yeah, i did the stupid fucking tik tok thing

It's just something you catch; like a cold. It doesn't affect earth ponies instantly. And it hasn't affected Equestria at all, because it's quickly treated once symptoms show, because, like a cold, it'll just make you cough, give you a runny nose, etc. And ponies generally get their colds treated quickly, so they inadvertently treat the disease without even knowing.

Even then, it is quite rare, so normally you wouldn't even have to worry about it even when you do show symptoms. So, it's become forgotten in Equestria.

The disease does the following, depending on if you're a pegasi or a unicorn (or in the most rare of cases, an alicorn.):
- in the early stages, it'll start of as feeling like a cold, and during this stage, you basically do. It doesn't affect you more then that.
- if it's not treated in the early stages (3 or more days, *unless contracted to you by a separate pony.) ponies will become increasingly lethargic, it's still treatable, but ponies will likely have to be hospitalized for multiple days.

*the symptoms will seem less intense, and take longer to infect you then just 3 days. (Only if it's contracted to you through a pony suffering the early stages, if they're farther along in the stages, the disease has mutated much more by then, and you'll become infected much quicker than before)

- if a pony is still not treated by then, the disease makes your magic feel increasingly more painful to use, this includes flying for pegasi and alicorns. By now you've lost your inhibitions, and the disease will make it feel like the only way to relieve this pain is to expel it from your body. It's trying to weaken you, so you can then become its host organism, without fight.
        - ponies may achieve this by expelling bile, crushing or destroying their horn, and removing their wings by whatever means necessary.
- The disease will now spread itself to other ponies, whether that be through pony excrement, such as saliva, blood, bile, etc. Or by spreading through the air by creating spores on ponies bodies (rare cases, similar to ringworm.)
        - it knows ponies will eventually die, so it will escape to other magic ponies however it can.

Ponies who've developed into the later stages may become increasingly aggressive (cases vary), and will try to infect other ponies with their disease, due to the fact that the disease knows it's about to die inside of a pony. In these stages, the pony, mentally, is very aware of their happenings, but can do nothing to stop it, as their body no longer belongs to them.

During these later stages, earth ponies could get infected through any means that a unicorn, pegasus, or alicorn initially were wary to. Earth ponies have no magic to fight against it, so while it is slightly less contagious to them, and will not spread as quickly through their body, once it does earth pony bodies will have less of a chance to fight against it, and will die much quicker than magic ponies.

Once the brain dies, the body will die along with it (after a few days.) Once the body dies, it will infect the ground around them, and even grow contagious flowers, from the ground. it's important to dispose of these flowers instantly, as they could just as easily infect a pony. Be sure not to inhale it's fumes, or make direct contact with it with a bare hoof. Wear protection. If a flower is not removed properly, it will infest itself into the ground, and will spread uncontrollably until disposed of. Remove the plants COMPLETELY, stem and all, to prevent this.