Silicon-based virus
From Memory Alpha, the free Star Trek reference
A silicon-based virus was a silicon-based lifeform that infected Hoshi Sato and Commander "Trip" Tucker from the NX class starship Enterprise in 2154 while they were orbiting a planet under Organian observation. The virus had previously infected Cardassian and Klingon crews, although the latter was killed by their commanding officer. (ENT: "Observer Effect")
