The Tarkalean flu was an infectious, viral-borne disease originating on the planet Tarkalea.
In 2377, while Tuvok was undergoing the effects of pon farr, Tom Paris examined him and deduced the condition. To protect Tuvok's dignity (among Vulcans pon farr was a very private matter), Paris told him that he would inform Captain Janeway that the Vulcan was suffering from a mild case of this affliction, allowing him time to get through it undisturbed in his quarters. The ruse proved to be unsuccessful, as Janeway remembered that the last time Tuvok had the "Tarkalean flu" was exactly seven years before; pon farr occurred once every seven years. (VOY: "Body and Soul")