Korakthropy

Korakthropy is a rare mutation of the more common lycanthropy disease that afflicts only tengku.
Humans and mammalian humanoids infected with lycanthropy can turn into a predatory animal (often but not always a wolf) and an animal humanoid hybrid. Tengku with Karakthropy always transform into a raven or a very large humanoid raven with very sharp claws and a very deadly beak.
Like lycanthropy, karakthropy nearly always ends with the afflicted tengku developing a fondness for random murder. Karakthropes are very hard to put down because they fly. They can murder a bunch of people in one village and then fly fifty miles to another village or even further. Ravens are fast and stealthy birds.
Late stage karakthropes are not invincible and they can brought down with ordinary weapons, but they have very fast supernatural regeneration so a lot of damage needs to be inflicted in a short amount of time to kill them.
Wounds inflicted by silver weapons, heal much slower taking hours or even days to disappear making this the preferred weapon of choice.

Much like lycanthropes, the inherit magic of the moon does not force a transformation or a killing spree. But any lycanthrope or korkanthrope exposed to even a sliver of the full moon's light are exposed for what they are meaning they cannot hide in plain sight like they normally do. If the infected korakthrope has attracted organized armed resistance, most will choose to fly away to a remote location for the duration of the full moon rather than press the offensive (since their enemies will probably expect an attack on the full moon.
Lycanthropes often seek out their own kind and form small packs. Korakthropes are so rare that it is almost impossible for such a group to form, but they have been seen to work in pairs in rare instances. The idea of korakthrope mated pairs has chilling implications but has yet to be proven.

Transmission & Vectors

A tenkgu can be infected is possible (though not guaranteed) to be transferred to a humanoid through a bite from a lycanthrope, assuming the subject survives the bite. A tengku is even more likely to be infected if wounded by a karakthrope, even if the victim was only scratched and not pecked.
Korakthropy can also be passed from parent to child though there have only been two recorded instances of an infected tengku having offspring. In one case the offspring manifested symptoms of Korakthropy at adolescence, in the other instance the offspring was slain as an infant when her father's condition was discovered and a magical divination spell revealed the chick was a carrier.
Tengku are not known for having especially strong libidos. Most normal tengku children are conceived by both parents making a plan rather than the accidental product of a night of passion. It has been noticed that stage one and two Korakthropes seem to radiate pheromones or some sort of vibe that makes them especially attracted to the opposite sex.

Symptoms

Stage One: Initially, the infected tengku feels good, if not great. They have more energy and vitality though the tengku has a noticeable increased appetite. They recover from their lyncanthrope-inflicted injury quite quickly. Even their eyesight gets a bit sharper.
This period of increased energy can last for weeks or even months. Most tengku don't question anything is wrong because karakanthropy is so rare, most tengku haven't heard of it. They might question a human healer about lyncanthropy and either be told that lycanthropy only inflicts mammals not avians or they get explained the symptoms of stage one lycanthropy and then are relieved that they are not experiencing them.
Any increased vitality is usually rationalized as being a result of a brush with death leading to increased appreciation for life.

Stage Two: Headaches and dizziness. A lot of dreams about flying. Dreams about flying are common to even healthy tengku but these are especially vivid and intoxicating dreams. Increased irritability, sometimes accompanied by cravings for raw meat (note that tengku normally like their meat pretty rare to begin with).

Stage Three: The korakthrope starts transforming. Usually it takes a week or two at least for transformations to be fully controllable. Many tengku seek treatment at this stage, but many do not. Tengku with karakthropy can fly. That is something nearly all tengku secretly long for and it is hard to pass up even with the horrible strings attached.

Stage Four: The Korakthrope quickly develops bloodlust with a near constant urge to kill and eat things. Animals are okay in the short term, but mortal flesh is preferred and tengku flesh is preferred above all.
Frighteningly enough, karakanthropes typically have just enough restraint to lie low when organized hunters are seeking them out but not enough restraint to stop killing altogether. Lycanthropes on the other hand, typically do not have any restraint and will respond to hunters with automatic aggression.

Treatment

Rare herbs can be used to avoid the contagion of if the infected wound can be properly treated within a few days of the point of contact. The same medicines that treat early stage lycanthropy work on karakthropy (if someone thinks to use it, karakthropy is so rare many sages false believe that tengku are completely immune to the lycanthropy disease).
Beyond this, only powerful magic usually amplified by an epic quest can cure an afflicted lycanthrope.
Most people, tengku included, choose to "cure" late stage korakthrope with several silver arrows to the torso.

History

The first recorded case of karakthropy was in 1157 though it is likely to have existed in some form before that.  There are vague stories of humanoid raptor monsters in folklore long before that, though many storytellers and sages assumed that these monsters were spirits and not afflicted mortals.
Lycanthropy dates back all the way to the Second Unmaking.  It is unknown if karakthropy is a relatively new mutation of the disease or if lycanthropy always had the ability to infect tengku and it's just that no one noticed earlier.

Can karakthropes spread lycanthropy in mammalian humanoids?

Yes, but it is uncommon.
Humans and demihumans can only be infected with lycanthropy from an infected tengku's beak. The talons of a karakthrope can only infect tengku.
Since most karakthropes seek to down their prey with talons and then switch to their beak for the killing blow (or when the target is already dead), it is very unlikely that a human or demihuman will be pecked by a karakthrope and live long enough to develop lycanthropy.
Even then their odds of developing lycanthropy is far less than if they were bitten by an actual lyncanthrope.

Type

Supernatural

Parent

lycanthropy

Origin

Alien

Cycle

Chronic, Acquired & Congenital

Rarity

Extremely Rare

Affected Species

• tengku