Optimal control strategies for rodent-borne zoonoses in Brazilian slum settlements

世界上10亿人口生活在贫民窟，占世界最贫穷国家城市人口的78%。居民因各种疾病而承受更大的负担。这些健康问题中有许多涉及人畜共患病--在野生动物或家养的“水库”宿主中传播的传染病，可以传播给人类，在那里它们可能导致严重的疾病或死亡。最近在人类身上出现的大多数传染病都是人畜共患病(例如艾滋病毒/艾滋病、埃博拉病毒)。大多数在野生动物中自然循环，通常是啮齿动物水库。因此，在城市贫民窟，特别是在贫穷国家，学会控制从啮齿动物蓄水池向人类传播感染是一项必须应对的挑战。钩端螺旋体病可能是传播最广泛的人畜共患病。宿主感染细菌钩端螺旋体，这种细菌感染宿主的肾脏，并随尿液排出。这是人类的最终感染源，尽管主要传播方式是接触受污染的水或土壤。钩端螺旋体病是人类的一种全身性疾病。表现从相对轻微到严重的危及生命的形式不等，其病例死亡率可能为50%。它的负担主要落在世界上最贫穷的人身上，他们传统上是以农村为基础的自给自足的农民，但最近从农村转移到城市。我们的研究将侧重于钩端螺旋体病，这本身就很重要，但该项目与贫民窟中的其他人畜共患病直接相关，并更广泛地与这些社区的健康相关。这项工作将在巴西萨尔瓦多的城市贫民窟进行。巴西每年在城市流行期间报告的钩端螺旋体病病例超过12000例，其中约12%是致命的。现实地说，城市贫困贫民窟中的钩端螺旋体病和类似疾病的威胁不会通过技术或复杂的措施来对抗。相反，全球卫生优先事项，也是我们项目的总体目标，是开发使在当地工作的机构能够最大限度地减少这些感染源构成的威胁的方法，使用可以有效、廉价且不需要复杂基础设施的方法。为此，我们将确定各种管理做法的后果(控制老鼠或环境)，以便找到最佳的干预措施，以最具成本效益的方式减少老鼠总种群数量，从而减少钩端螺旋体的数量和对人类的风险。我们可以说处于一个独特的位置来做这件事。我们拥有一支非常广泛的多学科团队，从医务人员到社会科学家，结合了来自英国、巴西和美国的专业知识，我们与当地公共卫生机构有着密切的联系。因此，通过我们的项目，我们将确定由当地机构指导并与当地机构合作的一系列控制战略的有效性(由一系列指标证明)。我们研究的总体结构将是对萨尔瓦多全市不同贫民窟目前采用的卫生控制措施的范围进行比较。经过在当地的协商，我们确定了至少在过去12个月中已经运作的三个类别，这些类别为我们提供了足够的场地来支持统计上有效的比较。将在每个地点收集以下数据：(I)老鼠数量；(Ii)携带钩端螺旋体和其他关键病原体的老鼠种群的比例；(Iii)环境中致病钩端螺旋体的浓度；(Iv)感染钩端螺旋体和这些其他关键病原体的人口比例；(V)过去20年来报告的人类钩端螺旋体病严重病例；以及(Vi)当地居民对卫生控制方法的态度，特别是对疾病风险的影响。

One billion of the world's population lives in slum settlements, comprising 78% of the urban populations from the world's poorest countries. Residents suffer an increased burden of a wide range of diseases. Many of these health problems involve zoonotic disease - infections circulating in wildlife or domesticated 'reservoir' hosts that can be transmitted to humans, where they can cause serious illness or mortality. Most of the infectious diseases that have emerged in humans recently are zoonotic (e.g. HIV-AIDS, Ebola). Most circulate naturally in wildlife, often rodent reservoirs. Hence, learning to control the spread of infection from rodent reservoirs to humans in urban slums, particularly in poor countries, is a challenge that must be addressed. Leptospirosis is perhaps the most widespread zoonotic disease. Hosts are infected with bacteria, leptospires, which infect the kidneys of reservoir hosts and are shed with the urine. This is the ultimate source of infection for humans, though the main mode of transmission is contact with contaminated water or soil. Leptospirosis is a systemic disease in humans. Manifestations range from relatively mild to severe life-threatening forms for which case fatality may be >50%. Its burden falls mainly on the world's poorest people, traditionally rural-based subsistence farmers, but recently shifting from a rural to an urban setting. Our study will focus on leptospirosis, which is important in its own right, but the project is directly relevant to other zoonoses in slum settings, and to the health of these communities more generally. The work will be carried out in the urban slums (favelas) of the city of Salvador, Brazil. More than 12,000 cases of leptospirosis are reported in Brazil during urban epidemics each year of which around 12% are fatal. Realistically, the threat from leptospirosis and similar diseases in impoverished urban slums will not be countered by technological or sophisticated measures. Rather, a global health priority, and an overarching aim of our program, is to develop the means of enabling agencies working locally to minimise the threat that these reservoirs of infection pose, using methodologies that can be applied effectively, cheaply, and without the need for a sophisticated infrastructure. To this end, we will determine the consequences of various management practices (controlling either rats or the environment) so that optimal interventions can be identified that reduce total rat population size, and hence the quantity of shed leptospires and the risk to humans, in the most cost-effective way. We are in an arguably unique position to do this. We have a very broad multi-disciplinary team from medics to social scientists, combining expertise from the UK, Brazil and the USA, and we have strong links to local public health agencies. Hence, through our project, we will determine the efficacy (evidenced by a range of metrics) of a range of control strategies, guided by, and in collaboration with, local agencies. The overall structure of our study will be a comparison of the range of sanitation-control measures currently being employed in different favelas across the municipality of Salvador. Following consultations locally, we have identified three categories that have been operational for at least the last twelve months, and that provide us with sufficient sites to support statistically valid comparisons. At each site, the following data will be collected: (i) rat abundance; (ii) the proportion of the rat populations carrying leptospires and other key pathogens (iii) concentrations of pathogenic leptospires in the environment; (iv) the proportion of the human population that have been infected with leptospires and these other key pathogens; (v) severe cases of leptospirosis reported in humans over the last 20 years; and (vi) attitudes of local residents to methods of sanitation control, especially in relation to effects on disease risk.