它们最近才刚被确认为几种传染性疾病的病因。 其中包括疯牛病和克-雅氏病，后者通过排挤健康的脑细胞而致命。
They have only recently been recognized as the cause of several infectious diseases, including mad cow disease and Creutzfeldt-Jakob Disease, which kill by crowding out healthy brain cells.