Where snails no longer fear to tread.
Where snails no longer fear to tread.
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蜗牛不再害怕踏足的地方。
DOI：
10.4269/ajtmh.2008.78.185
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
C. King
中科院分区：
文献类型：
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作者：
C. King
全球变暖及其随之而来的气候变化的现实似乎是无可争议的，即使各国政府继续就其原因和可能的补救措施争论不休。现在，对于《华尔街日报》的读者(即我们当中最熟悉“热带”感染的人)来说，预测气候变化将对疾病传播产生的影响似乎是谨慎的。特别值得关注的将是现在被归类为亚热带或温带的气候发生的变化。在这一期的《华尔街日报》上，周晓农等人利用先进的、参数化良好的空间分析技术，绘制了气候变化对中国血吸虫病传播的可能影响。尤其重要的是，在中国传播血吸虫病的钉螺具有耐寒能力，可以在冬季平均气温降至0摄氏度的地区生存。此外，钉螺的繁殖率与温度有关，感染钉螺的日本血吸虫孢子囊发育率也是如此。因此，可以使用温度值来预测哪里的钉螺种群会繁盛，哪里有可能传播日本血吸虫。基于不同环境温度下钉螺和血吸虫存活的实验室模型，假设与全球变暖相关的平均温度上升增加了钉螺栖息地的范围。同时，较长的季节平均气温(15.4℃)(寄生虫生长所需的最低温度)意味着寄生虫生长和传播所需的“累积度日”将逐渐在更多的地区发生。最终，随着全球变暖的进展，目前被认为是蜗牛和血吸虫栖息地边缘的更多地区预计将成为公认的传播区。利用空间建模技术，周和其他人仔细地将他们的蜗牛-寄生虫生存模型与环境数据融合在一起，提供了基于证据的地图，预测了2030年和2050年中国的日本血吸虫传播区。他们的气候预测是基于他们自己对中国全境193个气象站报告的温度的时间序列分析，结合这些空间参考数据的加权内插(克立格)，以提供传播风险的预测。作为一个经过验证的基线，他们准确地模拟了2000年适合传播的地区，并根据预期的区域变暖趋势预测了未来的栖息地扩展。克立格插值法特别适用于数据支持很强(即一致的多年和多地点记录)的项目。克里格法还为我们提供了关于其预测误差幅度的信息，表明哪里仍然需要更好的信息输入。周等人的研究预测，日本血吸虫的传播范围将广泛扩大，包括在中国内部向北和向西传播，到2050年估计增加784,000公里的受威胁领土。作者总结说，尽管中国在许多地区减少血吸虫病流行方面取得了巨大成功，但人类迁徙、土木工程对环境的改变，以及最终显著的气候变暖，很容易压倒他们目前控制血吸虫病的方法。这种有根有据的分析提出了一个重要的警告，无疑应该为规划未来的监测和控制提供一个有效的重点。
The reality of global warming and its consequent climate change seems indisputable, even if governments continue to argue about their causes and possible remedies. It would now seem prudent for Journal readers (i.e., those among us who are most familiar with the “tropical” infections) to anticipate the impact that climate change will have on disease transmission. Of special concern will be the changes that occur in climates now classified as sub-tropical or temperate. In this issue of the Journal, Xiao-Nong Zhou and others use advanced and well-parameterized spatial analytic techniques to map out the probable impact of climate change on schistosomiasis transmission in China. Of particular importance is that fact that Oncomelania hupensis, the snail that transmits schistosomiasis in China, is cold tolerant and can survive in areas experiencing mean temperatures down to 0°C during the winter months. In addition, snail reproduction rates are temperature dependent, as is the rate of Schistosoma japonicum sporocyst development in infected snails. As a result, it is possible to use temperature values to predict where snail populations will thrive and where S. japonicum transmission is possible. Based on laboratory models of snail and schistosome survival at different ambient temperatures, the increasing average temperatures associated with global warming are hypothesized to increase the ranges of O. hupensis habitat. At the same time, longer seasonal periods of mean temperatures > 15.4°C (the minimum temperature needed for parasite development) mean that the “accumulated degree-days” necessary for parasite development and transmission will occur in progressively more regions than before. Ultimately, as global warming progresses, more areas currently deemed as marginal for snail and schistosome habitat are expected to become recognized transmission zones. Using spatial modeling techniques, Zhou and others have carefully melded their snail–parasite survival models with environmental data to provide evidence-based maps projecting areas of S. japonicum transmission in China in 2030 and 2050. Their climate projections are based on their own time-series analysis of temperatures reported from 193 weather stations across China, combined with weighted interpolation (Kriging) of this spatially referenced data, to provide predictions of transmission risk. As a validated baseline, they accurately model areas suitable for transmission in 2000 and project habitat extensions in the future based on expected regional warming trends. The Kriging interpolation approach is particularly suitable in projects such as this where the data support is strong (i.e., consistent multi-year and multi-location recordings). Kriging also provides us information on the margin of error in its predictions, indicating where better information inputs are still needed. The study of Zhou and others predicts that the range of S. japonicum transmission will expand broadly, both northward and westward within China, adding an estimated 784,000 km of threatened territory by 2050. The authors conclude that despite China’s great successes in reducing schistosomiasis prevalence in many areas, a combination of human migration, civil engineering changes to the environment, and, finally, significant climate warming can easily overwhelm their current approaches to schistosomiasis control. This wellgrounded analysis raises a significant alarm and should no doubt provide a valid focus for planning future surveillance and control.