This mysterious ailment appeared some time after the main infection and many believe it is a highly infectious mutated form on the same disease. Unlike its counterpart, this one has symptoms such as a burning fever, severe lethargy, and red splotches which appear on the skin. Also unlike its counterpart, it kills if left untreated for too long. The good news is that it can also be cured and treated by those with the knowledge and skill. The bad news is that it requires the knowledge and skill to be cured or it will prove fatal.
Not all zombies carry the Blood Plague so exposure is fairly rare and it is quite easy to tell the Plagued zombies from their counterparts. Plague Zombies are crimson in color with glowing red eyes and their skin is covered in oozing pustules so even in the dark they are difficult to miss. When handled with care or outright avoided, a survivor can walk away from an encounter with these creatures without contracting the Blood Plague.
There is no known information on where or how this came to be at this time.