In September 1988, chinook salmon at a marine net pen site were observed with clinical signs of inappetence, slow swimming, and non-response to divers. More fish than expected were found dead at the bottom of the pen, although some resumed slow swimming when handled. Gross changes observed were confined to the eyes, and lesions included corneal opacity, cataract, hyphema and hypopyon. Tapeworm metacestodes were found within the globe on hemisection of affected eyes, with retinal separation and folding requently observed in association with the presence of the parasite. The parasites were identified as metacestodes of Gilcfuinia squali, a trypanorhynch that has its adult stage in the spiral valve of the dogfish Sqfualus acanthias. Although the reminder of the life cycle of this parasite is unknown, the salmon were likely infected by consuming marine crustacean first intermediate hosts.

Histopathological changes in infected eyes included uveitis, anterior synechia, cataract, necrosis of lens, retinal necrosis and separation, and optic neuritis. Although the ocular lesions were not thought to be sufficient to cause acute mortality, post mortem examination did not disclose further lesions in affected fish and the parasite was not found on dissection of eyes from healthy fish. Outbreaks of Gilquinia associated mortality have since been reported annually in early Autumn from a number of fish farm sites in the Quadra Island and Sechelt regions of the west coast of British Columbia. Case fatality rates can reach 10%, and further investigation of the pathogenesis and epidemiology of this disease is needed.