About 570 planets wiped out or abandoned during Hlekkarian Plague, TE 430-440 (AD 2583-2593)
A vaccine to Hlekkarian Plague was developed in 440 on Taglierre, and spread by Imperial Navy. Within four tendays, the Plague was declared over.
The Hlekkarian Plague was a particularly virulent form of influenza, with all of the attendant respiratory symptoms. However, the Plague organism had the ability, in some cases, to tailor itself to a particular host over time. Therefore, episodes of Plague had a tendency to recur, growing more virulent with each return. Individual episodes usually started at six to twelve days, then increased in duration with each subsequent episode. Recurrences came on the order of thirty to ninety days apart, although that time period tended to lengthen as the disease progressed.
The particular dread of the Hlekkarian Plague was that one could never be sure that one was rid of it. At any time, it could return, worse than before . . . and continue returning, until finally one died.