The rise of the rosette agent in Europe: An epidemiological enigma

Abstract

International biodiversity assessments often overlook the role of emerging infectious pathogens in the decline of freshwater fish populations despite the many examples of emerging diseases in other more visible taxa on a global scale. Whilst the introduction of the rosette agent Sphaerothecum destruens in Europe remained an epidemiological enigma, recent findings have shown that this parasite arrived in Europe with the introduction of the healthy carrier Pseudorasbora parva from China nearly 60 years ago and its emergence went unnoticed for over 45 years despite its severe impact on European fish biodiversity. Recent reports on the host and pathogen phylogeny point towards an ancient host-pathogen co-evolution with direct implications on disease risk. Here, we postulate that the observed rapid population decline of native fish species following their infection with virulent strains of S. destruens has underpinned the rapid establishment of P. parva populations during the invasion process. We reviewed the existing evidence supporting the claim of an S. destruens' emergence worldwide and also suggest that the origin of the US strains is to be found among contaminated Asian Oncorhynchus tshawytscha living in sympatry with native Asian P. parva population. Finally, several important preventative steps are suggested as a way to manage the impact of S. destruens on local fish communities.

West Asian colonisation of topmouth gudgeon, Pseudorasbora parva (Teleostei: Gobionidae): Genetic admixture at the crossroad of Europe and east Asia

“…Accordingly, Hardouin et al. (2018), and Combe and Gozlan (2018) suggested that the P. parva introduction into Iran might have originated from an unsampled population in the Korean Peninsula, which was missing in their studies. Our results highlight the presence of an undescribed lineage in the Korean Peninsula, separated from the lineage/lineages found in China by 13 fixed substitutions (3.1% sequence divergence).…”

“…High densities of P. parva have severe and significant impacts on native trophic food webs, resulting in overlaps with native fishes trophic niche (Britton et al., 2010). Additional concerns include egg predation, hybridisation with endemic and rare species (Gozlan & Beyer, 2006; Konishi et al., 2003; Simon et al., 2011), facultative parasitism (Gozlan, Andreou, et al, 2010), and transmission of diseases such as the rosette agent Sphaerothecum destruens , which is a novel fungal fish pathogen responsible for the decline of many native fish populations (Andreou & Gozlan, 2016; Combe & Gozlan, 2018; Spikmans et al., 2020).…”

Txikispora philomaiosn. sp., n. g., a Micro-Eukaryotic Pathogen of Amphipods, Reveals Parasitism and Hidden Diversity in Class Filasterea

“…Finally, an indirect transmission cycle has been contemplated as well, given the generalist infectivity observed in T. philomaios and ichthyosporean parasites (Andreou et al 2012; Rowley et al 2013; Combe and Gozlan 2018). Copepods have been proposed as the missing intermediate host for the fish parasite I. hofferi , which infects herring and salmon species (Hershberger et al 2002; Gregg et al 2012).…”

Protein–protein interaction network: an emerging tool for understanding fish disease in aquaculture

“…Also, some chronic diseases caused by fungal and fungal-like pathogens exhibit no visible clinical symptoms which make their presence harder to trace and increase the spread of these diseases. For example, by hitch-hiking an invasive fish species (Pseudorasbora parva) as the carrier, the rosette agent Sphareothecum destruens (Mysomycetozoa)a generalist parasite capable of infecting a wide range of hosts with varying severityis now spread across Europe and a threat to most local fish species (Combe & Gozlan 2018). Most works on fungal and fungal-like pathogens in marine species, however, focus on the development of detection methods and pathological descriptions (Mendonca & Arkush 2004;Andreou et al 2012), with minimal work focuses on pathogens' protein constituent and mechanism of infection.…”