Department of Biology, University of Central Florida, Orlando, Florida, USA.
J Anim Ecol. 2023 Sep;92(9):1856-1868. doi: 10.1111/1365-2656.13977. Epub 2023 Jul 6.
Amphibians suffer from large-scale population declines globally, and emerging infectious diseases contribute heavily to these declines. Amphibian Perkinsea (Pr) is a worldwide anuran pathogen associated with mass mortality events, yet little is known about its epidemiological patterns, especially in comparison to the body of literature on amphibian chytridiomycosis and ranavirosis. Here, we establish Pr infection patterns in natural anuran populations and identify important covariates including climate, host attributes and co-infection with Ranavirus (Rv). We used quantitative (q)PCR to determine the presence and intensity of Pr and Rv across 1234 individuals sampled throughout central Florida in 2017-2019. We then implemented random forest ensemble learning models to predict infection with both pathogens based on physiological and environmental characteristics. Perkinsea infected 32% of all sampled anurans, and Pr prevalence was significantly elevated in Ranidae frogs, cooler months, metamorphosed individuals and frogs co-infected with Rv, while Pr intensity was significantly higher in ranid frogs and individuals collected dead. Ranavirus prevalence was 17% overall and was significantly higher in Ranidae frogs, metamorphosed individuals, locations with higher average temperatures, and individuals co-infected with Pr. Perkinsea prevalence was significantly higher than Rv prevalence across months, regions, life stages and species. Among locations, Pr prevalence was negatively associated with crayfish prevalence and positively associated with relative abundance of microhylids, but Rv prevalence did not associate with any tested co-variates. Co-infections were significantly more common than single infections for both pathogens, and we propose that Pr infections may propel Rv infections because seasonal Rv infection peaks followed Pr infection peaks and random forest models found Pr intensity was a leading factor explaining Rv infections. Our study elucidates epidemiological patterns of Pr in Florida and suggests that Pr may be under-recognized as a cause of anuran declines, especially in the context of pathogen co-infection.
两栖动物在全球范围内遭受着大规模的种群减少，而新出现的传染病是导致这些减少的主要原因之一。两栖动物 Perkinsea (Pr) 是一种全球性的无尾目病原体，与大规模死亡事件有关，但人们对其流行病学模式知之甚少，特别是与关于两栖动物壶菌病和 Ranavirosis 的文献相比。在这里，我们在自然无尾目种群中建立了 Pr 感染模式，并确定了重要的协变量，包括气候、宿主属性和与 Ranavirus (Rv) 的合并感染。我们使用定量 (q)PCR 来确定 2017-2019 年在佛罗里达州中部采样的 1234 个人中 Pr 和 Rv 的存在和强度。然后，我们实施了随机森林集成学习模型，根据生理和环境特征预测两种病原体的感染。Perkinsea 感染了所有采样无尾目动物的 32%，并且在 Ranidae 青蛙、较冷的月份、变态个体和与 Rv 合并感染的青蛙中，Pr 流行率显著升高，而在 ranid 青蛙和采集到的死亡个体中，Pr 强度显著升高。Ranavirus 总流行率为 17%，在 Ranidae 青蛙、变态个体、平均温度较高的地点和与 Pr 合并感染的个体中显著升高。Pr 流行率在整个月份、地区、生命阶段和物种中均显著高于 Rv 流行率。在地点方面，Pr 流行率与小龙虾流行率呈负相关，与 microhylids 的相对丰度呈正相关，但 Rv 流行率与任何测试的协变量均无关联。两种病原体的合并感染比单一感染更为常见，我们提出 Pr 感染可能会推动 Rv 感染，因为季节性 Rv 感染高峰紧随 Pr 感染高峰，随机森林模型发现 Pr 强度是解释 Rv 感染的主要因素。我们的研究阐明了佛罗里达州 Pr 的流行病学模式，并表明 Pr 可能被低估为无尾目减少的原因，尤其是在病原体合并感染的情况下。
