The Juicer Plague, or Vampire Plague turns normal woodland creatures into plant juice suckers of ravenous intensity, and shocking amounts. The animals grow in size, and swell....until near the end they get overwhelmed with a desire to bite other animals (thus spreading the disease), and then they explode throwing disease tainted gore in a wide circle. They leave behind them fields of crippled plants.
If a wolf were to eat a plague suffering rabbit, the wolf would be infected as well. If such a creature were to bite a human, the human would not be infected (except if certain conditions of a dual-genomic nature became active.)
The virus is strictly for attacking plants, but it has a dual-genomic structure (which probably means that some clueless folks in this world are going to yell 'its mutated'). In a dessert environment without enough plant matter, it shifts its targets to animals and people. Its gene structure has two expressions that are equally valid, and which one is active is determined by the presence of sufficient amounts of foilage which is its preferred diet.
To avoid infection, a bit animal must make a Simple Resistance check. For every additional bite the Juicer or Vampinimal, gains a +4 penalty to their dice roll. An animal contacting the gore after an explosion must make a Simple check -3.
Infected creatures get a plus @2 to their strength. They dislike bright lights, and tend to stay in the shade during the afternoon hours.
One infected creature can on average destroy a hundred square yards of crops or lawn in a ten minute period. This is a ten yard by ten yard space, about the size of a suburban front lawn. Woodland is one-half to one-fourth the speed depending on tree size and density of trunks.
On average, they find a new 'recruit' every thirty minutes. After each ten minute period, roll a Resistance Simple Check. Failure means the creature loses a stamina mark. When Stamina reaches 0@5, the creature explodes.
Lower Key Variant:
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A lower-key, more insidious form of the plague could be exactly the same minus the parts about explosive death and herbivores biting other animals. The herbivores would still die (exhaustion, probably), and the plague would still spread up the food chain. It would be somewhat slower acting because of the absence of two out of three vectors (bite from infected animal, infected gore, biting infected animal), but the root cause of the plague would be less obvious, and thus a recurrence of the plague after the crisis had supposedly passed would be more likely.