Where did the virus come from, where will it go?
Pacific salmon and trout, and juvenile fish in particular, are vulnerable to infectious haematopoietic necrosis virus (IHNV), and its expanding spread is a real threat to both conservation efforts and the aquaculture industry. A new study has now analysed the incidences of IHNV throughout the Columbia River Basin and traced the potential routes of transmission, allowing the research team from the Cary Institute of Ecosystem Studies, USA, to map where the disease has been and where it could go in the future. The study suggested that infected adult fish returning to hatcheries were most likely to introduce the virus to juveniles, and infected juveniles play an important role in spreading the virus within hatcheries themselves. A better understanding of how IHNV spreads will be critical to stopping the virus in its tracks.