Toluncan ague

From Memory Alpha, the free Star Trek reference

The Toluncan ague is a type of influenza.

Every flu season on the USS Voyager, Neelix became convinced that he had Toluncan ague. Rather than arguing with him, the Doctor would simply give him a placebo. (VOY: "Virtuoso")

"Ague" is an old term for fever, usually from malaria.