect hazard p 共感染和继发感染严重 Severe co-infection & secondary infection ü 与 PCV2 共感染促进 PMWS 产生, 使 PRDC 临床 表现更严重 Co-infection with PCV2, induce PMWS, severe PRDC ü 加重肺炎支原体的临床表现 Increase the severity of clinical presentation caused by M. hyo. ü 传染性胸膜肺炎和副猪嗜血杆菌病 --- 死亡率升高 Secondary infection of App & HPS : increased mortality p 免疫抑制影响疫苗免疫 Immunosuppression limits the vaccination effect of other vaccine ü 影响猪瘟 伪狂犬疫苗的免疫应答 Reduce the immune responds to CSFV and PRV vaccination
传播方式 Transmission 直接接触传播 Direct transmission 鼻腔分泌物 唾液 撕咬打斗 Nasal secretions, saliva,bite and fight 经胎盘传播 Via placenta 母猪传给胎儿 Sow-fetus transmission 经污染物传播 Via fomites 靴子 推车 针头 其他器械 空气传播 ( 气溶胶 ) Airborne (aerosol) 虫媒传播 Insect spreads 公猪精液 Boar semen 常规消毒剂有效 Most disinfectants are effective Clothes, boots, needles and equipment
当前我国蓝耳病流行情况 Current Epidemic situation of PRRS in China
2015-2016 年血清学调查 Serological investigation (Year 2015-2016) 2015 阳性率 66%~95% Positive rate 66%-95% 阴性场 3 个 (303 个场 ) 3 Negative (total 303 farms) 2016 阳性率 80% 左右 Positive rate is around 80% 阴性场 4 个 (390 个场 ) 4 Negative (total 390 farms)
当前田间毒株流行变异情况如何? How about the variation of PRRSV field strains?
毒株多样性 Diversity of PRRSV field strains 人无我有 (HP-PRRSV) China-specific strains (HP-PRRSV) 人有我强 (NADC30-like) Virulence increased strains 同时流行 ( 经典毒株 HP-PRRSV NADC30-like 欧洲型毒株) Simultaneously epidemic (Classic strains, HP-PRRSV NADC30-like, EU strains) 随时变异 ( 各种缺失 插入和基因变异 ) Variation (deletion, insertion and substitution) 重组叠现 ( 野毒 + 野毒 / 疫苗 ) Recombination (field strains+ field strains/vaccine )
我国 PRRSV 毒株 ORF5 遗传演化规律 Phylogenetic analysis of Chinese PRRSV strains based on ORF5 HP-PRRSV 以及致弱疫苗株 HP-PRRSV and derived MLV 国内经典毒株 Classic Chinese strains 类 NADC30 毒株 NADC30-like 美国来源的经典毒株 Classic strains of US
田间毒株多样性 Diversity of field strains 我国 PRRSV 毒株 Chinese PRRSV strains Nsp2 缺失 / 插入模式 Deletion / insertion in nsp2
类 NADC30 毒株开始流行 The emergence of NADC30-like virus 2014 年 Year 2014 CHsx1401 基因组 15020 nt, 与美国 NADC30 毒株亲缘性最近 CHsx1401, genome is 15020nt in length; close to US strains NADC30
Nsp2 氨基酸缺失模式与 NADC30 相同 131-aa deletion in, similar with NADC30 111-aa (323-433)+1-aa (481)+ 19-aa (533-551)
NADC30-like 感染猪场以母猪流产等繁殖障碍为特征, 发病母猪群的流产率可达 30%~40% 左右 NADC30-like virus outbreak is mainly characterized as reproductive disorder, abortion rate up to 30-40% 哺乳仔猪 保育猪和生长育肥猪以呼吸道疾病为主, 猪细菌性继发感染和死淘率增高 Respiratory disease in sucking and grower-finisher pigs, the rate of secondary infection and culling increased 该毒株可在猪场持续存在很长时间, 造成种猪群和生长猪群生产成绩极不稳定 Be persistent in farm, cause unstable productive performance in herd 该毒株极易与我国毒株重组 Easy recombination with other strains
病毒重组 Recombination 不同 PRRSV 共感染导致的重组现象 Caused by co-infection of different PRRSV strains 不同毒株间的重组导致新毒株的产生 Recombination produces new virus JXA1-R TJM 疫苗与类 NADC30 重组 Recombination between NADC30-like virus and vaccine stains, such as JXA1-R and TJM TJnh1501 重组毒的致病性介于介于 HP-PRRSV 和类 NADC30 毒株之间 TJnh1501 is a recombined virus
疫苗对类 NADC30 毒株不能提供有效保护 Limited protection of current vaccine to NADC30-like virus 免疫攻毒组较非免疫对照攻毒组血清中病毒血症下降略快 A little benefit on viremia clearance MLV 对日增重增加有一定效果 BI MLV vaccination provide some effect on DWG 由于与类 NADC30 株的遗传演化关系较远, 目前我国的商用疫苗不具有良好的免疫保护效果 Vaccines provide extremely limited cross-protection efficacy against the NADC30-like virus infection
欧洲型毒株 (Type 1) 零星出现 Sporadic outbreak of Type 1 PRRSV Lelystad virus LV4.2.1 01CB1 EuroPRRSV SD01-08 GZ11-G1 Amervac PRRS SHE BJEU06-1 HKEU16 KNU-07 NMEU09-1 3 Isolates 0.02
怎样防控蓝耳病? How to control PRRS?
控制对策 Control strategy 诊断先行 综合防控 稳定控制 Diagnosis, Comprehensive prevention and keep stable statute 重点防控 HP-PRRSV 感染 Prevent HP-PRRSV infection 生物安全 + 监测 + 免疫管理 + 继发感染控制 Biosecurity + monitoring + vaccination + secondary infection control 综合防控 Comprehensive prevention and control
猪场的生物安全 Biosecurity of pig farms 猪场外部生物安全措施 防止引入 PRRSV 新毒株 Biosecurity from outsides of pig farms blocks importing new strains ü 猪 引种隔离监测 避免引入带毒种猪 Pigs isolation monitoring avoid inducing PRRSV positive pigs ü 人员 隔离 洗澡 更换衣服 鞋 Staff---isolation, shower, changing cloth and shoes ü 运输工具 车辆 物品 清洗 消毒 Vesicles,craft and equipment-----clean and disinfection
做好猪场内部生物安全措施 降低或阻断 PRRSV 在猪场的循 环和传播 猪与猪之间传播 :AIAO, 多点式饲养, 清群 ( 半清群 ) McREBEL 法则 : 出生 24h 以上仔猪严禁寄养,AIAO, 针头控制 猪场人员 猪场设备 器械 注射针头 猪场运输猪工具 人工授精 公猪精液受到 PRRSV 污染 猪场内气溶胶 (120m) 其他 蚊 虫等 Inner biosecurity ----Reduce circulation of resident virus Transmission in herd: AIAO, multi-sites farm, depopulation (semi depopulation) McREBEL system of pig follow management Staff, vesicles,craft, equipment, needles AI---Boar semen contaminated by PRRSV Aerosol 120m Others --- mosquito and other insects
免疫管理 Vaccination PRRSV 减毒活疫苗免疫原则和策略 Strategy of PRRSV MLV utilization 确定目标 : 建立阴性场 阳性稳定场 Aim: Negative Farm or stable farm? 安全性好的活疫苗 个性化的免疫程序 Safe vaccine, personalized program 一个猪场仅使用一种活疫苗 ( 安全第一 ) Only one MLV strain for each farm 猪群稳定后, 应停止使用活疫苗 Can stop vaccination whenprrs is stable 经产且抗体阳性母猪群不用免疫 No need vaccination for PRRSV + sow 后备母猪可在配种前 1-3 月免疫 1 次 Gilt: vaccinate once, 1-3m pre-breeding
PRRS 不同类型猪场的主要控制措施 PRRS 阴性猪场 ( 种猪 ) 不用活疫苗 阳性 / 稳定猪场 不用活疫苗全群免疫 后备猪驯化 Strategies for different kinds of farms PRRSV negative farm(breeding farm)---do NOT use MLV Positive / stable farm---- No need for whole herd vaccination Gilts acclimatization 阳性 / 不稳定猪场 适当使用活疫苗 Positive / unstable farm---- need use MLV 据发病情况提前 3-4 周给生长猪群一次免疫 Vaccinate grower herd 3-4 week before the symptom was observed in last batch
PRRS 不同类型猪场的主要控制措施 Strategies for different kinds of farms 疫情发生猪场 使用活疫苗 合理的免疫程序 PRRSV outbreak farm ---Use MLV, design reasonable program 母猪群 1 次免疫 ( 配种前 ) Sow herd----once vaccination before the breeding 生长猪群 依据感染和发病阶段 ( 经临床和实验室确诊 ), 提前 3-4 周进行免疫, 可免疫 1-2 次 Grower herd---once/ twice vaccination, 3-4 week ahead of the PRRSV infection (base on the clinical symptom and diagnosis results
猪群的继发感染控制 Control secondary bacterial infection 蓝耳病感染猪群药物预防与保健 Antibiotic utilization for prevention and health improvement in PRRSV outbreak herd 发病猪群的继发感染控制 Secondary bacterial infection control 头孢类抗生素 Cephalosporins antibiotics
其他措施 Other methods 闭群饲养 Herd closure 多点饲养 母猪分胎次饲养 Multi-sites production, batch 驯化 (PRRS 阳性猪场 )Acclimatization (PRRS postive farm) 自然感染 ( 阴性后备母猪与经产母猪混群 ) Natural infection (put PRRSV positive sow into PRRSV Negative gilt herd) 活病毒接种 ( 猪场带毒猪血清 ) Virus inoculation (PRRSV positive serum) 减毒活疫苗接种 ( 选择安全的疫苗 ) MLV vaccination (safe vaccine) 独立的驯化舍, 确定抗体转阳, 不再排毒方可混群 Isolated Acclimatization House, PRRSV seropositive, NO virus shielding 尽量只让单一毒株在猪场传播 (Single strain circles in farm)
致谢 Acknowledgements 中国农业大学动物医学院 杨汉春教授 农业部动物流行病学与人兽共患病重点实验室
谢谢大家 Thank You