Data from: Costs of crowding for the transmission potential in malaria parasites

The utility of using evolutionary and ecological frameworks to understand the dynamics of infectious diseases is gaining increasing recognition. However, integrating evolutionary ecology and infectious disease epidemiology is challenging because within-host dynamics can have counterintuitive consequences for between-host transmission, especially for vector-borne parasites. A major obstacle to linking within- and between-host processes is that the drivers of the relationships between the density, virulence, and fitness of parasites are poorly understood. By experimentally manipulating the intensity of rodent malaria (Plasmodium berghei) infections in Anopheles stephensi mosquitoes under different environmental conditions, we show that parasites experience substantial density-dependent fitness costs because crowding reduces both parasite proliferation and vector survival. We then use our data to predict how interactions between parasite density and vector environmental conditions shape within-vector processes and onward disease transmission. Our model predicts that density-dependent processes can have substantial and unexpected effects on the transmission potential of vector-borne disease, which should be considered in the development and evaluation of transmission-blocking interventions.利用进化与生态学框架解析传染病动态的研究价值正获得日益广泛的认可。然而，整合进化生态学与传染病流行病学的研究仍面临诸多挑战——这是由于宿主体内的动态变化会对宿主间传播产生反直觉的影响，对于媒介传播寄生虫而言这一问题尤为突出。制约宿主体内与宿主间过程关联的核心障碍之一，是寄生虫密度、毒力与适合度之间关系的驱动机制仍未得到充分阐明。本研究通过在不同环境条件下，对斯氏按蚊（Anopheles stephensi）体内的啮齿类疟疾致病原——伯氏疟原虫（Plasmodium berghei）感染强度开展实验操控，结果证实寄生虫会承受显著的密度依赖性适合度代价：种群拥挤会同时抑制寄生虫增殖并降低媒介昆虫的存活率。随后，研究团队依托实验数据，预测了寄生虫密度与媒介环境条件之间的交互作用如何塑造媒介体内的寄生虫过程以及后续的疾病传播。我们的模型预测结果显示，密度依赖性过程会对媒介传播疾病的传播潜能产生显著且超出预期的影响，这一发现应当在阻断传播干预手段的开发与评估中得到充分考量。