寄生虫,包括病毒,细菌,真菌,原生生物,蠕虫,和节肢动物,在动物王国中无处不在。因此,宿主经常同时感染一种以上的寄生虫。对这种共感染的评估对于疾病生态学至关重要,但是涉及非驯养动物的相关研究仍然很少。许多两栖动物正在衰退,它们通常有高度多样化的寄生动物。在这里,我们回顾了有关实地调查的文献报道,兽医案例研究,和两栖动物共同感染的实验室实验,我们总结了关于寄生虫之间宿主内相互作用的知识,哪些环境和内在因素会影响这些相互作用的结果,以及共感染对宿主有什么影响。现有文献是零碎的,模式非常多样化,因此,确定适合两栖动物中大多数宿主多寄生虫系统的一般趋势是困难的。添加剂的几个例子,拮抗,中性,不同寄生虫之间的协同作用是已知的,但是,某些高级分类群的成员是否通常胜过并超越其他分类群的影响尚不清楚。在许多情况下,不同寄生虫的到达顺序和暴露之间的时滞似乎从根本上塑造了竞争和疾病进展。第一个到达的寄生虫可以获得明显的生殖优势或诱导交叉反应免疫,但通过破坏皮肤和相关的防御(即,皮肤分泌物,皮肤微生物组)和免疫抑制,它也可以为随后的感染铺平道路。虽然也有例外,对宿主的有害影响通常随着共感染寄生虫物种数量的增加而加剧。最后,因为两栖动物是放热动物,温度似乎是影响共感染的最关键的环境因素,部分通过其对两栖动物免疫功能的影响,部分是由于它对寄生虫的生存和生长的直接影响。除了它们对我们理解生态模式和过程的重要性之外,关于共感染的详细知识对于设计和实施有效的野生动物疾病管理也至关重要,因此,专注于我们理解中发现的差距的研究代表了有益的研究途径。
Parasites, including viruses, bacteria, fungi, protists, helminths, and arthropods, are ubiquitous in the animal kingdom. Consequently, hosts are frequently infected with more than one parasite species simultaneously. The assessment of such co-infections is of fundamental importance for disease ecology, but relevant studies involving non-domesticated animals have remained scarce. Many amphibians are in decline, and they generally have a highly diverse parasitic fauna. Here we
review the literature reporting on field surveys, veterinary case studies, and laboratory experiments on co-infections in amphibians, and we summarize what is known about within-host interactions among parasites, which environmental and intrinsic factors influence the outcomes of these interactions, and what effects co-infections have on hosts. The available literature is piecemeal, and patterns are highly diverse, so that identifying general trends that would fit most host-multiparasite systems in amphibians is difficult. Several examples of additive, antagonistic, neutral, and synergistic effects among different parasites are known, but whether members of some higher taxa usually outcompete and override the effects of others remains unclear. The arrival order of different parasites and the time lag between exposures appear in many cases to fundamentally shape competition and disease progression. The first parasite to arrive can gain a marked reproductive advantage or induce cross-reaction immunity, but by disrupting the skin and associated defences (i.e., skin secretions, skin microbiome) and by immunosuppression, it can also pave the way for subsequent infections. Although there are exceptions, detrimental effects to the host are generally aggravated with increasing numbers of co-infecting parasite species. Finally, because amphibians are ectothermic animals, temperature appears to be the most critical environmental factor that affects co-infections, partly via its influence on amphibian immune function, partly due to its direct effect on the survival and growth of parasites. Besides their importance for our understanding of ecological patterns and processes, detailed knowledge about co-infections is also crucial for the design and implementation of effective wildlife disease management, so that studies concentrating on the identified gaps in our understanding represent rewarding research avenues.