contagion
Concise Oxford English Dictionary © 2008 Oxford University Press:
contagion /kənˈteɪdʒ(ə)n/
▶noun the communication of disease from one person or organism to another by close contact.
■ dated a disease spread by close contact.
– origin ME: from L. contagio(n-), from con- ‘together with’ + the base of tangere ‘to touch’.
'contagion' also found in these Oxford entries:

