Assessment over time of the infectivity of gill-derived and seawater dispersed Neoparamoeba permaquidensis (Page, 1987)

A laboratory infection trial tested if Neoparamoeba pemaquidensis, the protozoan responsible for AGD, remained infectious for up to 14 days when out of contact with host tissues. In the infection trial, 14 Atlantic salmon (Salmo salar) were exposed to gill-derived paramoebae, which had been out of contact with hosts for up to 14 days. At the conclusion of the trial fish tested immunodot blot positive and were positive for histology. This implies that infection occurs from water to fish and the zone of infection around salmon farms may be very extensive.