Hazards Associated with Zoonotic enteric pathogens in Emerging Livestock meat pathways (HAZEL)

背景：来自牲畜(牛、山羊、绵羊和家禽)的肉类是贫穷农民、他们的家庭和社区的主要蛋白质来源。随着国家的发展，人口增长并向城市地区迁移，牲畜系统的性质必须改变，以跟上消费者对肉类的需求。这为可能寻求为商业市场生产肉类的贫穷农民提供了一个经济机会，但也对公众健康构成了潜在威胁。屠宰和加工设施的集中化以及为批发商、零售商和消费者服务的分销网络的增长可能对食源性疾病产生重大影响，因为随着生产系统的扩大和供应链的日益复杂，感染和污染的风险可能会增加。包括沙门氏菌和弯曲杆菌在内的细菌性食源性病原体已经被描述为非洲被遗忘的人畜共患病，肉类供应链的变化可能会加剧这一问题。与此同时，政策、监管制度和技术能力的改进是缓解此类问题的潜在工具。目的和目的：我们的目标是深入了解人畜共患肠道病原体如何在坦桑尼亚的肉食链中流动，并利用这些信息制定改善食品安全的政策。我们把重点放在坦桑尼亚，因为该国已被确定为细菌性食源性人畜共患病的热点，而且该国的国家畜牧政策促进了畜牧生产系统的集约化，以满足日益增长的肉类需求。此外，我们的团队可以在阿鲁沙和乞力马扎罗牲畜密集地区现有的基础设施和实验室能力以及多年的跨学科研究合作的基础上再接再厉。因此，既有必要也有能力进行这项研究。为了实现我们的目标，我们将使用一种称为模块化过程风险建模(MPRM)的方法来描述牲畜肉类的途径和这些途径中的危险。在最初的步骤中，社会和兽医科学家描述了从农场到零售的肉类生产的每个阶段。当地规模的商业生产将与更广泛的市场进行比较，以确定随着肉类生产、加工和分销规模扩大可能出现的危险。一旦绘制了肉类供应链的图表，就可以使用微生物学技术来确定链中每一步是否存在并集中了非伤寒沙门氏菌和弯曲杆菌。通过研究细菌的遗传指纹，可以追踪细菌从收获前到收获后的流动。将牲畜和食品分离株的DNA指纹与从腹泻或其他疾病患者身上获得的细菌分离株的DNA指纹进行比较，将表明肉类在人类疾病中的作用。在绘制新出现的牲畜肉类路径及其相关危险地图的同时，我们将对坦桑尼亚当前的食品安全政策和法规进行正式审查，并评估它们的实施情况。了解现有政策的优势和劣势，再加上通过分析肉类价值链和牲畜肉类途径中的危险确定的机会和威胁，将使科学家和政策制定者能够制定新的食品安全政策。潜在的应用和益处：通过社会、生物和定量科学的结合以及与政策制定者的合作，该项目将有助于改进食品安全政策，减少人们通过食品接触非伤寒沙门氏菌和弯曲杆菌。这将为坦桑尼亚的生产者和消费者社区提供经济和健康方面的好处。此外，产品安全性的提高可能有助于农民进入新的零售市场。最后，在这个项目中开发的方法可以作为其他疾病和国家的模式，在这些国家，畜牧业生产系统的变化可能会影响我们食品的供应和安全。

Context: Meat from livestock (cattle, goats, sheep and poultry) is a key protein source for poor farmers, their families and communities. As countries develop, populations grow and move to urban areas and the nature of livestock systems has to change to keep up with consumer demand for meat. This presents an economic opportunity for poor farmers who may seek to produce meat for commercial markets but it also presents a potential threat to public health. Centralization of slaughter and processing facilities and growth of distribution networks that serve wholesalers, retailers and consumers may have major implications for food-borne diseases because risks of infection and contamination are likely to increase with scaling-up of production systems and increasing complexity of supply chains. Already, bacterial food-borne pathogens, including Salmonella and Campylobacter, have been described as the 'forgotten zoonoses' of Africa and changes in the meat supply chain may aggravate the problem. At the same time, improvements in policy, regulatory systems and technical capacity are potential tools to alleviate such problems. Aims and Objectives: Our aim is to develop a robust understanding of how zoonotic enteric pathogens flow through the meat chain in Tanzania and to use this information to develop policies to improve food safety. We focus on Tanzania because the country has been identified as a hotspot for bacterial foodborne zoonoses and because its National Livestock Policy promotes intensification of livestock production systems to meet growing demand for meat. Furthermore, our team can build on existing infrastructure and laboratory capacity and years of interdisciplinary research collaboration in the livestock dense areas of Arusha and Kilimanjaro. Thus, there is both a need and the capacity to conduct this research. To achieve our aim, we will use an approach called modular process risk modelling (MPRM) to describe livestock meat pathways and hazards in these pathways. In the initial step, each stage of meat production from farm to retail is described by social and veterinary scientists. Local scale commercial production will be compared with wider markets to identify hazards that may emerge as meat production, processing and distribution is scaled up. Once the meat supply chain is charted, microbiologic techniques are used to establish the presence and concentration of non-typhoidal Salmonella and Campylobacter at each step in chain. By studying the genetic fingerprint of the bacteria, it is possible to track flow of bacteria from pre- to post-harvest. Comparison of DNA fingerprints of livestock and food isolates with those from bacterial isolates obtained from people with diarrhoea or other diseases will give an indication of the role of meat in human illness. Whilst mapping emerging livestock meat pathways and their associated hazards, we will conduct a formal review of current food safety policies and regulations in Tanzania and assess how they are implemented. Knowledge of the strengths and weaknesses of existing policies, combined with opportunities and threats identified through analysis of the meat value chain and hazards in the livestock meat pathway will enable scientists and policy makers to develop new food safety policies. Potential applications and benefits: Through its combination of social, biological and quantitative sciences and collaboration with policy makers, this project will contribute to improved food safety policy and reduction in food-borne exposure of people to non-typhoidal Salmonella and Campylobacter. This will provide economic and health benefits to producer and consumer communities in Tanzania. In addition, improved product safety may help farmers to access new retail markets. Finally, the approach developed in this project can serve as a model for other diseases and countries where changes in livestock production systems may affect the availability and safety of our food.