Abstract：
Global climate change is altering the abundance and spread of many aquatic parasites and pathogens. Proliferative kidney disease (PKD) of salmonids caused by the myxozoan Tetracapsuloides bryosalmonae is one such emerging disorder, and its impact is expected to increase with rising water temperature. Yet, the distribution and prevalence of T. bryosalmonae in Northern Europe remain poorly characterized. Here, we studied 43 locations in 27 rivers in northernmost Norway and Finland to describe T. bryosalmonae infection frequency and patterns in 1389 juvenile salmonids. T. bryosalmonae was discovered in 12 out of 27 rivers (44%) and prevalence ranged from 4.2 to 55.5% in Atlantic salmon and from 5.8 to 75% in brown trout among infected rivers. In sympatric populations, brown trout was more frequently infected with T. bryosalmonae than was salmon. Age-specific parasite prevalence patterns revealed that in contrast to lower latitudes, the infection of juvenile fish predominantly occurs during the second summer or later. Temperature monitoring over 2 yr indicated that the mean water temperature in June was 2.1 to 3.2°C higher in rivers containing T. bryosalmonae compared to parasite-free rivers, confirming the important role of temperature in parasite occurrence. Temporal comparison in T. bryosalmonae prevalence over a 10 yr period in 11 rivers did not reveal any signs of contemporary parasite spread to previously uninfected rivers. However, the wide distribution of T. bryosalmonae in rivers flowing to the Barents Sea indicates that climate change and heat waves may cause new disease outbreaks in northern regions.
摘要：
全球气候变化正在改变许多水生寄生虫和病原体的丰度和传播。由粘液动物Tetracapsuloides苔藓引起的鲑鱼增生性肾脏疾病（PKD）是一种这样的新兴疾病，其影响预计会随着水温的升高而增加。然而，北欧苔藓沙门氏菌的分布和患病率仍然很差。这里,我们研究了挪威和芬兰最北端的27条河流中的43个地点，以描述1389种幼年鲑鱼的苔藓沙门氏菌感染频率和模式。在27条河流中的12条（44％）中发现了苔藓沙门氏菌，在受感染的河流中，大西洋鲑鱼的患病率为4.2％至55.5％，褐鳟鱼的患病率为5.8％至75％。在同胞群体中，褐鳟鱼比鲑鱼更容易感染苔藓沙门氏菌。特定年龄的寄生虫流行模式表明，与低纬度相比，幼鱼的感染主要发生在第二个夏天或更晚。超过2年的温度监测表明，与无寄生虫的河流相比，含有苔藓沙门氏菌的河流6月份的平均水温高2.1至3.2°C，证实了温度在寄生虫发生中的重要作用。在11条河流中10年的苔藓沙门氏菌流行率的时间比较没有发现任何当代寄生虫传播到以前未感染的河流的迹象。然而,在流向巴伦支海的河流中，苔藓沙门氏菌的广泛分布表明，气候变化和热浪可能会在北部地区引起新的疾病爆发。
