KINETICS IN THE THERMODESTRUCTION OF CYSTS OF ENDAMOEBA HISTOLYTICA IN WATER

Abstract

With respect to thermal destruction of cysts there is a semilog-arithmic relationship between the increase in the most probable cysticidal contact times and the lowering of the temps. at which the cysts were exposed. The value of the energy of activation for the thermo-destruction of cysts is 134,000 calories. At a fixed temp. the increase in cyst concn. exhibits a semilogarithmic relationship with the increase in the most probable cysticidal contact time. At 45[degree]C this relationship can be expressed by the equation.[image].where t2 and t1 are the most probable.cysticidal contact times required for the cyst concns. a2 and a1. This expression shows a 40-min. increase in the most probable cysticidal contact time for every 10-fold increase in cyst concn. In determining the effect of change in cyst concn. on cysticidal efficiency, the total number of cysts per inoculum should be used as a unit of expression, since the positiveness of the culture depends on the number of cysts inoculated. The more cysts the inoculum contains, the greater the chance that the inoculum will have viable cysts. For the destruction of amebic cysts in water and on vegetables, a treatment of heating the water to 50[degree]C for 30 min. appears to provide a wide margin of safety and does not harm the vegetables.