A degenerative disease that has consumed the bodies of the Vidiians for some two thousand years, driving them to harvest organs and tissue from other species to stay alive.
The Phage attacks genetic material and tissue, destroying organs and skin faster than they can be repaired. The Vidiians, once known for art and learning, have been reduced by it to a people of raiders with superb medical technology, who replace failing body parts with those taken from others.
The disease is introduced in the Voyager episode Phage, in which Neelix's lungs are stolen. It returns in Faces, where a Vidiian scientist splits Torres into human and Klingon halves in the hope that Klingon DNA resists it, and in Lifesigns, in which the Doctor treats the afflicted physician Danara Pel. Deadlock shows a Vidiian boarding party harvesting a duplicate Voyager's crew.
In the later episode Think Tank, the group of that name claims to have cured the Phage.