A preliminary investigation of alternatives to fumagillin for the treatment of Loma salmonae infection in rainbow trout

The effects of the following six treatments against Loma salmonae, a micros poridian gill pathogen, were examined in rainbow trout: fumagillin (high do se), pyrimethamine + sulphaquinoxaline, albendazole, amprolium, fu magillin (low dose), and metronidazole. The fish were infected by mouth and the tre atments were administered at intervals for a period of several weeks. The r esults were assessed on the basis of (1) delay in the formation of xenomas, and (2) the number of xenomas per gill arch. The first five treatments, in descending order of efficacy, delayed the formation of xenomas (P<0.01), b ut metronidazole had no such effect. Fumagillin (high or low dose) and albe ndazole both reduced the number of xenomas present 10 weeks after infection (P<0.01), but the other three treatments did not do so. From these results , both fumagillin and albendazole appeared to be of potential value in cont rolling L. salmonae infection in trout. (C) 1999 Harcourt Publishers Ltd.