Transmission of Salmonid Whirling Disease by Birds Fed Trout Infected with Myxosoma cerebralis

Abstract

Mallard ducks Anas platyrhynchos and a black crested night heron Nycticorax nycticorax were fed trout infected with M. cerebralis (Hofer). Feces from the birds were deposited in troughs containing M. cerebralis-free mud as well as in 1 trough without mud. Spore suspensions were also added directly to mud in 1 trough and to another trough without mud. Susceptible rainbow trout Salmo gairdneri developed whirling disease in all troughs containing mud contaminated with M. cerebralis but remained free of infection when exposed to M. cerebralis in troughs without mud. This demonstrates the possibility of bird transmission of the organism causing whirling disease to previously non-contaminated waters.