Green’s Dictionary of Slang

lurgi n.

also lergy, lurgy
[popularly attrib. to the writers of The Goon Show (1953–60), but the EDD cites lurgy, idleness, loafing + lurgy-fever, the ‘disease’ of idleness. The OED adds the synon. fever-lurden, fever-lurgan, ult. SE fever + lurdan, ‘a general term of opprobrium, reproach, or abuse, implying either dullness and incapacity, or idleness and rascality; a sluggard, vagabond, “loafer”’]

1. [1940s+] any unspecified but deleterious disease or ailment; esp. as the minatory phr. dreaded lurgi.

2. in fig. sense.