Parasitic spores
Dispersed into the atmosphere
Carried on the winds
Inhaled, coursing through their blood
Taking seed within the brain

Cranial pressure increases
As the spores begin to grow
Microscopic roots bore deep into the cerebrum
Seizures rattle the body
Heartbeat accelerated
Involuntary screams escape the throat

Fever sets in, body temperature rises
All motor function becomes inhibited
Consciousness begins to fade

Cocooned in brain tissue
Sustained by human blood
Growth accelerates
Enlarging exponentially

Intracranial incubation

Thickly clotted blood oozes from their eyes
Liquefied brain tissue drains out from their ears
An exomorphic shell forms around their flesh
Insectiod limbs burst forth from within
Incubated larvae
Gains control of the host
Forced symbiosis commences