The plague was designed to attack the Alterra's highly advanced physiology. The more advanced the victim...the more deadly the plague became.
The plague did not kill the Alterra quickly. Their immune systems(assisted by medical technology) fought the virus continuously, but did not prove strong enough to defeat it...but the internal battle did buy them years in which to search for a cure.
The time from infection till death varied depending on the individual, but on average it ranged from a few years to over a century for the more hardy individuals. During that time any and every attempt to find a cure was conceived, explored, and ultimately failed resulting in the eventual death of every single Alterran in existence...save one.
Point of ContaminationEdit
When the plague first infected the Alterra, they were unable to pinpoint the source of the contamination. It appeared on different planets, in different galaxies seemingly at random. The Alterra eventually sought to create a time machine to send a research team back in time to try and identify the source of the plague, but the machine was a failure and they eventually abandoned the project.
The Alterra could never find the source of the contamination because it existed within another dimension. The ascended beings within the Ascended Empire directly infected the Alterra, circumventing all attempts at quarantine. Wherever the Alterra went to escape the plague, the Empire followed, quietly reinfecting them even when they transferred their consciousnesses into cloned bodies...which would then mysteriously become infected as well.
Knowing that they were doomed, the Alterra sought out a means to circumvent the plague and reestablish their civilization while some of their kind attempted to escape death through an obscure legend known as Ascension. Many did achieve this escape, never to be heard from again, while the rest devoted themselves to the Legacy Project which was intended to beat the plague by devolving their race to the point where the plague would have no effect on them, thus 'escaping' it through another means.
Aeria, the lead researcher on the plague project worked with the Nox to develop a cure up until the time she neared death. In order to preserve a slim hope for survival(and to provide the Nox with a permanent research specimen) she suspended herself inside a stasis pod until Ryan Stevenson revived her millions of years later with a cure. She subsequently ascended moments thereafter at the behest of her former brothers and sisters over Stevenson's hurried objections.
When the Legacy Project came to fruition, the first of the new Alterra immediately sought out a cure to the plague, knowing full well the Ascended Empire's involvement and the high risk of a second plague when they once again took notice of the redeveloping Alterran civilization.
The key came, ironically, from the accidental infection of a number of Humans from an Alterra that had been trapped and preserved within a block of ice in Antarctica. Unfortunately a sample of the plague survived within her, whereas the rest of the Ascended Empire's bioweapon had disappeared from the galaxy by the ravages of time(and lack of hosts).
That surviving Alterra managed to cure the primitive Humans save one. That one was Jack O'Neill, who was cured by the implantation of a Tok'ra symbiot. Knowing of the story, Stevenson sought out the Tok'ra to learn the secret of their healing ability.
Striking a deal with a Tok'ra called Anise, Stevenson and the Nox were successful in creating an upgrade to the Alterran immune system that would provide them with the anti-viral boost they required in order to become strong enough to overcome the plague naturally, without any medical attention required.
Stevenson made the genetic modifications to his own body, then deliberately infected himself with a sample of the plague contained within Aeria's body. When he successfully fought off the infection he revived Aeria, and with the help of Stevenson and an Alterran Regenerator she slowly fought off the plague within her...making Aeria the one and only mortal survivor of the plague.