The spread or transmission of such a disease.
The spread of (initially small) shocks, which initially affect only a few financial institutions or a particular region of an economy, to other financial sectors and other countries whose economies were previously healthy.
The passing on of manners or behaviour through a closed community or household.
A recession or crisis developed in such manner.
A disease spread by contact.
A toxin that has had its toxic properties removed, but retains its ability to generate an immune response.