During the Galactic War that raged between the Galactic Republic and the re-established Sith Empire, the scientist Sannus Lorrick, who was living in exile, triggered an outbreak of the rakghoul plague within the Tion Hegemony. Before quarantine protocols could be enacted, numerous planets succumbed to the infectious disease, with the planet of Kaon being the fifth to fall to the rakghouls. The source of the plague was ultimately traced to Lorrick's laboratory located on Ord Mantell, where he met his end. However, before his demise, Lorrick managed to infect the passenger ship Stardream, which subsequently crashed on Tatooine, resulting in a galaxy-spanning emergency.
The outbreak mirrors the events that unfold in the Flashpoint: Kaon Under Siege featured in Star Wars: The Old Republic. This flashpoint can be accessed by both the Empire and Republic factions, leaving the canonical responsibility for dispatching the strike team ambiguous. While the makeup of the strike team doesn't affect the storyline, it's generally believed that an Imperial strike team would opt for the dark side choice of eliminating Melarra at the conclusion of the battle, whereas a Republic strike team would likely choose to set her free.