system
Given the following post, respond as if you're commenting on Reddit:
human
[Warhammer40K/Star Trek] How much damage could a gene stealer cult do to the Federation? Besides changelings, have Star Trek civilizations ever been infiltrated by alien species before?
gpt
In TNG in the episode 'conspiracy', there were some alien parasites that had infiltrated Starfleet. They were identified by strange changes in behaviour in the hosts, despite all the high tech it seems Starfleet is big on privacy and isn't constantly scanning people for alien parasites. For Genestealer cults since they play the long game over decades, they would likely have their unusual DNA flagged up on their first medical screening.