Citation le Gouvello R, Pobel T, Richards R & Gould C (1999) Field efficacy of a 10-day treatment of fumagillin against proliferative kidney disease in rainbow trout Oncorhynchus mykiss. Aquaculture, 171 (1-2), pp. 27-40. https://doi.org/10.1016/S0044-8486%2898%2900430-X
Abstract Proliferative kidney disease (PKD) of salmonid fish is an endoparasitosis due to infection with an, as yet, unclassified myxosporean parasite, the so-called `PKX'. Malachite green and fumagillin are the only chemotherapeutants capable of controlling this disease. The efficacy of a single 10-day treatment of fumagillin, orally administered at 3 mg kg body weight (BW)-1 day-1 was assessed in 14 field trials conducted during the summers of 1994 and 1995 in trout farms located in France and the United Kingdom (UK), using populations of juvenile rainbow trout, naive to PKX infection. Each population was divided into a treated group and an untreated control group, that were run in parallel. The first day of medication (D0) was determined by collection for examination of a random sample of 50 fish within each population prior to medication. Depending on the frequency of PKX cells in kidney imprints from these samples (2-8%, 10-30%, or >30% frequency), fumagillin treatment was commenced at either 15-21 days, 7-15 days, or immediately after parasitic examination. Assessment of the treatment efficacy was based upon comparisons between treated and control groups of the distribution of renal hypertrophic lesions, final survival rates, total losses in body weight and food conversion ratios (FCR). The tolerance to the product was quantitatively assessed by comparing the intermediate survival rates among groups on D35; the end of a critical post-medication period identified in previous studies. Most treated fish exhibited significantly fewer severe lesions (mean reduction in frequency of 59.1%). A mean relative percent survival (RPS) of 36.7% in PKD mortality was obtained. RPS was higher in moderate cases of PKD. The mean difference of overall survival rates was +7.8% in favour of treated fish. The mean reduction of weight loss was 32% in treated fish compared to controls. An improvement of FCR was detected when a very severe PKD occurred in the farm. Overall, this study confirms that fumagillin is a safe and effective treatment for PKD in Salmonidae when administered at 3 mg kg BW-1 day-1 for 10 days during the PKD incubation phase.