I know it's not, but that first image reminds me of Cryptococcus neoformans in an india ink stain, the halo's being formed by the capsule round the yeast cells. Infection, which can include meningitis, can also be acquired from pigeon/dove droppings which fits with Faith's references about the holy spirit descending as a dove.
As for the second picture, the 'halo' is obviously a tapeworm egg. The pork tapeworm Taenia solium can encyst in other regions of the human body, including the brain where it can cause neurological problems, not unlike demon possession.
Edited by Malcolm, : No reason given.