"The Houses and Order are currently scrambling to find ways of identifying Nomad Thralls, however this has so far been stymied by the lack of obvious biological changes".
And before that
"This Nomad form can possess the human body, devouring key organs and wrapping itself around the central nervous system. Such parasitism makes the host dependent on the Incubus, and removal is invariably fatal."
I would say this gives a clear way of detecting infiltrators. Of course, if you refer to "thralls" then it is probably ok, but then again, thralls (if you change the lore to include those) must operate close to the infiltrator, meaning it is possible to sort out an infiltrator even using regular OSINT.
