Dr. Holló Ferenc szerk.: Parasitologia Hungarica 3. (Budapest, 1970)

our epidemiological studies on assumed healthy population samples in Budapest, and in the counties of Veszprém and GyőrSopron. The epidemiological findings of this survey, carried out on more than 5000 people, are reported here. Materials and Methods Toxoplasmin used throughout this study was derived from Toxo plasma gondii strain maintained in mice. Antigen was produced by freezing the protozoa, and, on the basis of biological titration, an appropriate concentration was prepared using 0,85 # saline diluent. Phenol was added up to 0,3 # of the solution for preservation. In contrast to the very comparable tuberculin test international agreement on the design of the PST has not yet been reached. Thus, recommendations for the tuberculin skin test suggested by WHO (WHO, 1963) were adopted for the PST. Injections were made with special ml Omega-Mikrostat Hypodermic Syringes (Omega Precision Medical Instrument Co., Inc. Parsaic, N.T.) using 10 mm needles of No. 25-26. All instruments were boiled in distilled water for 30 minutes before use. Injection was made on the volar surface of the upper third of the forearm. The skin was cleaned with alcohol. At the intended site of injection the skin was slightly stretched along the axis of the forearm. Then, the needle was inserted into the superficial layer of the skin at an angle of 20-30 degrees. (Care must be taken during insertion to avoid touching the plunger of the syringe.) Subsequently, 0,1 ml of toxoplasmin was injected slowly. Then, pressure was taken off the plunger and the needle was removed. The liquid injected resulted in a small, sharply demarcated, anaemic swelling on the skin with a visible puncture hole produced by the needle. The characteristic swelling was not produced if the point of the needle had been inserted in a deeper layer. The correct reading and eva-