[Name] Harvester Virus [Source] Star Trek: Deep Space Nine: "Armageddon Game" [Symptoms] 
Described as a "nanobiogenic weapon", the Harvesters were developed by the T'Lani and Kellerun from a small synthetic virus that was, itself, very lethal; the deadly and much feared weapon used during their centuries-long war killed by disrupting the victim's genetic structure, and had completely devastated the entire population of T'Lani III. So feared was this virus, that even after peace was made and the harvesters were disposed of in a ten-year project, the two governments secretly made plans to assassinate the scientists who worked on the project, fearing what might happen if they were ever remade.