Towards the strategic control of endemic foot-and-mouth disease in Africa: new techniques for a neglected problem

口蹄疫是偶蹄动物的一种非常严重的病毒性疾病，它对动物的健康、生产力和随之而来的贸易限制造成巨大的经济损失。虽然人们对口蹄疫病毒(口蹄疫病毒)的生物学相当了解，因为它发生在发达国家的暴发环境中，但这种理解还没有应用于世界上病毒长期存在的地区。这尤其令人遗憾，因为口蹄疫对小农户有严重影响，而且以前的研究将口蹄疫列为与贫困有关的最重要的牲畜疾病之一。坦桑尼亚拥有非洲第三大家畜种群，牲畜对生活在坦桑尼亚农村的数百万人的营养和经济福利至关重要。农村社区直接依赖牲畜获得食物、牛奶、在作物生产中使用动物以及通过当地销售筹集资金。口蹄疫会导致动物体重减轻、产奶量减少、行动不便和经济价值下降，因此对直接依赖牲畜健康的社区来说，对口蹄疫的控制尤为重要。口蹄疫病毒经常感染水牛和其他野生有蹄类动物，野生动物经常被怀疑是导致家畜疾病的病毒的直接或最终来源。这导致了野生动物的管理和家畜之间的冲突，野生动物本身在坦桑尼亚等国是非常重要的财政资源，人们呼吁修建类似于南部非洲的围栏，以减少家畜和野生动物之间的接触。迫切需要了解野生动物作为家畜口蹄疫来源的重要性，并找到更环保的方法来防止病毒从野生动物保护区传播出去。口蹄疫可以通过接种疫苗来控制，但疫苗并不完美，只提供了针对疾病症状的短暂保护，而不是感染本身，并且只针对有限范围的病毒基因类型提供保护。为了有效地使用疫苗接种，关键是要知道可能导致动物感染的病毒的基因类型，以便能够选择最好的疫苗。不幸的是，尽管很容易获得这种知识，但从被认为存在该病毒的非洲非常大的地区几乎完全缺乏这种知识。该项目旨在对坦桑尼亚10个不同地区的牲畜和野生动物进行大规模口蹄疫调查。将从家畜和野生动物中采集血液样本，并进行检测，以寻找以前感染口蹄疫的证据，这将提供目前最重要的病毒类型的大致情况。在病毒被真正分离的地方，我们将对部分基因组进行测序，以获得关于病毒类型的更详细的信息。我们还将重点关注坦桑尼亚北部的一个地区，开展更详细的长期研究，定期从牛群中采集血液样本，并在口蹄疫爆发期间收集病毒并对其进行测序。使用这些数据，我们将能够确定导致感染的病毒来自哪里(是该地区的野生动物或其他家养动物，还是它在感染的畜群中进化？)。我们还将研究长期感染口蹄疫病毒的动物的作用，确定与感染口蹄疫病毒有关的其他养殖做法，并研究感染一种毒株所引起的免疫保护能在多大程度上保护动物免受其他毒株的感染。

Foot-and-mouth disease (FMD) is a very serious viral disease of cloven-hooved animals, which causes immense economic losses through its impacts on animal health, productivity, and consequent trading constraints. While the biology of foot-and-mouth disease virus (FMDV) is quite well-understood as it occurs in outbreak settings in developed countries, this understanding has not been applied to regions of the world where the virus is permanently present. This is particularly unfortunate, since FMD has serious impacts for small-farmers, and previous studies rank FMD as one of the most important livestock diseases associated with poverty. Tanzania has the third largest population of domestic livestock in Africa, and livestock are critical for the nutrition and economic welfare of the millions of people who live in rural Tanzania. Rural communities depend directly on livestock for food, milk, use of animals in crop production, and in raising money through local sales. FMD causes animals to lose weight, reduce milk production, become immobile, and reduce in financial value, and therefore its control is particularly important for communities who depend directly on the well-being of their livestock. FMDV is often found to infect buffalo and other wild ungulates, and wildlife are often suspected to be either the direct of ultimate source of viruses causing disease in domestic livestock. This has led to conflict between the management of wildlife, which is itself a hugely important financial resource in countries like Tanzania, and domestic livestock, with calls for the construction of fences similar to those constructed in southern Africa that serve to reduce contact between domestic livestock and wildlife. There is an urgent need to understand how important wildlife is as a source of FMD for domestic livestock, and to find more environmentally-friendly ways of preventing the virus from moving out from wildlife sanctuaries. FMD can be controlled through the use of vaccination, but the vaccines are not perfect, providing only short-lived protection from the symptoms of the disease rather than infection itself, and protecting against only a limited range of genetic types of the virus. In order to use vaccination effectively, it is critical to know the genetic types of the virus that are likely to cause infection in animals, so that the best vaccines can be chosen. Unfortunately, although quite easily obtained, this knowledge is almost completely lacking from very large areas of Africa in which the virus is thought to be present. This project aims to conduct a large-scale survey of FMD in livestock and wildlife in 10 different areas across Tanzania. Blood samples will be collected from domestic livestock and wildlife and tested for evidence of previous infection by FMD and this will provide a crude picture of the most important types of virus that are present. Where virus is actually isolated we will sequence parts of the genome to obtain much more detailed information on the virus types. We will also focus on one area in northern Tanzania to carry out a more detailed longer-term study, collecting blood samples from herds at regular time intervals and collecting viruses during FMD outbreaks and sequencing them. Using these data, we will be able to determine where virus that causes infections comes from (is it wildlife or other domestic animals in the region, or does it evolve within the herds that its infecting?). We will also study the role of animals that have long-term infections of FMDV, identify other farming practices that are associated with infection by FMDV, and study just how much immune protection caused by infection with one strain can protect animals from infection with other strains.