This could be a reference to the Spitter Zombies from the Left 4 Dead video games. Spitters are thin female zombies that excrete an acidic substance from their mouths. Stepping in the substance will cause the player to lose health, so Spitters must be killed from a distance.
|Symptoms in Plague Inc. and Plague Inc: Evolved.|
|Symptoms ● Symptoms (Neurax Worm) ● Symptoms (Necroa Virus) ● Symptoms (Simian Flu) ● Symptoms (Shadow Plague)