A degenerative and incurable blood disease caused by exposure to metreon isotopes which attacks victims on the molecular level and may lie dormant for years. Once manifested, it causes a victim's atomic structure to undergo fission and the cells subsequently disintegrate. Haakonian Dr. Jetrel says his guilt as creator of the Metreon Cascade weapon, which unleashed the radiation on the Talax moon Rinax, led him to treat surviving searchers like Neelix before his death.