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研究发现气温升高不一定增强疟疾传播能力

2011/12/24 来源:健康报
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在全球变暖的大背景下,许多人担心疟疾的传播能力会随温度升高而增强。但一项最新研究显示未必如此,气温升高反而有可能削弱疟疾的传播能力。

在全球变暖的大背景下,许多人担心疟疾的传播能力会随温度升高而增强。但一项最新研究显示未必如此,气温升高反而有可能削弱疟疾的传播能力。

英国皇家学会主办的《生物学通讯》杂志21日刊登报告说,美国宾夕法尼亚州立大学的研究人员在20、22、24和26摄氏度等不同温度条件下,培养了感染疟原虫的蚊子。结果显示,温度较高的时候,虽然疟原虫的生长发育速度加快,但最终能形成有传染力的孢子比例却反而下降。

孢子是疟原虫在蚊子体内发育的最终形式,发育到孢子形态的疟原虫会进入蚊子的唾液腺,在蚊子叮咬人类时进入人体传播疟疾。此前多项研究已经发现,气温升高会使疟原虫在蚊子体内的生长发育速度加快,这是许多人认为疟疾传播能力会增强的原因,但过去的研究没有涉及孢子的状况。

从本次研究的数据来看,虽然疟原虫的发育速度在26摄氏度时最快,但最终形成孢子的比例却是在22摄氏度时最高,综合分析疟疾传播风险应该是在24摄氏度时最大。不过研究人员还表示,要推断真实世界中的疟疾传播风险,还需要考虑温度变化对蚊子叮咬人类习性的影响等因素。

研究人员指出,在关于全球变暖的讨论中经常有预测认为疟疾传播风险会随温度升高而增大,但预测没有全面考虑气温变化对疟原虫的多方面影响,这还需要更细致的研究。

 

Warmer temperatures reduce the vectorial capacity of malaria mosquitoes

Krijn P. Paaijmans, Simon Blanford, Brian H. K. Chan and Matthew B. Thomas 

The development rate of parasites and pathogens within vectors typically increases with temperature. Accordingly, transmission intensity is generally assumed to be higher under warmer conditions. However, development is only one component of parasite/pathogen life history and there has been little research exploring the temperature sensitivity of other traits that contribute to transmission intensity. Here, using a rodent malaria, we show that vector competence (the maximum proportion of infectious mosquitoes, which implicitly includes parasite survival across the incubation period) tails off at higher temperatures, even though parasite development rate increases. We also show that the standard measure of the parasite incubation period (i.e. time until the first mosquitoes within a cohort become infectious following an infected blood-meal) is incomplete because parasite development follows a cumulative distribution, which itself varies with temperature. Including these effects in a simple model dramatically alters estimates of transmission intensity and reduces the optimum temperature for transmission. These results highlight the need to understand the interactive effects of environmental temperature on multiple host-disease life-history traits and challenge the assumptions of many current disease models that ignore this complexity.

文献链接:http://rsbl.royalsocietypublishing.org/content/early/2011/12/15/rsbl.2011.1075.abstract?sid=fc800ca6-9f7d-4cef-884a-803dc497103a

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