Targeted screening for Taenia solium tapeworms

描述(申请人提供)：神经囊虫病(NCC)是最常见的中枢神经系统寄生虫感染，也是发展中国家获得性癫痫的主要原因。当某人摄入猪带绦虫携带者的粪便中通过的猪带绦虫卵时，就会发生这种情况。卵子发育成幼虫，然后在全身形成包囊；在发展中国家，脑包囊导致了30%的癫痫发作。在拉丁美洲，所有年龄和社会经济阶层的40多万人都有NCC的症状。人类绦虫携带者的迁徙、传播的持续条件以及绦虫的巨大繁殖能力限制了控制努力的可持续性。我们的长期目标有两个：1)制定有效、负担得起和可持续的战略，在流行地区控制沙门氏菌；2)提高秘鲁农村地区围绕神经疾病的人口研究能力。在这笔R21拨款中，我们首先对作为控制策略的定向筛查的可行性进行研究，并利用现有财团的资源将研究和公共卫生培训、现场经验和指导扩展到秘鲁普诺的两名医生。现场数据显示，受感染的猪在绦虫携带者周围的空间聚集。由于饲养供食用的猪的寿命很短，这表明受感染的猪可能标志着附近存在绦虫携带者。我们的具体目标包括：1)在受感染的猪周围的家庭群中实施和评估人类猪带绦虫携带者的有针对性的筛查，以及2)在有针对性的筛查的背景下确定对绦虫携带者最有效的筛查工具。我们提出了一个有两个研究臂的干预队列。干预组中的社区使用所有可用的筛查工具(通过虫段的历史、O&P、辅抗原ELISA、EITB和PCR)，对受感染猪周围的家庭群中的绦虫携带者进行持续的定向筛查。控制组中的社区接受关于沙门氏菌生命周期和如何预防感染的教育。我们每5个月对两组进行一次猪血清调查，用猪血清阳性率来衡量总体传播情况，并在研究结束时进行大规模绦虫筛查和治疗。我们的主要假设是，正在进行的针对绦虫携带者的有针对性的筛查和治疗将减少流行地区的猪弓形虫感染的传播，这是通过一系列猪血清阳性率来衡量的。我们的第二个假设是，与流行地区的普遍筛查相比，在囊虫病猪周围进行有针对性的筛查将增加对猪囊尾绦虫的检测。我们使用所有筛查结果的潜在类别分析来估计家庭集群中的感染流行率。最后，我们使用决策分析来确定目标筛选的最有效的筛选工具，考虑到测试性能、成本和相对可获得性。我们的研究结果将指导使用这项研究中确定的最有希望的方法进行后续大规模防治干预的设计。 与公共卫生相关：囊虫病是许多发展中国家新出现的公共卫生问题，是可预防癫痫的主要原因。这项提案审查了对猪肉绦虫携带者进行有针对性的筛查，作为一种潜在有效、负担得起和可持续的控制策略。

DESCRIPTION (provided by applicant): Neurocysticercosis (NCC) is the most common parasitic infection of the central nervous system, and the leading cause of acquired epilepsy in the developing world. It occurs when someone ingests Taenia solium eggs passed in the feces of a pork tapeworm carrier. The eggs grow into larvae which then form cysts throughout the body; cysts in the brain are responsible for 30% of seizures in the developing world. In Latin America, over 400,000 people of all ages and socioeconomic classes have symptomatic NCC. Sustainability of control efforts is limited by migration of human tapeworm carriers, persistent conditions for transmission and the enormous reproductive capacity of tapeworms. Our long-term goals are two-fold; 1) to develop an effective, affordable and sustainable strategy for T. solium control in endemic areas, and 2) to increase population-based research capacity around neurologic disorders in rural regions of Peru. In this R21 grant, we begin with a feasibility study of targeted screening as a control strategy, and by leveraging the resources of an existing consortium to extend research and MPH training, field experience, and mentorship to two physicians in Puno, Peru. Field data show spatial clustering of infected pigs around tapeworm carriers. With the short lifespan of pigs raised for consumption, this suggests that infected pigs may mark the presence of a nearby tapeworm carrier. Our specific aims include: 1) To implement and assess targeted screening for human T. solium tapeworm carriers in household clusters surrounding infected pigs, and 2) To identify the most effective screening tools for tapeworm carriers in the context of targeted screening. We propose an intervention cohort with two study arms. Communities in the intervention group receive ongoing targeted screening for tapeworm carriers in household clusters around infected pigs, using all available screening tools (history of passing worm segments, O&P, coproantigen ELISA, EITB, and PCR). Communities in the control group receive education about the T. solium lifecycle and how to prevent infection. We conduct pig serosurveys in both groups every 5 months, using pig seroprevalence to measure overall transmission, and provide mass tapeworm screening and treatment at study end. Our primary hypothesis is that ongoing targeted screening and treatment of tapeworm carriers will decrease transmission of T. solium infection in an endemic area, measured by serial pig seroprevalence. Our secondary hypothesis is that targeted screening around pigs with cysticercosis will increase detection of T. solium tapeworms compared to generalized screening in endemic areas. We estimate prevalence of infection among household clusters using latent-class analysis of all screening results. Finally, we use decision-making analysis to determine the most effective screening tool for targeted screening, taking into consideration test performance, cost, and relative accessibility. Our results will guide design of a subsequent large-scale T. solium control intervention using the most promising methods identified in this study. PUBLIC HEALTH RELEVANCE: Cysticercosis is an emerging public health problem in much of the developing world, where it is the leading cause of preventable epilepsy. This proposal examines targeted screening for pork tapeworm carriers as a potentially effective, affordable and sustainable control strategy.