Wereworm

A species of worm that parallels other types of tapeworms. This parasitic species is thought to be native to certain grasslands in the Trian Hinterland. Wereworm eggs can survive being ingested by herbivores and omnivores, including numerous types of livestock, in which they hatch and migrate as larvae into the creature's musculature where they protect themselves with shells called cysts. From there, wereworms can be transferred to a secondary carnivorous/omnivorous species that eats the first creature. In the final host, a wereworm leaves its cyst shell and secures itself along the digestive track where it consumes a percentage of animal proteins and biomass that the host ingests.   The wereworm has a 4 week (~20 day) ecdysis and reproduction cycle. During the 19th and 20th day of this cycle, the worm sheds its skin (along with much of an attached symbiote-infused nutrient storage layer) as well as an egg sac. The eggs and some of this symbiotic nutrient layer are excreted by the host (giving waste products a glow in the ultraviolet spectrum) but most of the nutrient layer is rapidly broken down and absorbed into the host's bloodstream. This impacts the host in two significant ways:

1. When the nutrients are processed by the host's cells, the attached symbiotic material splices together genetic information stored in the nutrient layer (i.e. genetics from the animals the host had previously eaten) with the host's own genetic code. If the host has, over time, eaten large quantities of a similar type of animal, the host's physiology will begin to change to have similar features of that animal (e.g. fur, hooves, claws, tails, etc).


2. The wereworm, now nutrient starved, will generate large amounts of biochemical signals to prompt the host to crave more animal protein foodstuffs. In many cases, the hunger cravings are so intense that they can send the host into a bloodthirsty frenzy where the host violently seeks out nearby prey.

 

Treatment

Firstly, the worm must be removed from the host to begin treatment. This is generally done via a selection of anti-parasite drugs or, if none are readily available, a lengthy diet regimen of only vegan foods (typically lasting at least 3 months but severe cases of well-developed wereworms have been known to take over a year to starve out).   Genetic damage as a result of the wereworms is more difficult to treat, can be costly, and requires access to state of the art medical centers with gene editing technology. The host's original genetic code needs to be retrieved (generally from redundant or vestigial organs which often seem to be the least affected by wereworm changes) and then rewritten to the rest of the body's cells.  

5e Rules

Disease: Were-blight
A creature that eats meat contaminated by wereworm larval cysts must make a DC 15 Constitution saving throw or become infected.   Seven weeks following infection, the creature will notice cosmetic changes to their body as they begin to gain subtle attributes of the animals they had eaten in the preceding weeks. The creature must also make a DC 15 Constitution or Wisdom saving throw to attempt to manage the cravings for fresh meat flooding their system from the worm. On a failure, the creature is single-mindedly focused on consuming meat (raw, cooked, fresh, rotten, whatever is available) and this state will not end until they have consumed at least 1 kilogram of meat or two days have elapsed, whichever occurs first. On a success, the creature is able to control their behavior but the cravings are still a distraction and as such, the creature gains 1 level of Exhaustion until two days have elapsed.   Every four weeks, this cycle occurs again with the cosmetic changes becoming progressively more pronounced and the DC to control the meat cravings increasing by 1 each time.