Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA 16802, USA.
Biol Lett. 2012 Jun 23;8(3):465-8. doi: 10.1098/rsbl.2011.1075. Epub 2011 Dec 21.
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.
寄生虫和病原体在媒介中的发育速度通常随温度升高而加快。因此，在较温暖的条件下，传播强度通常被认为更高。然而，发育只是寄生虫/病原体生活史的一个组成部分，很少有研究探索有助于传播强度的其他特征的温度敏感性。在这里，我们使用一种啮齿动物疟疾表明，即使寄生虫的发育速度增加，媒介能力（感染性蚊子的最大比例，这隐含地包括在潜伏期内寄生虫的生存）在较高温度下会下降。我们还表明，寄生虫潜伏期的标准衡量标准（即从受感染的血液餐中，一个群体中第一只感染蚊子出现的时间）是不完整的，因为寄生虫的发育遵循累积分布，而累积分布本身随温度而变化。在一个简单的模型中包含这些影响会极大地改变对传播强度的估计，并降低传播的最佳温度。这些结果强调了需要了解环境温度对多种宿主疾病生活史特征的相互作用影响，并挑战了许多当前忽视这种复杂性的疾病模型的假设。
