Rugalan fever

From Memory Alpha, the free Star Trek reference.

Rugalan fever is a disease that Dax's fourth host Audrid's daughter Neema had. Neema would spend two weeks in the hospital with it, two weeks in which Audrid read read all seventeen volumes of Down the River Light. (DS9: "Nor the Battle to the Strong")

In the shooting script, this illness was called Regulan fever.