You're saying that a forum, which is a place to have intelligent conversations about specific topics, is no place for proper spelling and grammar? What's more, there is any type of conversation anywhere where not sounding like a incoherent jabbering fool is acceptable? I have to disagree there.
What I am saying, is that perfect grammar shouldn't be expected on almost anything online, especially when it is a forum about a video game. It is not impossible for anyone to communicate an idea, or for somebody to correctly interpret that idea, without perfect grammar. I like these forums a lot, but I miss the times of Morrowind (please don't relate me to those people complaining about Skyrim not being Morrowind, that is not my point) when the forums were a happier place. Back when it was forums.elderscrolls.com... It seems like now, the forums have a very negative overtone where people are constantly taking stabs at each other. Ya I've made fun in this very thread, but I at least try to show that it is all in good fun. I've taken my college English courses already. When I am online, grammar is nowhere near as important as getting a point across.
I really like the ingredient recipes you can acquire throughout the game, but if I'm not mistaken, some mention items not listed in the ingredients menu, but under food instead. Also, I found a book about vampires that includes how to make a powerful poison, and how to make an invisibility potion with vampire dust.
As to the OP, what is wrong with crab chitin and charred skeever hide being mixed for all positive effects? I understand lots of rats are hosts to some diseases, but it's cooked to a char and then extracted to be used in a potion. Not 100% sure this is completely safe, but I would feel better with that than using raw rabbit leg.
EDIT: remembered that your main point is that they cure disease. Cant help ya there ha. Maybe the... uh.. antibodies of the disease are killed by the contents of that potion. (When it comes to how medicine works, I have absolutely no idea what I'm talking about haha)
EDIT(again): I just remembered, I don't think that book was about vampires, but about a town being attacked by bandits. Don't really remember.