D&D 5E Rules question

[mips42]

I'm going to get a chance to GM in my live game and I have a idea for a disease / infection but there arent really any guidelines for creating them in the DM's guide. Is it a "create what you want" or am I missing something?

 

[Lanliss]

I'm going to get a chance to GM in my live game and I have a idea for a disease / infection but there arent really any guidelines for creating them in the DM's guide. Is it a "create what you want" or am I missing something?

Do not think there are guidelines, but it seems simple enough to do. Make up an effect, attach a con save or two, and decide how long it lasts if it doesn't get cured.