Targeted screening for Taenia solium tapeworms

描述（由申请人提供）：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。当某人摄入了猪肉绦虫携带者粪便中传播的猪带绦虫卵时，就会发生这种情况。卵长成幼虫，然后在全身形成囊肿；在发展中国家，30%的癫痫发作是由脑部囊肿引起的。在拉丁美洲，所有年龄和社会经济阶层中有40多万人患有有症状的非传染性细胞癌。控制工作的可持续性受到人类绦虫携带者迁移、持续传播条件和绦虫巨大繁殖能力的限制。我们的长期目标是双重的；1)在流行地区制定有效、负担得起和可持续的血吸虫控制战略；2)提高秘鲁农村地区以人群为基础的神经系统疾病研究能力。在这项R21资助中，我们首先对靶向筛查作为一种控制策略的可行性进行研究，并利用现有联盟的资源，将研究和公共卫生硕士培训、现场经验和对秘鲁普诺的两名医生的指导扩大。现场数据显示受感染的猪在空间上聚集在绦虫携带者周围。由于食用猪的寿命较短，这表明受感染的猪可能表明附近存在绦虫携带者。我们的具体目标包括：1)实施和评估在感染猪周围的家庭聚集性人类绦虫携带者的靶向筛查；2)在靶向筛查的背景下，确定最有效的绦虫携带者筛查工具。我们建议采用两个研究组的干预队列。干预组社区使用所有可用的筛查工具（虫段传播史、O&P、粪原抗原ELISA、EITB和PCR），对感染猪周围家庭聚集的绦虫携带者进行持续的靶向筛查。对照组社区接受血吸虫生命周期及如何预防感染的教育。我们每5个月对两组猪进行一次血清调查，利用猪血清阳性率来衡量总体传播情况，并在研究结束时提供大规模绦虫筛查和治疗。我们的主要假设是，通过连续猪血清流行率测量，对绦虫携带者进行有针对性的筛查和治疗将减少绦虫感染在流行地区的传播。我们的第二个假设是，与流行地区的普遍筛查相比，在患有囊虫病的猪周围进行针对性筛查将增加猪绦虫的检出率。我们使用所有筛查结果的潜在类分析来估计家庭聚集性感染的流行程度。最后，考虑到测试性能、成本和相对可及性，我们使用决策分析来确定最有效的靶向筛选工具。我们的研究结果将指导使用本研究中确定的最有希望的方法设计后续的大规模茄蚜控制干预措施。

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.