The effect of ionizing radiation on the viability of Trichomonas vaginalis.

1. The effects of continuous gamma radiation on the viability of Trichomonas vaginalis (ATCC 30001) were assessed by a colony count technique. 2. A triphasic survival curve showed an initial shoulder (Dq) of 3 Gy followed by three linear curves with D0 values of 34, 300, and 90 Gy. 3. Sterilization of 10(6) cells/ml occurred from 1600 to 1800 Gy of radiation. 4. Population growth, subsequent to radiation exposure of 17-100 Gy, showed an increased lag time followed by a faster rate of growth, compared with unirradiated cells. 5. Trichomonas vaginalis is more sensitive to ionizing radiation than free-living protozoa and appears as radiosensitive as those parasitic protozoa examined in radioattenuation experiments.