Prion diseases of the salival nervous system (CNS) are among the infectious diseases that cause a similar clinical course, histopathological hulgular, and the picture called spongiforin en-cephalopathy in humans and some animals (Table 1). Spongiform encephalopathies are pedestrian infections of the CNS and are caused by prions. Sigurdsson used the term "slow" infections to describe these diseases, which have long incubation, long clinical course, fatal outcome, pathology limited to single organ system and a limited number of sensitive co-iris. In these diseases, nbron loss, proliferation and hypertrophy in astrocytes, neuronal vacualization and weak inflammatory response are common features, the pathological picture is the same and the transmissible, no-rodejent.trati f disease is irritated.