Noun
(Britain, slang) A fictitious, highly infectious disease; often used in the phrase "the dreaded lurgi", sometimes as a reference to flu-like symptoms
(Britain, slang) Any uncategorised disease with symptoms similar to a cold or flu that renders one unable to work.
Source: en.wiktionary.orgIn the episode "Lurgi Strikes Britain", Spike Milligan introduced the fictional malady of Lurgi (sometimes spelled Lurgy), which has survived into modern usage to mean any miscellaneous or non-specific illness (often preceded by the adjective "dreaded"). Source: Internet