Contagium vivum fluidum was the phrase given to one of the following.

M.W. Beijerinek (1898) demonstrated that the extract of the infected plants of tobacco could cause infection in healthy plants and called the fluid as   (infectious living fluid). Viroids are infectious RNA molecules that cause diseases in plants such as Potato spindle tuber disease. Prions are misfolded proteins which are similar to viruses in size and cause neurological diseases in animals such as Bovine Spongiform Encephalopathy or Mad Cow disease and its analogous variant causes Cruetzefeldt Jacob disease in man. Bacteria cause diseases like cholera, typhoid, tetanus, citrus canker etc.