Spiroplasmas are also within the size range of the agent that transmits CJD and other transmissible Spongiform encephalopathies. Spiroplasmas will pass through a 50 nm-pore filter. The transmissible agent's size has been determined to be 42 nm.Spiroplasmas, are present in the hemolymph of almost all insects; there probably are several million strains. They can also cause diseases in plants but are usually associated with a vector. For example, a leaf hopper carries a spiroplasma that infects orange trees.