Start a casual game with the necroa virus.
You must save up 49 DNA points, then evolve the following symptoms:
Insomnia
Fever
Photophobia
Delirium
Cytopathic Reanimation
And the following ability:
Regenerative Activation
Once you've done that, exit the disease screen, wait a couple in-game-days, press
, hover over your starting country, and finally press
to use the reanimate ability.
The achievement should unlock.