PRRS Epidemiology 蓝耳病流行病学 Professor Mo 莫教授 Bob Morrison DVM, MBA, PhD College of Veterinary Medicine University of Minnesota 鲍勃 莫里森, 兽医博士, 工商管理硕士美国明尼苏达大学兽医学院
PRRS Control 蓝耳病防控 Most important pathogen in North America 在北美地区最重要的病原体 $664 million / year to industry (Holtkamp et al., 2013) 行业一年损失 6.64 亿美元 As single agent in sow herds and as part of respiratory disease complex in growing pigs 母猪群中的单一病原, 生长猪中呼吸道疾病病原的一部分 Prevention 预防 Gilts, pigs, semen 后备母猪, 仔猪, 精液 Location 地点 Fomites including equipment, people, transport 污染物包括包括设备, 人员, 运输
猪健康监测项目 Number herds 猪群数 PRRS 蓝耳病 PED 流行性腹泻 739 998 Number sows 母猪数量 1,989,526 2,533,262
Incidence has decreased 发病率下降报告猪群新感染率蓝耳病每周累积发病从 2009-2016 年 7 月 1 号起累积统计
Repeatable incidence pattern 疾病复发规律 图表 5-PED EWMA 2009-2016 年度分析
Twice the number of cases in the cluster than would have been expected due to chance alone 由于偶然性, 集群中病例数比预期高达两倍
Within herd control 猪群内防控 Classification of sow herds: 母猪群分类 : Stage 1 Infected, shedding virus 阶段一 感染, 散毒 Stage 2 Stable; virus not detected in weaned pigs 阶段二 稳定 ; 在断奶仔猪中未检出病毒 2 fvi stable with live, field virus exposure in gilts 2 fvi- 稳定, 活野毒在后备母猪中感染 2 vx stable with modified live vaccine virus in gilts & sows 2 vx- 稳定, 经产母猪和后备母猪中有修饰的活疫苗病毒 Stage 3 Provisionally negative 阶段三 暂时阴性 Stage 4 Negative 阶段四 - 阴性 Objective is to wean negative pigs: 目标是得到断奶阴性猪 Load / Close / Expose 装猪 / 封群 / 感染 Load at least 20 weeks, possibly with off-site breeding project. 装载 - 至少 20 周, 有可能异地繁殖 Expose 感染 Live, field virus 活野毒 Modified live vaccine virus 修饰的活疫苗病毒
Prevalence decreases as PRRSv is eliminated from sow herds 随着蓝耳病病毒从母猪群消除, 患病率下降 从 2009 年 7 月开始猪群感染状态猪群比率
Great variability of TTNP 恢复正常生产时间差异很大 LVI vs MLV Intermittent pattern of PRRSv-detection by PCR 蓝耳病毒的间歇规律 PCR 检测 Linhares, Cano, Torremorell & Morrison 9
200 days was not enough to achieve stable for ~half of the herds: 200 天 对一半猪群实现稳定状态是不够的 累积 TTNP- 所有农场 84 days 畜群接种后周数 84 天 200 天 200 days 300 天 300 days Linhares, Cano, Torremorell & Morrison 10
Why is TTS so variable? 为什么达到稳定的时间如此多变? Shorter time to stable: 较短的时间达到稳定 Whole herd exposure with LVI (vs vaccine) 整个猪群活毒接种 ( 与疫苗相比 ) Herds had exposure within last 3 years 猪群过去 3 年感染 Herds did not hold pigs back at weaning 猪群在断奶期间无影响 Herds were serviced by a certain vet clinic 猪群是由某个兽医诊所服务
Much shorter TTS is possible 更短的达到稳定时间是可能的 Sows infected and virus crosses placenta 母猪感染, 病毒通过胎盘 After _?_ weeks, litters are born virus negative? 周后, 新生仔猪生来病毒阴性 Aggressive biosecurity to stop lateral spread 积极的生物安全措施阻止横向扩散 0 weeks 0 周 20 weeks( 周 ) 27 weeks( 周 ) 52 wks( 周 ) Outbreak 爆发 1 turn 转化 median 中度 95% sows 母猪 stable 稳定 stable 稳定
Within herd control 猪群内防控 Biosecurity between litters 窝之间的生物安全 Fostering 寄养 People and handling pigs 人员和猪的处理 Processing & injections 接猪和注射 No holding pigs back 不对猪产生影响
My recommendations Sow herds 我的建议 - 对母猪群 Low risk herds 低风险猪群 Biosecurity to prevent infection 生物安全来防止感染 Vaccinate if warranted 如果确定的话使用疫苗 Medium / high risk sow herds 中度 / 高风险母猪群 Vaccinate whole herd quarterly, not continuously 每季度普免, 而不是持续做 Anticipate 2-5% increase abortions 预期 2-5% 流产率增加 Have a plan for intervention 要有干预计划 Monitor to get back to desired status at weaning 进行观察监测以回到断奶时理想状态 Opportunity for batch farrowing? 成批分娩的机会?
Growing pigs 生长猪 Vaccinate: 接种疫苗 PCV-2 圆环 M hyo 支原体 PRRS if sow herd is infected or pigs are likely to be infected 蓝耳病, 如果母猪群已感染或猪易被感染 Which vaccine? Commercially available with trial data on effectiveness. 哪种疫苗? 有实验数据证明有效的的商业疫苗
A story of 2 neighboring herds 关于 2 个相邻猪群的故事
What drives health in growing pigs? 主导生长猪健康的是什么? Sow Herd 母猪群 Genetics 种猪 Sow herd health status (vertical transmission) 猪群健康状态 ( 纵向传播 ) Management decisions eliminate vs control 管理决策 - 消除 vs 控制 Gilt status & acclimation 后备母猪状态和驯化 Vaccination 接种疫苗 Parity distribution 胎次分布 Farrowing room processes 产房流程 Pig quality 猪质量 Wean weight, age and spread 断奶体重, 年龄和分布 Growing Site 生长猪场点 Site management 场点管理 Commingle vs single source 混合 vs 单一来源 Ai Ao vs continuous flow 全进全出 VS 连续流动 Single stock vs over stock 一次装猪 vs 多装 Gender of pigs 猪的性别 Placement strategy to pens 围栏放置策略 Density & health status in region (lateral) 区域密度和健康状态 ( 横向 ) Biosecurity at site (lateral) 场点生物安全 ( 横向 ) Pig care 照理猪 Warm, dry, draft free 温暖, 干燥, 无气流 Identifying, treating and pulling sick / non competitive pigs 识别, 治疗和淘汰病猪 / 非竞争猪 Diet formulation & antibiotics 日粮配方及抗生素 Diagnostics & vaccination 诊断和免疫
Our current research projects and looking ahead 目前研究项目和展望 Expand participation in SHMP 扩大猪健康监控项目范围 Capture management interventions to study optimal strategies 利用管理干预研究最优策略 RFLP 1-7-4 Time to stability and baseline production 达到稳定和生产基线的时间 Time to stability at farrowing 分娩时稳定时间 Real-time risk scoring 实时风险评分 Detect emerging strains of PRRS virus 检测新型蓝耳病毒株