Achira is a disease-spreading entity featured in the first two episodes of Extreme Ghostbusters.
Achina is able to pose as other's deceased loved ones. When Kylie Griffin uses a ghost beacon, and inadvertently summons Achira while trying to summon her dead grandmother. Achira poses as her grandmother long enough to possess her.
Achira then spreads disease to others until Eduardo Rivera, Garrett Miller, and Roland Jackson blast it with proton streams. They fail to trap her though. When they report back to Egon Spengler, he modifies a new trap for Kylie to wear on her back. With the new equipment, they finally manage to trap Achira.