There’s a whole study in a medical journal trying to figure out what disease Tiny Tim had in A Christmas Carol that

1. crippled him, but only in one leg;
2. would kill him over the course of a single year;
3. could be healed with 19th century medicine if a sufferer had access to enough money.

The smart money is apparently on either rickets or distal renal tubular acidosis, the treatment for both basically being oranges and beach vacations (two things a rich guy could provide).

Literaly in pokemon ruby, Wally is ill and moving to a town with fresh air cures him.