Host nutrition alters the variance in parasite transmission potential

The environmental conditions experienced by hosts are known to affect their mean parasite transmission potential. How different conditions may affect the variance of transmission potential has received less attention but is an important question for disease management, especially if specific ecological contexts are more likely to foster a few extremely infectious hosts. Using the obligate-killing bacterium Pasteuria ramosa and its crustacean host Daphnia magna, we analysed how host nutrition affected the variance of individual parasite loads, and therefore transmission potential. Under low food, individual parasite loads showed similar mean and variance, following a Poisson distribution. In contrast, among well-nourished hosts, parasite loads were right-skewed and over dispersed, following a negative binomial distribution. Abundant food may therefore yield individuals causing potentially more transmission than the population average. Measuring both the mean and variance of individual pa...

已知宿主所处的环境条件会影响其平均寄生虫传播潜能。然而，不同环境条件如何调控传播潜能的方差这一问题却未得到足够关注，但它却是疾病防控领域的关键议题——尤其是当特定生态环境更易催生少数传染性极强的宿主时。本研究以专性致死细菌锈质芽孢杆菌（Pasteuria ramosa）及其甲壳类宿主大型溞（Daphnia magna）为实验模型，分析了宿主营养状况对个体寄生虫载量方差的影响，进而明确其对传播潜能的作用。在食物匮乏条件下，个体寄生虫载量的均值与方差近似相等，符合泊松分布（Poisson distribution）。与之相对，营养充足的宿主群体中，寄生虫载量呈现右偏分布且存在过离散现象，符合负二项分布（negative binomial distribution）。由此可见，充足的食物供给可能会产生传播潜能高于种群平均水平的个体。对个体寄生虫载量的均值与方差进行测量