Schistosomiasis Prevalence and Intensity of Infection in Latin America and the Caribbean Countries, 1942-2014: A Systematic Review in the Context of a Regional Elimination Goal

Background
In 2012 the World Health Assembly adopted resolution WHA65.21 on elimination of schistosomiasis, calling for increased investment in schistosomiasis control and support for countries to initiate elimination programs. This study aims to analyze prevalence and intensity of Schistosoma mansoni infection in children in Latin America and the Caribbean countries and territories (LAC), at the second administrative level or lower.
Methodology
A systematic review of schistosomiasis prevalence and intensity of infection was conducted by searching at PubMed, LILACS and EMBASE. Experts on the topic were informally consulted and institutional web pages were reviewed (PAHO/WHO, Ministries of Health). Only SCH infection among children was registered because it can be a ‘proxi-indicator’ of recent transmission by the time the study is conducted.
Principal Findings
One hundred thirty two full-text articles met the inclusion criteria and provided 1,242 prevalence and 199 intensity of infection data points. Most of them were from Brazil (69.7%). Only Brazil published studies after 2001, showing several 'hot spots' with high prevalence. Brazil, Venezuela, Suriname and Saint Lucia need to update the epidemiological status of schistosomiasis to re-design their national programs and target the elimination of Schistosoma mansoni transmission by 2020. In Antigua and Barbuda, Dominican Republic, Guadeloupe, Martinique, Montserrat and Puerto Rico schistosomiasis transmission may be interrupted. However the compilation of an elimination dossier and follow-up surveys, per WHO recommendations, are needed to verify that status. Hence, the burden of subtle SCH chronic infection may be still present and even high in countries that may have eliminated transmission. Heterogeneity in the methodologies used for monitoring and evaluating the progress of the schistosomiasis programs was found, making cross-national and chronological comparisons difficult.
Conclusions
There is a need for updating the schistosomiasis status in the historically endemic countries and territories in LAC to address the required public health interventions for control and elimination programs or to verify the elimination of transmission of Schistosoma mansoni. Improved reporting and standardization of the monitoring and evaluation methodologies used are recommended, while using available WHO guidelines. Meeting a regional elimination goal will require additional and improved epidemiological data by age group and sex.

背景
2012年世界卫生大会通过WHA65.21号关于消除血吸虫病的决议，呼吁加大血吸虫病防控投入，并支持各国启动消除项目。本研究旨在分析拉丁美洲及加勒比地区（Latin America and the Caribbean, LAC）国家和辖区内儿童的曼氏血吸虫（Schistosoma mansoni）感染率与感染强度，分析层级为二级行政区及更低级别。

研究方法
本研究针对血吸虫病感染率与感染强度开展系统综述，通过检索PubMed、LILACS及EMBASE数据库完成文献检索，同时非正式咨询本领域专家，并梳理了泛美卫生组织/世界卫生组织（PAHO/WHO）、各国卫生部等机构的官方网页。本研究仅纳入儿童血吸虫感染相关数据，因其可作为研究实施阶段近期传播的替代指标。

主要研究结果
共有132篇全文文献符合纳入标准，共提供1242条感染率数据点与199条感染强度数据点。其中绝大多数数据来自巴西（占比69.7%），且仅巴西在2001年后发表了相关研究，其境内存在多处高感染率的“热点区域”。巴西、委内瑞拉、苏里南及圣卢西亚需更新血吸虫病流行病学现状，以重新制定国家防控方案，目标在2020年前消除曼氏血吸虫传播。安提瓜和巴布达、多米尼加共和国、瓜德罗普、马提尼克、蒙特塞拉特及波多黎各的血吸虫病传播或已中断，但根据世界卫生组织建议，仍需编制消除档案并开展后续随访调查，以验证这一状态。因此，在已宣称消除传播的国家中，仍可能存在隐匿的慢性血吸虫感染负担，甚至感染程度较高。本研究同时发现，各国血吸虫病防控项目的监测与评估方法存在异质性，这使得跨国及跨时间比较难以开展。

研究结论
拉丁美洲及加勒比地区既往血吸虫病流行国家和辖区需更新血吸虫病流行现状，以落实防控与消除项目所需的公共卫生干预措施，或验证曼氏血吸虫传播是否已被消除。研究建议在遵循世界卫生组织现有指南的基础上，进一步完善监测与评估方法的报告规范与标准化水平。要实现区域消除目标，还需按年龄组与性别细分，补充并优化现有的流行病学数据。