Bloodburn was a rare, chronic, and often terminal illness of the blood that befell starship pilots. In the most serious cases, fevers would form and graduate in intensity to the point of overheating and death. The precise cause was not known, but it was known to be a result of space travel, appearing most commonly in younger pilots. Pilots found to be affected by bloodburn were commonly grounded. The human Greer Sonnel ended her racing career due to bloodburn.