Al-Shorbaji Farah, Roche Benjamin, Britton Robert, Andreou Demetra, Gozlan Rodolphe
Bournemouth University, Faculty of Science and Technology, Dorset, UK.
Unit for Mathematical and Computer Modelling of Complex Systems, Institute of Research for Development, Montpellier, France.
J Anim Ecol. 2017 Sep;86(5):1147-1158. doi: 10.1111/1365-2656.12722. Epub 2017 Jul 31.
Outbreaks of generalist pathogens are influenced by host community structure, including population density and species diversity. Within host communities predation can influence pathogen transmission rates, prevalence and impacts. However, the influence of predation on community resilience to outbreaks of generalist pathogens is not fully understood. The role of predation on host community resilience to disease was assessed using an epidemiological multi-host susceptible-exposed-infectious-recovered model. Sphaerothecum destruens, an emerging fungal-like generalist pathogen, was used as a model pathogen. Six cyprinid and salmonid fishes, including an asymptomatic carrier, were selected as model hosts that are known to be impacted by S. destruens, and they were used within a model host community. Pathogen release into the host community was via introduction of the asymptomatic carrier. Mortality from infection, pathogen incubation rate, and host recovery rate were set to a range of evidence-based values in each species and were varied in secondary consumers to predict top-down effects of infection on the resilience of a host community. Predation pressure within the fish community was varied to test its effects on infection prevalence and host survival in the community. Model predictions suggested that predation of the asymptomatic hosts by fishes in the host community was insufficient to eliminate S. destruens. Sphaerothecum destruens persisted in the community due to its rapid transmission from the asymptomatic host to susceptible host fishes. Following transmission, pathogen prevalence in the community was driven by transmission within and between susceptible host fishes, indicating low host community resilience. However, introducing low densities of a highly specific piscivorous fish into the community to pre-date asymptomatic hosts could limit pathogen prevalence in the host community, thus increasing resilience. The model predictions indicate that whilst resilience to this generalist pathogen in the host community was low, this could be increased using management interventions. The results suggest that this model has high utility for predicting community resilience to disease and thus can be applied to other generalist parasites to determine risks of disease emergence.
泛病原体的爆发受到宿主群落结构的影响，包括种群密度和物种多样性。在宿主群落中，捕食行为会影响病原体的传播速率、流行程度和影响。然而，捕食行为对群落抵御泛病原体爆发的恢复力的影响尚未完全明确。利用一个流行病学多宿主易感-暴露-感染-恢复模型评估了捕食行为在宿主群落对疾病恢复力方面的作用。毁灭球囊菌是一种新出现的类似真菌的泛病原体，被用作模型病原体。选取了6种鲤科和鲑科鱼类，包括1种无症状携带者，作为已知受毁灭球囊菌影响的模型宿主，并将它们置于一个模型宿主群落中。通过引入无症状携带者将病原体释放到宿主群落中。在每个物种中，将感染死亡率、病原体潜伏期和宿主恢复率设定为一系列基于证据的值，并在二级消费者中进行变化，以预测感染对宿主群落恢复力的自上而下的影响。改变鱼类群落中的捕食压力，以测试其对群落中感染流行程度和宿主存活的影响。模型预测表明，宿主群落中的鱼类对无症状宿主的捕食不足以消除毁灭球囊菌。由于毁灭球囊菌能从无症状宿主快速传播到易感宿主鱼类，它在群落中持续存在。传播之后，群落中的病原体流行程度由易感宿主鱼类内部和之间的传播驱动，这表明宿主群落的恢复力较低。然而，向群落中引入低密度的高度特异性食鱼性鱼类来捕食无症状宿主，可以限制宿主群落中的病原体流行程度，从而提高恢复力。模型预测表明，虽然宿主群落对这种泛病原体的恢复力较低，但可以通过管理干预措施来提高。结果表明，该模型在预测群落对疾病恢复力方面具有很高的实用性，因此可应用于其他泛寄生虫，以确定疾病出现的风险。
