The Pirbright Institute, Surrey, UK.
Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
Transbound Emerg Dis. 2020 Jul;67(4):1532-1542. doi: 10.1111/tbed.13487. Epub 2020 Feb 4.
This study investigated the potential of pooled milk as an alternative sample type for foot-and-mouth disease (FMD) surveillance. Real-time RT-PCR (rRT-PCR) results of pooled milk samples collected weekly from five pooling facilities in Nakuru County, Kenya, were compared with half-month reports of household-level incidence of FMD. These periodic cross-sectional surveys of smallholder farmers were powered to detect a threshold household-level FMD incidence of 2.5% and collected information on trends in milk production and sales. FMD virus (FMDV) RNA was detected in 9/219 milk samples, and using a type-specific rRT-PCR, serotype SAT 1 was identified in 3/9 of these positive samples, concurrent with confirmed outbreaks in the study area. Four milk samples were FMDV RNA-positive during the half-months when at least one farmer reported FMD; that is, the household-level clinical incidence was above a threshold of 2.5%. Additionally, some milk samples were FMDV RNA-positive when there were no reports of FMD by farmers. These results indicate that the pooled milk surveillance system can detect FMD household-level incidence at a 2.5% threshold when up to 26% of farmers contributed milk to pooling facilities, but perhaps even at lower levels of infection (i.e., below 2.5%), or when conventional disease reporting systems fail. Further studies are required to establish a more precise correlation with estimates of household-level clinical incidence, to fully evaluate the reliability of this approach. However, this pilot study highlights the potential use of this non-invasive, routinely collected, cost-effective surveillance tool, to address some of the existing limitations of traditional surveillance methods.
本研究探讨了混合奶作为口蹄疫（FMD）监测的替代样本类型的潜力。每周从肯尼亚纳库鲁县的五个混合设施收集的混合奶样本的实时 RT-PCR（rRT-PCR）结果与家庭层面 FMD 发病率的半月报告进行了比较。这些针对小农的定期横断面调查旨在检测家庭层面 FMD 发病率为 2.5%的阈值，并收集了牛奶产量和销售趋势的信息。在 219 份牛奶样本中检测到 9/份 FMD 病毒（FMDV）RNA，使用特定类型的 rRT-PCR，在这 9 份阳性样本中鉴定出 3/份血清型 SAT 1，同时伴有研究区域的确认暴发。在至少有一名农民报告 FMD 的半月期间，有 4 份牛奶样本呈 FMDV RNA 阳性；即，家庭层面的临床发病率高于 2.5%的阈值。此外，当农民没有报告 FMD 时，一些牛奶样本呈 FMDV RNA 阳性。这些结果表明，当多达 26%的农民向混合设施提供牛奶时，混合奶监测系统可以在 2.5%的阈值下检测到 FMD 家庭层面的发病率，但可能甚至在感染水平较低（即低于 2.5%）时，或者当传统疾病报告系统失败时。需要进一步研究以建立与家庭层面临床发病率估计值的更精确相关性，以充分评估这种方法的可靠性。然而，这项试点研究强调了这种非侵入性、常规收集、具有成本效益的监测工具的潜在用途，可以解决传统监测方法存在的一些局限性。
