Green’s Dictionary of Slang

(UK prison) the illusion, fostered by too long a career in the prison service, that every prisoner is about to attack one for no other reason than that one is a warder.

1950

P. Tempest Lag’s Lex. 51: convictitis. One of several ‘prison diseases’. A prison officer after many years of service is spoken of as suffering from ‘convictitis’ when his nerve goes and he begins to imagine that every convict he sees is about to attack him.