In the game, the disease spreads all over the Mushroom Kingdom and infects the Toads, causing them to grow large and round and rendering them mostly immobile. It is caused by Blorb Mushrooms that Fawful sold to several Toads, similar to how he sells the Vacuum Mushroom to Bowser. The entire case of the Blorbs is wiped out by the Miracle Cure, which is created after Mario and Luigi find and merge all three Star Cures.
Before the Miracle Cure eliminated the disease, Blorbed Toads block several areas in Toad Town. Once the disease is cured, these areas are opened up to the player. A large percent of the infected Toads, including the one seen in the cutscene at the beginning of the game, are kept in one of the rooms of Toadley Clinic.
- Although the Blorbs are cured after Mario and Luigi use the power of the Miracle Cure, there is, humorously, one Toad near the clinic that's still in a Blorb-like condition in Toad Town, saying that it is what he normally looks like.
- The way the Toads inflate after eating Blorb Mushrooms is similar to Violet Beauregarde's inflation in the book Charlie and the Chocolate Factory.