Emergence of the Fungal Rosette Agent in the World: Current Risk to Fish Biodiversity and Aquaculture

Abstract

The emergence of pathogenic fungi is a major and rapidly growing problem (7% increase) that affects human and animal health, ecosystems, food security and the economy worldwide. The Dermocystida group in particular has emerged relatively recently and includes species that affect both humans and animals. Within this group, one species in particular, Sphareothecum destruens, also known as the Rosette agent, represents a major risk to global aquatic biodiversity and aquaculture and has caused severe declines in wild fish populations in Europe and large losses in salmon farms in the USA. It is a species that has been associated with a healthy carrier for millions of years but the host has managed in recent decades to invade parts of Southeast Asia, Central Asia, Europe and North Africa. In order to better understand the emergence of this new disease, we have for the first time synthesised current knowledge on the distribution, detection, prevalence of S. destruens as well as the associated mortality curves, and the potential economic impact in countries where the healthy carrier has been introduced. Finally, we propose solutions and perspectives to manage and mitigate the emergence of this fungus in countries where it has been introduced.