First detection of Sphaerothecum destruens in salmonids in France

摘要

Sphaerothecum destruens is a parasite infecting a wide range of host species. Its pathogenicity has been shown in Chinook salmon (Oncorhynchus tshawytscha) and Atlantic salmon (Salmo salar) under natural conditions and experimentally in rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta) and a variety of cyprinid fish. This article describes two clinical cases of S. destruens infections in rainbow trout and brown trout using symptomatology, histology and PCR amplification of a 18S rRNA gene fragment of the parasite. Recently the role of the topmouth gudgeon (Pseudorasbora parva) as an asymptomatic carrier in France has been stated. Here we report two cases of natural infections of salmonids in France. Given the multiple co-infections, the exact impact of S. destruens in these cases was difficult to establish. However our results suggest that S. destruens represents a potential emerging risk for farmed trout in France.