Using trial and error methodology that Thomas Edison could relate to, scientists have located a drug that may have the potential to treat prion diseases such as mad cow disease, scrapie and chronic wasting disease in animals, and diseases including Creutzfeldt-Jakob Disease, Fatal Familial Insomnia, and Kuru in humans, that "result from deposits of abnormal prion protein in brain tissue. Prion diseases are invariably fatal and no treatments are yet available." At this point testing is in mouse models and cell cultures.
Treatments exist for most other major classes of disease causing agents, such as bacterial infections, viruses, funguses, venoms, and parasites, but not for prions.
Prions are also worrisome because they are resistant to sterilization methods that destroy most other disease agents: "Prions are generally quite resistant to proteases, heat, radiation, and formalin treatments, although their infectivity can be reduced by such treatments." Strong acids in combination with higher than typically used heats are necessary to render them non-infectious.