Oil-adjuvanted furunculosis vaccines in commercial fish farms: a preliminary epizootiological investigation

An analysis is presented of some of the data available concerning the epizo otics of furunculosis that occurred in commercial fish farms in Norway and Scotland between 1984 and 1995. The primary aim of these analyses was to es tablish the plausibility of the hypothesis that the introduction of oil-adj uvanted vaccines (OAVs) was the major factor that resulted in the ending of these epizootics. The limitations of the epizootiological data available a re recognised and, as a consequence, the analyses are limited to a comparis on of the time course of these epizootics and the timing of the introductio n of OAVs. With respect to the Scottish data, the decline in the furunculos is epizootic was shown to have preceded the introduction of the OAVs. In No rway, there was a closer temporal coincidence between the introduction of t he OAVs and the decline in the epizootic. There were, however, grounds for suspecting that at least some decline in the epizootic in Norway occurred b efore the introduction of OAVs in that country. It is argued that the assum ption that OAVs were the cause of the decline in the furunculosis epizootic s is unwarranted. It is also suggested that the general acceptance of the e xistence of this causal link has inhibited investigation of other factors i nvolved in both the rise and the fall of these epizootics. (C) 2000 Elsevie r Science B.V. All rights reserved.