"obsession with the problems of one's locality and consequent failure to see big pictures," 1943, U.S. World War II jargon, originally of military strategists, from local (adj.) + transferred use of medical suffix -itis.
late 14c., "pertaining to position," originally medical: "confined to a particular part of the body;" from Old French local "local" (13c.) and directly from Late Latin localis "pertaining to a place," from Latin locus "a place, spot" (see locus).
The meaning "limited to a particular place" is from c. 1500. Local color is from 1721, originally a term in painting; the meaning "anything picturesque" is from c. 1900. Local option (1868, American English) is from the prohibition movement: "the right of a community to vote on whether to allow the sale of intoxicating liquor there." Local talent "attractive women thereabouts" is from 1947 in UK slang; earlier it was used in reference to entertainment acts in shows, radio broadcast, etc.
Thus, with the local talent, we have many factors which help "sell" is in quantities far beyond what the commercial market would carry. Pride in children, interest in relatives and friends, and pride in locality all give impetus to the development of home talent. [Horace Boies Hawthorn, "The Sociology of Rural Life," 1926]
word-forming element in medicine denoting "diseases characterized by inflammation" (of the specified part), Modern Latin, from Greek -itis, feminine of adjectival suffix -ites "pertaining to." Feminine because it was used with an implied nosos "disease," a feminine noun; especially in arthritis (nosos) "(disease) of the joints." Arthritis (16c.) was one of the earliest appearances of the suffix in English and from it the suffix was abstracted in other uses.
<a href="https://www.etymonline.com/word/localitis">Etymology of localitis by etymonline</a>
Harper, D. (n.d.). Etymology of localitis. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/localitis