I came up with a nice infection AU idea last year and am finally sharing it with you all because I might be able to make art for it this summer. 🚨⚠️ Warning! This may be a bit gory or just plain nasty for some audiences. >:P Viewer discretion is advised! ⚠️🚨

     Twilight would be an alicorn here and the two sisters would rule during this time. This would take place some time after season five. The season is spring.

     It began with a mare who was deathly ill required some extra assistance in recovering. This recovery had to remove whatever toxins remained in her stomach and blood because it wouldn't leave.

     Twilight Sparkle read somewhere that tapeworms could be used medically when they've been born in a sterile environment, almost like leeches. She came up with the idea of genetically modifying these tapeworms to speed up the healing process. Twilight Sparkle does not have a degree in the medical field. Keep this in mind for later on.

     She proposed these specimen eggs to the doctors of Ponyville. Twilight assured them over and over again that everything would be fine. She did her research and planned ahead just to make sure nothing could go wrong in this.

     The patient took a pill containing the tapeworm eggs when this plan was approved. She showed signs of getting healthier and this led to the Princess of Friendship receiving many praises for her work. After time went by, the patient took frequent visits to the hospital before being completely hospitalized once more. It was discovered that the mare became severely malnourished. When the mare consumed more, she lost the weight faster. The doctors considered removing the tapeworms altogether, but they seemed to have grown too powerful for any normal medicine to combat.

     Twilight, ashamed and constantly shunned, cooped herself up in her castle, blocking out all of the windows and never allowing any creature inside. Not even her very best friend and little brother, Spike. She couldn't stand to see the disappointment from her friends and family. So she stayed, only conducting infinite research on how to fix this and how to be a better pony. (Similar to how Luna tortured herself with nightmares.)

     The mare's condition only worsened with time. It was disclosed that she attacked the nurses who struggled to keep her contained. Those nurses were left dead and some severely injured. The patient escaped the hospital, her whereabouts unknown.

     That's how it all started. Some additional information about this outbreak:

     Is it contagious? Only through water supply and food supply. If someone is attacked by an infected, they cannot be infected because it does not transfer through bodily fluids.

     How? The tapeworms will know when the host is no longer useful or dying, so as a last attempt, the host will find a body of water for the tapeworms. The tapeworms would escape through the mouth and into the water body to lay eggs which contaminates the water. Any creature who ingests the water will be another host. There are rare cases (it's highly unlikely to happen) where someone encounters and infected that's dying. The infected will very forcefully expel the tapeworms and they'll burrow into the body of the victim.

     Who is immune? For now, non-equines. (Zebras and Ponies are equines.) If this mutates, other species may be at risk. Species that will never be at risk of getting infected are Dragons and Kirin because they have a naturally high body temperature of over one hundred degrees. (Hopefully they don't mutate to adapt to the heat.) 

     What truly made this like a zombie apocalypse? I know that zombie apocalypses seem highly unlikely, so I decided to go with something that was strikingly close and could happen without being too unrealistic. Real tapeworms would feed off of the energy (nutrients and anything eaten) that is in the host. This can make them heavily malnourished and even change their normal behavior. The patient was so starved, she acted on impulse and devoured anything in sight before she visited the doctor. It was never enough. Her appetite was never satisfied. (The tapeworms kept taking and taking from the host which is the definition of a parasite. They don't give back.) By the time she consulted a doctor, she was a little too far gone. The host at last attacked and ate the nurses and anypony else. (The tapeworms recognize which foods contain the highest nutrients that would satisfy them. Plants were not enough. Meat. Flesh. Blood. They contained the highest protein which would satiate them for longer.) To summarize, the fact that the hosts are driven not on thought, but on hunger is what makes them so zombie-like without them being dead.

     I'd like to add that at this point, the tapeworms can be considered a brain parasite as well since they manipulate the host. I would also say that just because someone was attacked doesn't mean that they will get infected. They can receive your normal infections like when a wound is not cleaned and protected properly. Characters can still contract regular illnesses.

     This was inspired by me seeing an image of tapeworms coming out of bears. One image is all it took to make all of this. I can show you, but I'll spoiler it twice so you don't accidentally click on the link if you don't want to see it. 

     Who's alive? The entirety of the Mane Six. Fluttershy is still in her cottage. She is at risk due to the stream around her house where she gets her water from. Twilight's status is unknown. Last seen in her castle. The rest of the Mane Six (Pinkie Pie, Rainbow Dash, and Rarity) is with Applejack and her family. They are disconnected from any other water system. They get their water from a well. Just to be safe, they boil the water and filter it. This is still early on in the infection.

     Extra details? The sad reality to this is that the host is still quite conscious. It is like they are a prisoner in their own body, unable to do anything about what's going on other than watch. They still have their normal pain tolerance meaning that they definitely feel any injuries. They just won't react to the immense pain they feel. The parasites within them keep the host moving, even when the body is falling apart. If you hear crying, they are not mimicking sound. They are actually crying. Do not approach. Hosts can make weak attempts to call for help. Do not help. I repeat, do not help.

     I'm not very sure what else I should add. Do you think I should make this contagious somehow through bites? Who else should be alive? Any other ideas to add onto this? Most importantly, what should this be called?

     Thank you so much for reading! I had so much fun writing this out and I hope to make this a reality.