Epidemiological situation of yaws in the Americas: A systematic review in the context of a regional elimination goal

Background
Yaws is targeted for eradication by 2020 in the WHA66.12 resolution of the World Health Assembly. The objective of this study was to describe the occurrence of yaws in the Americas and to contribute to the compilation of evidence based on published data to undertake the certification of yaws eradication.
Methodology
A systematic review of the epidemiological situation of yaws in the Americas was performed by searching in MEDLINE, Embase, LILACS, SCOPUS, Web of Science, DARE and Cochrane Database of Systematic Reviews. Experts on the topic were consulted, and institutional WHO/PAHO library databases were reviewed.
Principal findings
Seventy-five full-text articles published between 1839 and 2012 met the inclusion criteria. Haiti and Jamaica were the two countries with the highest number of papers (14.7% and 12.0%, respectively). Three-quarters of the studies were conducted before 1970. Thirty-three countries reported yaws case count or prevalence data. The largest foci in the history were described in Brazil and Haiti. The most recent cases reported were recorded in eight countries: Suriname, Guyana, Colombia, Haiti, Martinique, Dominica, Trinidad and Tobago, and Brazil. Gaps in information and heterogeneity were detected in the methodologies used and outcome reporting, making cross-national and chronological comparisons difficult.
Conclusions
The lack of recent yaws publications may reflect, in the best-case scenario, the interruption of yaws transmission. It should be possible to reach the eradication goal in the region of the Americas, but it is necessary to collect more information. We suggest updating the epidemiological status of yaws, especially in two countries that need to assess ongoing transmission. Twenty-four countries need to demonstrate the interruption of transmission and declare its status of yaws endemicity, and sixteen countries should declare if they are yaws-free. It is necessary to formally verify the achievement of this goal in Ecuador.

背景
雅司病（yaws）被纳入世界卫生大会（World Health Assembly）WHA66.12号决议，计划于2020年前实现根除。本研究旨在描述美洲地区雅司病的流行情况，并基于已发表数据汇编证据，为雅司病根除认证工作提供支持。

研究方法
本研究对美洲地区雅司病的流行病学现状开展系统综述，检索了MEDLINE、Embase、LILACS、SCOPUS、Web of Science、DARE以及科克伦系统综述数据库（Cochrane Database of Systematic Reviews）。本研究咨询了该领域专家，并对世界卫生组织/泛美卫生组织（World Health Organization/ Pan American Health Organization, WHO/PAHO）的机构图书馆数据库进行了梳理。

主要研究结果
1839年至2012年间发表的75篇全文文献符合纳入标准。其中，海地和牙买加的相关文献占比最高，分别为14.7%和12.0%。四分之三的研究开展于1970年之前。共有33个国家报告了雅司病的病例数或流行率数据。历史上规模最大的雅司病疫源地见于巴西与海地。目前有公开报告的最新雅司病病例来自8个国家：苏里南、圭亚那、哥伦比亚、海地、马提尼克、多米尼克、特立尼达和多巴哥以及巴西。研究发现，现有文献在研究方法与结果报告方面存在信息缺口与异质性问题，这使得跨国及跨时间比较难以开展。

结论
从最优情况来看，近期缺乏雅司病相关文献或许反映出雅司病传播已被阻断。美洲地区有望实现雅司病根除目标，但仍需收集更多相关数据。本研究建议更新雅司病的流行病学现状，尤其是需要对持续传播情况进行评估的两个国家。共有24个国家需要证明其已阻断雅司病传播并宣布本国的雅司病流行状态，另有16个国家需声明本国是否已无雅司病病例。厄瓜多尔需正式验证该根除目标的达成情况。