The Styx field-trial. A study on the application of control measures against hydatid disease caused by Echinococcus granulosus.

An assessment was made of the effectiveness of the generally accepted methods recommended for controlling hydatid disease during the course of a field-trial, initiated in 1943 in an isolated region of New Zealand. The results obtained during the first 21 years are described.Basically, the trial was an attempt to compare the effectiveness of a general public health educational programme and an anthelmintic programme using arecoline hydrobromide for treatment of dogs with that of a specific educational programme using this compound as a diagnostic agent.Arecoline hydrobromide was found to be too uncertain in its action to be of practical value as an anthelmintic. The development of diagnostic techniques, described in this paper, made it possible to use the compound for diagnostic purposes and thus for educational purposes, since each dog could be examined for tapeworms in the presence of the owner.Using changes in the annual prevalence rate in sheep of the cysts of E. granulosus and those of T. hydatigena as the principal indicators, the conclusion has been reached that the specific diagnostic approach achieved more success than the general educational and treatment programme. The principal reason for this appears to be that the former approach induced a greater awareness in owners of the need for strict management to prevent dogs gaining access to infective raw offal than that stimulated in the community when the dogs were dosed but not examined.