Studies on Pleistophora Infection in Eel, Anguilla japonica-II.

Preliminary Tests for Application of Fumagillin

Abstract

In the present study, we investigated the dosage and treatment period of fumagillin for the practical control of Pleistophora infection in eel.
We administered fumagillin to orally infected eels at 1.8 to 64.0 mg/kg B.W./day in feed for 5 to 90 days. The administration was started immediately after inoculation. The rate of infection during the medication was controlled within the range of 0-15% when administered at 5 mg/kg B.W./day for 60 days, 7.2 to 14.4 mg/kg B.W./day for 30 days or 50 mg/kg B.W./day for 20 days. Intermittent administration for a total of 20 days (5 days on, 5 days off) at 50 mg/kg B.W./day was also effective. However, when the administration was started from 6 days or more post inoculation, the effect of fumagillin was insufficient. Although fumagillin could inhibit the further development of lesions when administered to symptomatic fish, the development of the disease occurred again about one month after ceasing drug administration.
The disease spread to healthy fish when raised with diseased eels in the same aquarium and fumagillin was also found to be useful for prevention of the contagion.
Fumagillin had a significant effect on preventing the development of the parasite in the fish which had been held under low temperatures such as 13-14°C over 30 days after inoculation, if the drug was administered before the parasite began to develop by temperature elevation.
We discussed whether fumagillin was useful for the practical control of the microsporidiosis in eel culture.