For anyone interested, the aliens from the "Conspiracy" episode have appeared in other Trek media:
The parasites have had a number of appearances in the DS9 relaunch significantly building on their history and motivations:
Sins of the Mother (The Lives of Dax short story)
Set before Conspiracy establishing the Federation's first contact with the parasites.
Mission Gamma (miniseries)
The Mission Gamma series sets up a parasite attempt to take over the Bajor Sector.
Unity continues the story begun in Mission Gamma.
The Broken Moon (TNG comic)
The parasitic aliens have also appeared attempting to start a civil war on the planet Onglaatu in Broken Moon.